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Gray, N., Carozzi, T.D., and Woan, G. (2012) Managing Research Data: Gravitational Waves. Project Report. University of Glasgow, Glasgow, UK.

Copyright © 2012 The Authors

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ManagingResearchDatainBigScience

NormanGray, TobiaCarozziandGrahamWoanSUPA SchoolofPhysicsandAstronomy, UniversityofGlasgow

2011July14, v1.1

Version v1.1

URL http://purl.org/nxg/projects/mrd-gw/report

Distribution Public

This reportwasprepared as part of theRDMP strandof the JISC programmeManagingResearchData.

Abstract

TheprojectwhichledtothisreportwasfundedbyJISC in2010–2011aspartofits‘ManagingResearchData’programme, toexaminethewayinwhichBigSciencedataismanaged, andproduceanyrecommendationswhichmaybeappropriate.

Bigsciencedataisdifferent: itcomesinlargevolumes, anditissharedandexploitedinwayswhichmaydifferfromotherdisciplines. Thisprojecthasex-ploredthesedifferencesusingasacase-studyGravitationalWavedatageneratedbytheLSC,andhasproducedrecommendationsintendedtobeusefulvariouslytoJISC,thefundingcouncil(STFC) andtheLSC community.

InSect. 1 wedefinewhatwemeanby‘bigscience’, describetheoveralldataculturethere, layingstressonhowitnecessarilyorcontingentlydiffersfromotherdisciplines.

InSect. 2 wediscussthebenefitsofaformaldata-preservationstrategy, andthecasesforopendataandforwell-preserveddatathatfollowfromthat. Thisleadstoourrecommendationsthat, inessence, fundersshouldadoptratherlight-touchprescriptionsregardingdatapreservationplanning: normaldatamanage-mentpractice, intheareasunderstudy, correspondstonotablygoodpracticeinmostotherareas, so that theonlychangewesuggest is tomake thisplan-ningmoreformal, whichmakesitmoreeasilyauditable, andmoreamenabletoconstructivecriticism.

InSect. 3 webrieflydiscusstheLIGO datamanagementplan, andpullto-getherwhateverinformationisavailableontheestimationofdigitalpreservationcosts.

Thereportisinformed, throughout, bytheOAIS referencemodelforanopenarchive. Someofthereport'sfindingsandconclusionsweresummarisedin [1].

Seethedocumenthistoryonpage 38.

Copyright2011–2012, UniversityofGlasgow

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http://www.jisc.ac.uk/whatwedo/programmes/mrd

School of Physics& Astronomy

Thisreportwaspreparedfor, andfundedby, theRDMP strandoftheJISC pro-gramme ManagingResearchData.

Release: 7b021525c2d7, 2012-07-1709:55+0100

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Contents

0 Introduction0.1 ProjectBackground p4

0.2 Howtoreadthisdocument p5

0.3 Workingwithcommunities –pragmatics p5

1 DatamanagementinBigScience1.1 LIGO inperspective: LIGO,bigscience, andastronomy p6

1.2 Datavolumes p6

1.3 Datamanagementstylesinthephysicalsciences p7

1.4 Astronomydata p8

1.4.1 StrasbourgDataCentre(CDS) asadisciplinaryrepository p11

1.4.2 Collaborationsinastronomy p12

1.5 HighEnergyPhysicsdata p13

1.6 Gravitationalwavephysics p14

1.6.1 Gravitationalwaveconsortia p14

1.6.2 GW data p15

1.6.3 Gravitationalwavedatareleases p16

1.6.4 Summary: big-sciencepreservationchallenges p16

1.7 A contrast: socialsciencedata p17

1.8 Babyloniandatamanagement(lesscontrastthanyou'dthink) p18

1.9 Bibliographicrepositories p19

1.10 VirtualObservatories p19

1.11 Dataproductsandproprietaryperiods: reifyingdatamanagementandrelease p20

2 Theresponsibilitiesfordatapreservation2.1 Visualisingbenefits p21

2.2 Thecaseforopendata p22

2.3 Thecasefordatapreservation p24

2.4 Shouldrawdatabepreserved? p25

2.5 OAIS:suitabilityandmotivation p25

2.6 Whatshouldbig-sciencefundersrequire, orprovide? p26

3 Thepracticalitiesofdatapreservation3.1 Modellingthearchive p27

3.1.1 TheOAIS model p27

3.1.2 TheDCC CurationLifecyclemodel p28

3.2 Softwarepreservation p29

3.3 Datamanagementplanning p30

3.3.1 DMP inspace p30

3.3.2 CurrentandfutureDMP intheLSC p30

3.4 Datapreservationcosts p31

3.5 TheGW communityandtheAIDA toolkit p33

4 Conclusionsandrecommendations

A Casestudy

B AIDA assessment

Aboutthisdocument

References

Glossaryandindex

3

Gray, CarozziandWoan

0 Introduction

Astronomyisasoldashumanculture. Earlyagriculturalcivilisationsrequiredreliablepredictionsof thepositionsandmotionsof theSunandMoon, inor-dertopredict inturnseasons, tides, andriverrisings. Evenintheabsenceofanextensivescientificmodel, thesepredictionsreliedoncarefulobservations,preservedintheformofalmanacsorephemerides. Documentssuchastheseassociateastronomywithnotonlythefirstdataarchivesbut, sincetheseartifactsstillexist, alsotheoldestdataarchivesintheworld. Long-termdigitalpreserva-tioninastronomyisnothingnew. Wecannotresistsayingmoreaboutthis, inSect. 1.8.

Astronomicalarchivingdoeshoweverevolve, andinthelastfewdecadesbothastronomyandparticlephysicshavehadtobecomeleadersinlarge-scaledatamanagement.

Althoughastronomicalimages(nowallborndigital)havealwaysbeensub-stantialinsize, theyhavegenerallybeenreasonablymanageable. Newerastro-nomicaltechniques –andwearethinkingof21stcenturyradioastronomyandgravitationalastronomy –arecapableofgeneratingtrulychallengingquantitiesofdata; andparticlephysicshasbeengenerating, andaddressing, intimidatingdataproblems fordecades. Theseproblemscoverboth themanagementandpreservationoflargedatavolumes, astechnicalproblems, andthepreservationofthedata'sinformationcontent, onsubstantiallyvaryingtimescales.

0.1 ProjectBackground

TheManagingResearchData/GravitationalWavesproject (MRD-GW) iscon-cernedwiththedatamanagementarrangementsofthe LIGO ScientificCollabo-ration(LSC),andofthebroader GravitationalWave(GW) community. ItisoneofthesixprojectsintheRDMP strandoftheJISC ManagingResearchData(MRD)programme [2].

TheGW communitywasselectedbythe ScienceandTechnologyFacilitiesCouncil(STFC),atJISC'sinvitation, asarepresentativeexampleofbig-sciencedatamanagementpractice –asweelaboratebelow, ithasfeaturesofboththetraditionalastronomyandHEP communities, withoutbeingidentifiablewithei-therofthem. Whilemanyofthespecifics, below, relatetothiscommunity, webelievemuchofthediscussionisrelevanttotheotherdisciplines. Here, wearefocusingonthebig-scienceprojectswhichreceivestrategicsupportfrom STFC,ratherthanthesmaller-scaleprojectsfundedbyspecificresearchgrants, sinceitistheselarge-scaleprojectsthataredistinctiveaboutSTFC-fundedresearch.Weassumethattheoutputsofthesmallerprojectswillbemanagedthroughdis-ciplinaryrepositories, inamannerwhichmorecloselyresemblesthatofotherresearchcouncils.

TheMRD-GW projectexiststoinformthreesetsofstakeholders:

• Although the Joint Information SystemsCommittee (JISC) and the DigitalCurationCentre(DCC) haveextensiveexperiencewithdigitallibrariesanddigitalcurationingeneral, thereareproblemsspecificto‘bigscience’datawhichJISC wouldliketobetterunderstand.

• TheResearchCouncilshaverecentlystartedtorequirebidderstoincludea‘datamanagementplan’withinprojectproposals. HoweverthereisnoconsensusonwhatsuchaplanshouldlooklikeforsciencefundedbytheSTFC.TheUS NationalScienceFoundation(NSF) hasrecentlyplacedbind-ingrequirementsonprojectstoproducedatamanagementplans [3].

• TheLSC communityhasconsiderableinternalsoftwareandadministrationexperience, andhassolvedalargenumberofdatamanagementproblems

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focused on large-scale data storage and transport. However there is anawarenessthat(partlybecausetherehavebeennoimmediateimperativestodoso) therewasuntil recentlynopublishedplanfora long-termdataarchive.

Theexistenceof these threegroups is reflected in theoverall structureof thedocument.

Thisproject'scontextalsoincludesthebroad VirtualObservatory(VO)move-ment, whichaimstodevelopstandardsandareasofconsensuswhichhelpsci-entistshavereadyaccesstoastronomicaldataacrosssub-disciplinesandwave-lengths. Allthestakeholdergroupshaveinterestsinthesuccessofthe VO move-ment.

Theprojectaims tobring together twosetsofpractice, namely the long-termdigitalpreservationperspectivesrepresentedbytheOAIS referencemodelintheabstractandthe DCC inparticular, andtheveryconsiderableexperienceofpracticallarge-scaledatamanagement, embeddedwithintheLSC community.

0.2 Howtoreadthisdocument

Thisdocumentisorganisedintothreemainsections, broadlycorrespondingtothethreeaudiencesweareaddressing.

Sect. 1 isaboutdatamanagementin bigscience. Itisaddressedtothe JISCandtothedatapreservationcommunityingeneral, andisintendedtoilluminatetheways inwhich scientists in theseareashavedistinctivedatamanagementrequirements, andadistinctivedataculture, whichcontrastsinformativelywithotherdisciplines.

Sect. 2 isprimarilyaddressedto STFC andothersimilarfundersofthistypeofscience. Itisconcernedwiththeresponsibilitieswhichareimposedonfundersbythewidersociety, andwhicharepassedontothefundedthroughrequirementsonthegovernanceofprojectsandtheavailabilityofdata. Therecommendationshereareconcernedwithhowbesttoexpresstheseresponsibilities.

Finally, Sect. 3 isprimarilyaddressedtothe LSC,asaproxyforsimilarbig-scienceprojects. Theexplicitrecommendationshereareintendedtobeofasmuch interest toprojects, asactions theymaywish to take, as to funders, asbehaviouritmaybeprudentorproductivetorequire.

0.3 Workingwithcommunities –pragmatics

Thisreportistheresultofafruitfulcollaborationwiththe GW community. Itmaybeusefultonotesomeofthefeaturesoftheproject, andthecommunity, whichcontributedtothis.

• Theprojectteam, aspartofGlasgowUniversity, hascurrentinvolvementinthecommunity, andtheprojectdirector(Woan)isaseniorfigurethere.

• The LIGO communityisalreadyawareofthegeneralneedfordatamanage-ment, andthespecificneedforpreservation(see [5]).

• Theprojectpersonnelhaverelevantscientificbackground, andaretosomeextentinthepositionofbeinginformatics-for-astronomyspecialists(iewe're‘insiders’).

• Thecommunityislargeand(viastudiessuchas [6])hassomeexperienceofbeing‘studied’.

• Theexisting LVC workshopseriesmeantthatwecouldcontactrelevantpeo-pleeasilyinacontextwherenewcomerswereexpected, andwedidn'thavetoaddourowndatamanagementworkshop.

ForOAIS,see [4]andSect. 3.1.1; inthisreportthe‘DCC’istheJISCDigitalCurationCentre, nottheLIGO DocumentControlCenter.

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http://askanexpert.web.cern.ch/AskAnExpert/en/Accelerators/

LHCgeneral-en.html

Inthecontextoflarger-scaleprojects, a‘sciencerun’isaperiod

whentheequipmentisrunmore-or-lesscontinuously, gatheringscientificallyusefuldata. Betweenscienceruns, theexperimentwill

eitherbedownformaintenance, oronaplanned‘engineeringrun’; datafromengineeringrunsisgenerallystored, butisnotexpectedtobe

usefultoscientists.

ATLAS,oneofthetwolargerLHCdetectors, stores 3 PB yr−1 byitself;see http://atlas.ch/pdf/atlas_

factsheet_4.pdf forsomeentertainingnumbers.

1 DatamanagementinBigScience

1.1 LIGO inperspective: LIGO,bigscience, andastronomy

Whatis‘bigscience’?Big scienceprojects tend to sharemany featureswhichdistinguish them

fromthewaythatexperimentalsciencehasworkedinthepast. Suchprojectsshare(non-independent)featuressuchas:

bigdiscoveries Theseprojectsareexpectedtobeamongstthemostimportantonesoftheirgeneration. Althoughthereisveryhighconfidencethattheirheadlinesciencegoals(forexampletheHiggsandGW searches)willbesuc-cessful, theyarealsoexpectedtoproducelonglistsofunexpectedresults,andabroadrangeofengineeringspinoffs.

bigmoney Thesearedecades-longprojects, supportedbycountry-scalefundersandbillion-Eurobudgets(thetotalbudgetforthe LHC isaroundthreebillionEuros, not including thedetectors, nor thepersonnelandhardwarecostsdirectly supportedbycountry funders, whichcostbetweenoneand twotimesthatsum).

bigauthorlists Theprojectsinvolvecollaborationsofhundredsofpeople(theLSC authorlistrunsataround600people(cf Sect. 1.6.1), andtheLHC'sATLAS detectorauthorlistisaround3000).

bigdata Enhanced- andAdvanced-LIGO (for example)will produceof order1 PB yr−1, comparabletothe ATLAS detector's 10 PB yr−1; theeventualSKAdatavolumeswilldwarfthese.

bigadmin MOUs, councils, workshopseries.

bigcareers Individualsmaymake the journey fromPhD tochairona singleproject.

Thereisadiscussionofthefeaturesof‘bigscience’, and LIGO'sprogresstowardsthatstyleofworking, in [7], withanextendedhistoryofthesub-disciplinein [6].

Becauseofthelargecostsinvolvedandbecausethereisusuallylittleimme-diatecommercialvalueinthisresearch(thoughofcoursetherearesubstantiallong-termeconomicpayoffsfortheinvestingcountries), theselargeprojectsarefundedatthenationalorinternationallevel, sothattaxpayersaretheultimatestakeholders. Evenputtingasidethescientificandscholarlyneedforadequatedatapreservation, thesenationalinvestmentsmakeitnecessaryforfundersbothtodemonstratethatprojectsarebeingefficientlyexploitedtoproducemacro-economicvalue, andtomakethe dataproductsavailableforpublicuse. WediscussopendatainSect. 2.2

1.2 Datavolumes

Themostimmediateproblemwithdatacurationandsharinginthesescientificareas –thoughintheendnotthemostsignificantone –isthedatavolumesin-volved. ThecurrentvolumeofLIGO dataisoftheorderofhundredsofterabytes,andthedataratesisexpectedtogrow, overthecourseoftheproject, fromitscurrent 100 TB yr−1 toaround 1 PB yr−1 (seeTable 1 onthefacingpage, whichshowsthevariationindatasizeforsciencerunsthreetosix).

LIGO isjustoneofseveralotherexistingorplannedbigphysicsprojects, in-cludingthe LHC,the SquareKilometreArray(SKA),andvarious EuropeanSpaceAgency(ESA)/NASA spacemissions. Incomparisonwiththeseprojects, LIGO'sdatahandlingrequirementsarerelativelymodest. TheLHC willhavedatavol-umesoftensof PB yr−1 Furtherinthefuture, theSKA (whichisduetobecom-

6

http://askanexpert.web.cern.ch/AskAnExpert/en/Accelerators/LHCgeneral-en.html



http://atlas.ch/pdf/atlas_factsheet_4.pdf

http://atlas.ch/pdf/atlas_factsheet_4.pdf


S3 S4 S5 S6L0 57 32 816 261L1 8.24 4.04 119 76L2 1.55L3 0.97 0.86 9.70 3

(duration/day) 70 29 695 482

Table 1: LIGO datasetsizeestimatesinTB,andrunlengthsindays, forsciencerunsthreetosix(‘Sn’), andvariousdatatypes(sizedatatakenfrom [8]; therewereatotalofsixsciencerunsinLIGO;L0istherun'srawdataset, andL1toL3areprogressivelyreduced).

missionedaround2020)haspredictedrequirementsupto 1 Tbit s−1 locallyand100Gbit s−1 intercontinentally; thisinvolvestransporting, thoughnotnecessar-ilystoring, around 1 TBmin−1 or 0.5 EB yr−1 [9]. Thisis0.05%ofthepredicted1ZB yr−1 total worldwideIP trafficfor2015 [10].

Large-scale physical science experiments have long produced significantdatavolumes, but in recentyearsdatasetsappear tobe increasing involumeandincomplexityatanoverwhelmingrate, andthismaypresentaqualitativelydifferentdatamanagementproblem. Thisissometimesdescribedinratherapoc-alypticterms –asa‘datadeluge’orthelike –andsomeofthechallengesandopportunitiesaredescribedin [11].

1.3 Datamanagementstylesinthephysicalsciences

Itseemsusefultodiscuss, here, someofthedistinctivefeaturesofdatacollec-tionandmanagementintheexperimentalphysicalsciences, sincethesehaveanimpactonboththeexpectationsfor, andtheproblemswith, thedata.

Big-scienceresearchprojectshaveanumberofrelevantcommonfeatures:

Largedatasets Suchprojects'datasetsare‘large’intheobjectivesensethattheprojectsaretypicallysogreedyfordatastorage, thattheirholdingsareneartheedgeofwhatitistechnicallyfeasibletostoreandtransport.

Innovativedatamanagement Aspartoftheresponsetotheirneedforlargedatavolumes, big-scienceprojects are often extremely innovative in their so-lutions todatamanagementproblems, to theextent that theyarewillingtoworkwithexperimentalfilesystemtypes, oradaptandextendoperatingsystemsoftwareornetworktransportprotocols(see http://lcg.web.cern.ch/togetanimpressionofthescopeofdevelopmenteffortshere).

Specialisedsoftware Becausetheinstrumentsandtheirdatasetsaresocompli-cated, theseprojectstypicallygeneratelargecustomdataanalysissoftwaresuites. Thesemayrequirespecialisedandunwrittenknowledgetouse, andthereforeappeartorepresentasignificantsoftwarepreservationchallenge.

Beyond the substantial softwareengineeringchallengesdescribedabove,thephysical sciences tend to have few ‘IT’ problems, since the communitiescontainplentyofpeoplewithsufficienttechnologicalnoustoaddressessentiallyallday-to-daycomputing-relatedproblems, andthesecommunitiesarethereforegenerallyreasonablywell-organisedwithregardtobackups, storage, andbasicfilesharing(seealsothediscussionoftechnologicalreadinessinSect. 3.5). Atthesametime, however, thecommunitiesareratherconservativefromthepointofviewofacomputerscientist, andsometimesratherinformalfromthepointofviewofasoftwareengineer. Thatis, theattitudetocustomcomputingsolutionsisverysimilartotheattitudetocustomlabhardware: itmayneedtobecreative

1 PB is 1000 TB; 1 EB is 1000 PB;1 ZB is 1000 EB; notethattheunit Breferstobytes, notbits

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http://lcg.web.cern.ch/


OneoftheDCC researchers,commentingonthisreport, quoteda

GridPP surveyrespondentcommentingthattheLHC

computingtask: “Providingresilientservicesthatmaintainaccesstodata

fortheexperimentusers24/7 –servicesarecomplex, bleedingedge,

andareconstantlybeingupdated.Controllingthatprocess, whilstalsomaintainingserviceup-timeisvery

challenging”.

andexperimental, butnever for its own sake; itmustbe stable, but is neverfrozen; itisaccuratelymade, butrarelypolished. Theanalogywithlabhardwareandsoftwareholdstotheextentthat, intheLHC community, datamanagementgroupsareregardedasdetectorsubsystemgroups; thatis, theyhavethesamegeneralstatusasthemagnetoracceleratorengineers, andexpectedtoproduceagileandinnovativecomputingservicesverydifferent fromthemoreroutine,lab-wide, provisionofCERN IT services.

Theresultofthisisthatlabsoftwarerepresentsfunctionalsolutionstoim-mediate-termproblems, generallywithflexibilityenoughtorespondtomedium-termproblems, butwithoutmuchattentionbeinggiventotheimponderablesofthe long term, after theexperimenthascompleted. It isprecisely these LongTermpreservationquestions, in theOAIS senseofmore thanone technologygeneration, thataretheconcernofthisreport.

There is plentyof prior art in this area. See reference [12] for a reviewofdatamanagementpracticeinavarietyofscholarlyareas, whichadditionallycoversseveralproposedlife-cyclemodels, andanalysistechniques. ThereisasimilaroverviewinthePARSE.Insightcase-studiesreport [13], whichexaminesdatamanagementpractice inHEP, earthobservation, and social scienceandhumanities. Thesecase-studieswereconductedviainterviews, andparticipationinongoingeffortswithinthecommunities. Thesameprojectproducedagapanalysisandroadmap, whichmakevaluablereading.

This isagoodplacetostress that ‘bigscience’generallyhandles itsdatawell, andcanevenberegardedasexemplary(compareSect. 3.5). Thereareafewfeatureswhichnaturallyencouragegooddatamanagementpracticeinthelarge-scalephysicalsciences.

• Theseareoftenrelativelywell-resourcedprojects, withplentyofcomputingexperienceandlotsofengineeringmanagement. Thereislotsofobviousin-frastructureinthedevelopmentofalargecollaborativeexperiment, whichgivesdatamanagementanobviousbudgetaryhome, whereitisnotcom-petingwithfundingwhichdirectlysupportsresearchers.

• AstronomyandHEP projectshavealwaysproduced‘large’datavolumes:thismakes adhoc datamanagementmanifestlyunattractive, andencour-agesexplicitdatamanagementplanninganddiscipline.

• Thescaleoftheseexperimentsmeansthattheytendtobesharedfacilitiesprovidingdocumentedservicestotheirusers, sothatdocumentedinterfacesandSLAsarenatural.

• Theseprojectsrarelyifeverproducecommerciallysensitivedata, sothattheconfidentiality concerns arewell circumscribed, concerningprofessionalpriorityratherthanIPR orotherfinancialworries.

Althoughthesefeaturesaretoagreaterorlesserextentspecifictothistypeofscience, theyhavegivenrisetothenotionsof dataproducts andexplicit propri-etaryperiods, whichwebelievewouldbeusefulinotherareas, andwhichwediscussinSect. 1.11.

Althoughitis GW datawhichisournominalfocusinthisreport, itiscon-venienttofirstdescribegeneralastronomydata, thendistinguishthatfrom HighEnergyPhysics(HEP) data, whichhasasomewhatdifferentdataculture, andthendescribehowtheGW community, whichisinmanywaysintermediatebetweenthetwo, handlesitsdata.

1.4 Astronomydata

Astronomy(excludingGW astronomyfor themoment)hasprobablythemoststraightforwarddatamanagementpracticesinthephysicalsciences. Whenan

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opticaltelescopetakesanimage(oraspectrum, whichforourpresentpurposesistechnicallyequivalenttoanimage), eitheraspartofasystematicsurveyofthewholeskyorasapointedobservationrequestedbyanastronomer, theimageis typicallymoved fromthe telescope'sdetectorstraight into itsarchive, fromwhereitcanbelaterretrievedbytheastronomer, accompaniedbyautomaticormanually-addedmetadata.

Non-opticalastronomers(coveringtherestofthespectrum, fromradiotogammarays), andmostsatellitemissions, haveasomewhatmorecomplicatedroutefromobservationtoimage, andabroadersetofdataproducts, buthaveessentially thesamemodel, andthesamedisciplineandexpectationsaroundarchives. Fromthepointofviewofdatamanagementtherefore, wecanelidethedifferencesbetweenthevariousbranchesofastronomy. Gravitationalwaveandneutrinoastronomy, incontrast, arenotstudyingtheelectromagneticspectrum,andpartlyasaconsequencetheirstudymorecloselyresemblesparticlephysics(seeSects. 1.5 and 1.6 below).

Most large telescopes, satellites and instruments operate partly or exclu-sivelyaccordingtoamodelinwhichastronomersareawarded‘telescopetime’,rangingfromafewhourstoafewnights, astheresultsofcompetitivebidscloselyanalogoustograntbids. Theresultingdatagenerallyhasaproprietaryperiod,extendingforperhaps12, 18or24monthsafterthedataistaken, duringwhichonlytheobserverwhorequesteditcanretrieveit, butafterwhichitautomati-callybecomesretrievablebyanyone(‘embargo’wouldbeabetterterm, thoughunconventional). Similarly, instrumentsbuiltbyconsortiagenerallyhavepro-prietaryperiodsduringwhichthedataisonlyavailabletoconsortiummembers.Theproprietaryperiodsarepartlyforthebenefitoftheconsortiumindividuals –itistheirrewardfortheinitiativeandpossiblydecadaleffortofbuildingtheinstru-ment –buttheyarealsoapragmaticreflectionofthelengthoftimeitmaytaketocalibrateandvalidateacquireddata, readyfordepositinanopenarchive. Asaresult, thelengthsandtermsofproprietaryperiodsarethesubjectofnegotiationsbetweentheinstrumentbuildersandtheirultimatefunders, thoughthenegotia-tionsarealwaysaboutthelengthofthedelaybeforeageneraldatarelease, andneverquestionthenecessityforthereleaseitself.

NASA missionsnowtypicallyhave12-monthproprietaryperiods, butthishasvariedhistorically, andforexamplethe1990COBE mission, whichincludedsignificanttechnologicalnovelty, andwhoseperformancewasthereforeratherunpredictable, hada36-monthproprietaryperiod.

Notallinstrumentshaveformalreleaseplans, andtheproprietaryperiodsthatexistmaybeadjusted informally. Caltech isoneof the fewprivate insti-tutionswhichisrichenoughtoown, orhaveasignificantsharein, world-classtelescopes(PalomarandKeck). Ithasnodeclaredpolicyondatamanagementordatasharing, beyondabroadtacitexpectationthatdatawillbepublishedasap-propriatefornormalscientificpractice. Asasecondexample, duringthe‘sciencedemonstrationphase’ofthecommissioningoftheHerschel telescope(thatis, thelastcommissioningphase, verifyingthatthesciencegoalswereachievable), theinstrumentteaminvited observerstonominatepartoftheirscheduledobserva-tionstobeperformedearly, duringthisstill-experimentalcommissioningphase.Whentheobservationsprovedsuccessful(astheygenerallywere), theobserv-ingteamsweregiventhechoiceeitherofmakingthedataimmediatelypublic,intimefortheopeningoftheHerschelarchiveandajournalspecialissue, andhavingtheobservationtimere-creditedtothem; orelseretainingthe12monthproprietaryperiod withoutthere-credit.

Imagedataisthearchetypalastronomydata, andisgenerallystoredasfiles,butanotherimportantcategoryistheastronomical‘catalogue’, ofobjectposi-tions, spectraandotherproperties, usuallystoredinrelationaldatabases. Astro-nomicalarchivesrangefromquitesmallones(atoneextreme, asmallspecialisedinstrumentmayhaveits‘archive’consistingofafileserverlookedafterbyagrad-

An‘instrument’inthiscontextisthelight-sensitivedetectorattachedtothetelescopeorsatelliteoptics(thecamera, ineffect). Itisreplaceableorswappable, andregardedasaseparatepieceofengineeringfromthetelescope. Thedayswhenobserverswouldtraveltothetelescopecarryingtheirowninstrumentarenowlargelypast.

See‘HerschelObservers'Manual’§1.1.4, http://herschel.esac.esa.int/Docs/Herschel/html/ch01.html;thankstoHaleyGomezforbringingthistoourattention.

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http://herschel.esac.esa.int/Docs/Herschel/html/ch01.html

http://herschel.esac.esa.int/Docs/Herschel/html/ch01.html


http://surveys.roe.ac.uk/ssa/

uatestudent)toverylargeprofessionallymanagedarchiveswhichareboththeprimarysourcesofsomedatasets, andmirrorsofothers.

Astronomydata ispotentiallyvery long-lived. Althoughastronomersarenaturallydrawntothenewestinstrumentswiththegreatestsensitivity, itisnotunusualtodrawonrelativelyoldarchivedata. Inmostcases, thiswillbestillbeborn-digitaldata, butdigitisedversionsof century-oldastronomicalplatesareusedinpreciseastrometry, andtoidentifytheprecursorsofsupernovaeandotherone-offevents(seeforexampletheEdinburghSSA,furtherdiscussed, withbackground, at [14]; andamorediscursiveaccountofplatescanning, includ-ingdiscussionofsomeofthearchivalchallenges, in [15, 16]). Evenbabylonianandancientchineseastronomicaldata hasbeenusedforcontemporaryscience,helpingmeasuretherateatwhichtheearth'sspinrate, andthusthelengthofday, ischanging [17]; similarly, 3 000-year-oldegyptiandatahasbeenusedtomeasurethechangeintheorbitalbehaviourofthethreestarsintheAlgolsys-tem [18]. Thecosmoschangesslowlyonourtimescales, sothatthegreatmajor-ityofastronomicalobservationsarerepeatable; theexceptionsarethosecaseswherelongtime-basesarenecessary(preciseastrometry)orwheretheobjectofstudyisaone-off, andthereforeunrepeatable, eventsuchasarecentorhistoricalsupernova.

Astronomydataisalsointelligibleinthelongterm: althoughuntranscribedbabyloniantabletscanonlybereadbyspecialists, contemporaryastronomerscanbasicallyunderstandthedatapublishedinKepler's1627 RudolphineTables,andwithsomeassistancecanunderstandthecontentofthe11th-to12th-centuryToledanTables [19]. Althoughbiologistsmightbeabletomakesimilarclaimswithrespectto, forexample, Linnæus'sobservations, itishardtofindequallylong-liveddatainthephysicalsciences, orborn-analoguephysicsdatawherethereisasimilarcontemporarypressurefordigitisation.

Thereisessentiallynofile-formatproblemin(electromagnetic)astronomy,since the Flexible ImageTransport System (FITS) format isuniversal [20, 21].Thoughnotperfect, thisisarelativelysimpleandwell-definedformat, combiningbinaryortabledatawithkeyword-valuemetadata.

Astronomicaldataalsohasawell-developednotionof dataproducts. Thesearedatasetswhichcontain, not rawdata, butdatawhichhasbeenprocessedtoa greateror lesser extent. Wecandistinguish at least three levelsof data inthiscontext; most large instrumentswillhavemore thanone levelofderivedproducts.

Rawdata Thisisthelowest-leveldata, consistingofthedirectoutputofade-tectororotherinstrument, ortherawsatellitetelemetry. Thisdataismademeaningfulonlybyprocessingwithsoftwarewhichistosomeextentspe-cifictotheequipmentinquestion. Thoughitwillbepreservedasamatterofcourse, itisrarelypublished, norusedby, norusefulto, otherresearchers,exceptinunusualcircumstances. Inthecaseofaparticularlysubtleeffect –orlesscommonly, adebateoveratheoreticalanalysisorcalibration –are-searchermightreturntothe rawdata, butthiswillgenerallybedonewiththecollaborationoftheinstrumentscientists, andmaybeotherwiseinfeasi-ble, totheextentthatanyresultsobtainedwithoutsuchinsiderknowledgemightnotbebelievablebythebroadercommunity.

Dataproducts Afteritisgathered, (raw)datamustbeprocessed(‘reduced’)toturn it intoscientificallymeaningfulnumbers (interpretingengineeringortelemetrydatastreams, andcalibration)andtoremovevariousinstrumentalandobservationalartefacts. Dataproductsareusuallymadeavailable instandardformats(inastronomy, generallyFITS files), whereasrawdata, ifitismadeavailableatall, maywellbeinaninstrument-specificform.

Publications Sittingabovethedataproductsisaclassofhigh-leveloutputs, in-

10

http://surveys.roe.ac.uk/ssa/


cludingscientificpapers, andotherpeer-reviewedoutputssuchaspublishedcatalogues. Journalarticlesarecuratedatpublishersitesandthe Astrophysi-calDataService(ADS),andarticlepreprintsatthe arXiv(cfSect. 1.9). Mod-estvolumesofdatacanbepublishedasdigitalappendicestojournalarti-clesin, forexample, AstronomyandAstrophysicsSupplements; thesearecuratedatthejournalandat VizieR.

Itisthedataproducts whicharetheoutputswhicharesufficientlyfreefromobservationalartefactstobethestartingpointforscientificanalysis(high-levelproductsaresometimesreferredto, informally, as‘sciencedata’), andwhichrep-resenttheclassofdatawhichisnaturallyarchived, mostcarefullydocumented,andwhichwilleventuallybemadepublic. Theremaybemultiplelevelsofdataproducts, withlower-levelproductscarryingmoreinformation, butusingwhichrequiresmoredetailedknowledgeofthesubtletiesoftheinstrumentanditspro-cessing pipeline. ToamuchgreaterextentthanistrueforHEP data, forexample,thehighestlevelastronomydataproductsarebothusefulandgenerallyintelli-gible –everyoneis, afterall, lookingatthesamesky –butresearcherswilloftenuseintermediate-levelproducts, iftheycaninvestthetimetolearnaboutthem,orhavecollaboratorswhohaveexperiencewiththem. Thoseresearcherswhoaremoreintimatelyinvolvedwithaninstrumentwillbecomfortableusinglower-leveldataproducts, becausetheywillhavetheknowledgewhichenablesthemtorun, orexperimentallyre-run, thepipelinesinascientificallymeaningfulway.Thatsaid, inOAIS terms, astronomicaldatacanbecharacterisedashavingabroad DesignatedCommunityandwellunderstood RepresentationInformation.

Publicationsareintheprovinceoflibrariesandsimilarrepositories, andarenotconsideredfurtherinthisreport.

Opticalastronomy(thatis, withobservationsmadeusingvisiblelight)hasthemoststraightforwarddata, sothatthedistinctionbetween rawdataanddataproductsisslighttothepointofbeingratherartificial: astronomersreusingopti-caldatawouldexpecttorecalibratetherawornearlyrawdata, andwouldnotanticipatehavingdifficultydoingso.

Weconcludewithsomeexamples: A typicaltelescopearchiveistheUKIRTarchiveat http://archive.ast.cam.ac.uk/ukirt_arch/; thereareseveralimageandspectrumarchivesattheRoyalObservatoryEdinburgh'sWideFieldArchiveUnit;andthereisalargecollectionof cataloguesavailableat StrasbourgDataCentre(CDS) (seeSect. 1.4.1 below).

The ESA Hipparcosastrometrymission flewbetween1989and1993, andproduced ahigh-precision catalogueof 100 000 stars [22]. The catalogue isavailableonlineasqueriabledatabasesatESA and CDS,asCDs, andasPDFswhichmatchthecatalogue's17-volumeprintedversion. Theprintedversionisaninterestingcase: asdiscussedinthecatalogue(vol. 1, §2.11.3), theprintedpagesaredesignedwithaper-pagechecksum, tohelpwithre-scanningthecat-alogue frompaper, in thepresumed-likely futurecase that thedigital versionbecomesunreadableandonlycopiesofthepaperbooksurvive. TheTychocat-alogue, fromthesamemission, comprisesaround20timesthenumberofstars,atlowerprecision, andisonlyavailableonline.

ThereissomediscussionofpreservationcostsinSect. 3.4.

1.4.1 StrasbourgDataCentre(CDS) asadisciplinaryrepository

CDS isalargedisciplinaryrepositoryforastronomy [23]. Itstoresabroadrangeofcatalogues, ofvarioussizes, inits VizieR service(see[24]and http://vizier.u-strasbg.fr/) and provides a large librarian-curated collection of data from,measurementsof, andreferencesto, individualastronomicalobjects. Itcoop-eratescloselywith ADS.

CDSwascreated, andissupported, bythefrenchagencyinchargeofground-basedastronomy –firstCNRS/INAG thenCNRS/INSU –asajointventurewith

http://www.roe.ac.uk/ifa/wfau/

http://www.esa.int/science/hipparcos

http://www.rssd.esa.int/index.php?project=HIPPARCOS

11

http://archive.ast.cam.ac.uk/ukirt_arch/

http://vizier.u-strasbg.fr/

http://vizier.u-strasbg.fr/







WearemostgratefultoFrançoiseGenova, ofCDS,forthisdiscussion

ofCDS'shistoryandsupport.

http://www.nottingham.ac.uk/astronomy/UDS/,

http://www.h-atlas.org/,http://hermes.sussex.ac.uk/,http://www.gama-survey.org/

StrasbourgUniversity. Themainsupport is throughpermanentpositions fromtheCNRS/INSU andtheUniversity(researchers, computerengineers, andspe-cialisedlibrarians), withadditionalcontractssupportedbyfundingfromvarioussources.

CDS isadministrativelylocatedwithinaresearchstructure, StrasbourgOb-servatory, providinganactiveresearchenvironmentforCDS astronomers. Thepreservationaspectshaveneverbeenseparatedfromtheprovisionofservicesandthemaintenanceoflocalexpertiseondatamanagementandpreservation.

Thiscanbeseenasanexampleofaverysuccessfuldisciplinaryrepository.Thereappeartobeseveralkeyfeaturesofthissuccess.

• CDS hasestablished, andactivelymaintains, internationalleadershipinthecurationofastronomicaldata, byvirtueofcollaboratingwidelyandinvest-ingeffortinprojects(suchasthe InternationalVirtualObservatoryAlliance(IVOA)) whichsupportandpromotedatasharing.

• Asaresultoftheintimaterelationshipbetweentherepository, theobserva-toryandtheuniversity(totheextentthattheboundariesbetweenthethreecanseemrathervaguetooutsiders), CDS personnelhavepracticalknowl-edgeofhowtheirdataisused, andwhatresearchersneed.

• ThecorefundingforCDS comesfromthefrenchstate, butitisconceivedasaninternationallyvisibleproject.

1.4.2 Collaborationsinastronomy

Themostvisiblecollaborationsinastronomyarelargeterrestrialandsatellite-bornetelescopesandotherinstruments. Attheriskofoversimplifying, thesearegenerallynotthemany-personcollaborationsusualin GW or HEP physics, butareinsteadfacilitiescreatedbyspaceagenciesorconsortiaofnationalfunders.Althoughtheyarehighlyinnovativeleading-edgefacilities, theyarenotseenasexperiments in thesamewayas LIGO or the LHC are (massive) itemsofspe-cialisedhardwarebuilttoansweradelimitedsetofscientificquestions. Theyareinstead observatories: thedatamanagementinthesefacilitiesispartoftheirgeneraloperatinginfrastructure, andtheresearchandresearchdatatheyproduceis‘owned’(atleastinanacademicratherthanalegalsense)bythescientist usersofthefacilities, ratherthanthefacilityitself.

Astronomydoeshoweverhaveavarietyofdata-analysiscollaborations. Thesearesemi-formalcollaborationsconcerned, mostly, withmulti-wavelengthstud-iesofmultiplearchives, and include forexampleUKIDSS-UDS, theHerschelAtlascollaboration, HerMES andGAMA.Thesehavebetween20and60collab-oratingmembersscatteredoverperhapsadozeninstitutionsbut, crucially, no‘corporate’existence, andlittleornodirectfunding. Instead, theyarefundedindirectlyviaindividualfellowshipsorrollinggrants: participationinthecollab-orationmightbeastrongfeatureofagrantapplication, butitisnotthecollabora-tionassuchthatreceivesthedirectsupport. Theydohavegovernancestructures,butthesetendnottobeparticularlyformal, becausetheyremainsmallenoughthatthereislittleperceivedneed. Thesecollaborationsexisttoderivehigh-valuederiveddataproductsfromthelower-leveldataproductsofthearchivestheyareanalysing(forexampleHerschelisan ESA observatorymission: thismeansthatindividualscanbidforobservations, butthatESA doesnothaveitaspartofitsremittoprovidemorethanminimallyreducedsciencedata).

Thecollaborationsdistributetheirresultsinpapers, andassociateddatasets;theytypicallybuildarchivestosupportanddistributetheirwork, butthere'snoexpectation(beyondtheusualcooperativeacademicnorms)thattheywillhelpothersworkonthedata, orreleaseit. Itishardtoseehowtherecouldbesuchanexpectation, muchlessanobligation, sincetheyreceivelittledirectfunding, and

12

http://www.nottingham.ac.uk/astronomy/UDS/

http://www.nottingham.ac.uk/astronomy/UDS/

http://www.h-atlas.org/

http://hermes.sussex.ac.uk/

http://www.gama-survey.org/


theirindirectfundingcomesfromamultinationalsetofentitieswithpotentiallyverydifferent DataManagementandPreservation(DMP) policies.

1.5 HighEnergyPhysicsdata

Astronomyisessentiallyanobservationalscience: telescopes, theiroptics, andthedetectorswhichhangoff them, areconstructed tocreateapath fromna-ture todatawhich isasnearlyaspossibleunmediated. Thismeans that it isbothreasonablyobviouswhatthingsaretobearchived, andthatthenatureandprocessingofobservationalartefactsarewellandcommonlyunderstood. Thismeansthatastronomy, unusualinthephysicalsciencesforneedingtopreservedatalong-term, isinthehappypositionofhavingitsdatareadilypreservable.

HEP dataisdifferent. HEP isaparticipativescience, whereobjectsranginginsizefromelectronsallthewayuptonucleiaredisassembled, anddataaboutthemessyresultsofthisdisassemblyisexaminedtoretrieveinformationabouttheinteriorstructureoftheoriginal. Thisreconstructionfromcollisiondatade-pendsonashiftingengineeringunderstandingofriversofdata, outofinstrumentswhichareone-offworksofart, designedandassembledbyathousand-strongcommunity, close-packedintoadetectorthesizeofasmallcathedral, attachedtoamachinewithitsownpostcode.

TheresultofthisisthatHEP dataanalysisisrathertricky, withmanystepsbetweendataandscience, eachofwhichdependsonsoftwarewhichencodesadetailedunderstandingofthedata'sprovenance. Inconsequence, althoughHEP dataistypicallydistributedwithmultiplelevelsofreduction, almostnoneoftheselevels(withtheexceptionofformalpublications)arestraightforwardlysuitableforlong-termpreservation. Thisisbecauseinterpretationofthisdataisheavilydependentonsoftware, theuseofwhichrequiresdetailedexperimentalknowledgewhichitmaybeinfeasibletopreserve. InOAIS terms, thedesignatedcommunityistinybecausethe RepresentationInformationishugelycomplex.

Inadditiontothis, HEP datahasaconsiderablyshortershelf-lifethanas-tronomydata, asdiscussedabove. Incontrast, oldHEP dataistypicallymaderedundantbynewdata, obtainedfrommorepowerfulaccelerators. Alsoincon-trasttoastronomydata, HEP dataisnotexpectedtobegenerallyintelligibleforverylong: two-orthree-decadeolddatamightpotentiallybeusefulorintelli-gible, butmuchbeyondthatwouldcountasarchaeology. Attheriskofbeingwhimsical, wecancomparetheroughlymillenniallifespanofastronomicaldatawiththeroughlythree-decadelifespanofHEP data, andconcludethatthelattergoes‘off’about30timesfasterthantheformer. Althoughfacilitiesmakeveryconsiderableeffortstomanagedatasafelywhileanexperimentisrunning, thereislittlerealpressuretopreserveHEP dataintothelongterm.

Ofcourse, thingsarenotquiteasstraightforwardasthatinfact. (i) The LHCgainsinteractionenergyattheexpenseofamessiercollision, sotherearepoten-tiallysomefeaturesthatwillbedetectableinonedataset(forexamplethe HERAp-edata)whichwouldnotbefindableintheLHC.Whileinteractionenergyisthemostprominentmetricofanaccelerator'sperformance, itisnottheonlyone,sothatlargeracceleratorswillnotrendersmalleronesobsoleteasinevitablyaswemayhavesuggestedabove. Similarlytothis, (ii) datareductionerrorsmaybedominatedbytheoreticaluncertaintiesratherthanexperimentalones, andthesewillonlybe improved, and thedata re-reduced, after theexperiment isover.Finally(iii) therearenoacceleratorsbiggerthantheLHC currentlyscheduled,sothatthisdatasetmayremainthehighest-energyoneforarelativelylongtime.Thearchaeologyisillustratedin [25]andtheproblemfurtherexploredin [26],whichalsodiscussestheHEP community'sdevelopingplansfordatapreserva-tion. Qualificationsnotwithstanding, theoveralltimescalesinHEP areshorterthaninastronomy, andthesolutionsdescribedin [26]areconcernedwithpro-longingacontinuouslow-levelrelationshipwithadatasetratherthanbeingable

13


http://www.pegasus.lse.ac.uk/research.htm andinparticular[28]

TheMOU whichcreatedtheLVC isat [31], butMOUsarenotroutinely

madepublic.

ThedefinitionofLSC membershipisincludedin [32]andthe

constructionoftheauthorlistin [33].

Theterm‘LVC’isnotaninitialism. Itcolloquiallyreferstothe

data-sharingagreement [31]andjointmeetingsbetweentheLSC and

theVirgoCollaboration. Thoughthereare‘LSC/Virgocollaborationgroups’, thereisnoformalbig-C

Collaboration.

toreturntoadatasetcold.Unlikeastronomy, HEP has for the last fewdecadesbeenorganised into

largerandlargercollaborations, andthesecollaborationshavedevelopedintri-cate, andsociallyfascinating, culturesformanagingthis. Thetwolargerinstru-mentsattheLHC, ATLAS and CompactMuonSolenoid(CMS),eachhaveauthorlistsoforder3 000people, sothatthevariousCERN collaborationsaccountforaround10 000research-activeindividuals. ThereisextensivediscussionofthehistoryandstructureoftheLHC collaborationsin [27]andintheoutputsofthePEGASUS project, butmanyofthecollaborations'relevantorganisationalfeaturesareechoedinthe GW community: thisisdiscussedinSect. 1.6.1 andwedonotdiscussthemhere.

1.6 Gravitationalwavephysics

Thegravitationalwavecommunityhasastronomicalgoals, butinthescaleoftheLIGO project, andintheamountofnoveltechnologyinvolved, aswellasinthefactthatmanyofthepersonnelinvolvedcameoriginallyfromaHEP background,theproject'sculturemorecloselyresemblesthatofaHEP experimentthanofanastronomicaltelescope. WediscusssomespecificfeaturesofLIGO datain [29];herewediscusswhere GW data, andthediscipline'sorganisationstructure, fitsonthespectrumbetweenastronomicalandHEP data.

1.6.1 Gravitationalwaveconsortia

TherearethreeprincipalsourcesofrecentGW dataavailabletoUK researchers:LIGO,GEO600andVirgo. Thereareotherdetectorswhichareeithersmallerefforts(intermsofconsortiumsizes), whichhavestoppedtakingdata(TAMA-300), orwhicharestillattheplanningstage. See [30]foranoverviewofcurrentdetectors, andofdetectorphysics.

LIGO LabisacollaborationbetweenCaltechandMIT,whichdesignsandrunsthreeinterferometersinHanford, WA,andLivingston, LA,intheUS. GEOisaGerman/Britishcollaboration, whichrunsthe GEO600interferometer. ThethreeLIGO interferometerswereshutdowninOctober2010torefitfor AdvancedLIGO (aLIGO);theGEO600interferometerisstillcurrentlyrunning. The LSC istheresultofanetworkof MemorandaofUnderstandingbetweenLIGO Lab(ormorelooselytheLSC) andmultipleotherinstitutionsofvarioussize. Thesere-lationshipsinvolvehardware, resources, anddataaccessofvarioustypes. Mosttypically, theresourcesinquestionarepersonnel, andaninstitutionsuchasauniversityphysicsdepartment, whichwishesaccesstoLIGO data, willcontributeinreturnfractionsofstafffrompermanentstaff, throughpost-docs, toPhD stu-dents, forabroadspectrumofactivitiesincludingdataanalysis, instrumentfabri-cationandshift-workinthedetectorcontrolroom. Howeverinsomecases, theMOUsareconcernedwithdataswaps, andsetuplimiteddatareleaseswithotherscientists: forexample, thereareafewMOUsbetweentheLSC,Virgoandotherobservatories, whichdescribewhatdataistobeshared, inwhatvolumes, andtheoutlineauthorshiparrangementsforanysubsequentpapers. GEO'sMOUdescribesaparticularlycloserelationshipwithLIGO Lab, butmostoftheMOUsarebroadly similar toeachother, and theprocessof creatingone isbynowstreamlined. In total (asof June2010), theLSC consistsofa littleover1300‘members’; ofthese, 615spendmorethan50%oftheirtimededicatedtotheprojectandsohaveaplaceontheLSC authorlist.

Theterm‘LIGO’hasanumberofnotquiteequivalentmeanings: sometimesitreferstoLIGO Lab, sometimestoLIGO LabplustheLSC,andthephrase‘LIGOdetectors’isgenerallyunderstoodtorefertotheLIGO LabandGEO detectors.

TheItalian/French Virgoconsortiumhasitsowndetectorandanalysis pipeline,andhasadata-sharingagreementwiththeLSC,representedbythe LVC.Aswith

14

http://www.pegasus.lse.ac.uk/research.htm

http://www.pegasus.lse.ac.uk/research.htm


LSC

otherinstitutions

Virgo

LVC

UK DEUSA (NSF) FR IT other EU

$ £ € €

LIGO Lab GEO

Figure 1: TherelationshipsbetweenvariousGW consortia.

LIGO,theVirgodetectorwillshutdownbetween2011androughly2015. Virgohas246members(withaslightlydifferentdefinitionfromtheLSC),andGEO600around100.

ThereisanattempttosummarisetheserelationshipsinFig. 1.Theseexperimentshaveacommonpurpose: theyexisttodetectsignatures

ofgravitationalwaves, whichareconfidentlypredictedbytheGeneralTheoryofRelativity, buttheactualobservationofwhichwouldbeamajorscientificevent(thereexistsanLSC dataprocessingflowchartwhichincludesthenotentirelyseriousbranch“CallStockholm!”).

Gravitationalwavesaresufficientlyweak, however, thattheexistingequip-mentwillnotbecomesensitiveenoughtohaveagoodchanceofdetectingthemuntilafteritsrefit, whichbeganinlate2010(whentheprojectenteredthephaseknownas aLIGO),andwhichisscheduledtobecompletedwhenthenewde-tectorsarecommissionedin2015.

1.6.2 GW data

Althoughtheconsortiahave(asexpected)announcednodetectionsofar, theynonethelessproducealargevolumeofauxiliarydata, representingbackgroundandcalibrationsignalsofvarioustypes, andthis, togetherwiththecoredata,means that theLSC collectivelyproducesdataata rateofapproximatelyonePB yr−1.

WecanreadilyidentifythelevelsofdatawhichwerediscussedinSect. 1.4:

Rawdata Thelowest-levelGW dataconsistsofthesignalsfromthecoredetec-tors. Thisdataismademeaningfulonlybyprocessingwithsoftwarewhichiscompletelyspecifictothedetectorsinquestion. Thisisstoredin‘frameformat’, which isaverysimple format intelligible toall theprimarydataanalysissoftwareinthecommunity, andwhichismultiplyreplicatedacrossNorthAmerica, EuropeandAustralia. Althoughthediskformatiscommon,thesemanticcontentoftherawdataisspecifictodetectorsandsoftware, sothatpreservingitlong-termwouldrepresentasignificantcurationchallenge.

Dataproducts Therawdataisprocessedintocalibrated‘straindata’, whichisthedatachannel inwhichaGW signalwill eventuallybe found (this ispossibly, butnotnecessarily, alsoheldinframeformat). Thisistheclassofdataproducts whichwilleventuallybemadepublic. Unusually, itturnsoutthatGW rawdataisinasemi-standardformat, andthedataproductsarespecifictotheanalysis pipelinewhichproducedthem.

Publications Sittingabovethedataproductsisaclassofhigh-leveldataprod-ucts, scientificpapers, andotherpeer-reviewedoutputs. TheGW projectshaveannouncednodetectionsofgravitationalwaves, buthavenonetheless

15


http://www.ligo.org/about/join.php

producedabroadrangeofastrophysicallysignificantnegativeresults [30,§6.2].

AswiththegeneralastronomydataproductsdiscussedinSect. 1.4, thedis-tinctionbetweenthe‘rawdata’ andthe‘dataproducts’ isthatthelatterdatasets,alongsidetheirsupportingdocumentation, willbeavailableforuseandreusebyscientistswhodonothaveanintimateconnectionwith, andknowledgeof, theinstrument.

Boththe‘dataproduct’and‘publication’groupsarebroadclassesofobjects.Thepracticalboundarybetweenthemisclear, however: whatwearecalling‘publications’areentitiessuchasjournalarticlesorderivedcatalogueswhoselong-termcurationisnottheresponsibilityoftheLSC dataarchive, thoughtheymaybeheldinsomeseparateLSC paperarchive, whichisassuchoutofscopeforthisproject.

1.6.3 Gravitationalwavedatareleases

BecausetheLSC hasnotannouncedthedetectionofanysignalsofar, andbe-causethedatawillremainproprietarytotheconsortiumuntilwellaftersuchanannouncement, therearenodistributeddataproductssofar, andsotheissuessurroundingformatsanddocumentationhavenotyetbeenaddressed. Howeveritistheeventualpublicdataproductswhicharethehighest-valueoutputsfromtheexperiment, andwhicharetheproductswhichitwillbemostimportanttoarchiveindefinitely.

Atpresent, LIGO dataisavailableonlytomembersofthe LSC.This isanopencollaboration, andresearchgroupswhichjointheLSC haveaccesstoallof the LIGO data. Inreturn, theycontributepersonnel to theproject (includ-ingforexamplepeopletodoshift-workmanningthedetectors), andacceptthecollaboration'spublicationpolicies, which require thatallpublicationsbasedonLIGO dataarereviewedbytheentirecollaboration, andcarrythecomplete800-personauthorlist. Atpresent, andinthefuture, datawhichisreferredtobyanLSC publicationismadepubliclyavailable. SeeSect. 3.3.2 forfurtherdetailsonLIGO's DMP plan.

1.6.4 Summary: big-sciencepreservationchallenges

Inthethreesectionsabove, wehavetriedtodescribebothdifferencesandcom-monalitiesbetweenthreelarge-scalescientificdisciplines. Possiblythebiggestdifferencebetweenthethreeareasisthathigh-levelastronomicaldataproductsaremuchmoregenerallyintelligiblethaneventhehighest-levelHEP products. Ineachcase, however, wehavealadderofreasonablywell-defineddataproducts,witheachrunggeneratedfromtheloweronesbysophisticateddatareductionpipelines.

Thesituationisnotasrosy, fromthepointofviewoflong-termpreservation,asthisaccountmaysuggest. Becausethepipelineshavedevelopedorganicallyoveranumberofyears, undertheinfluenceofexperiencewithearlierversionsandincreasedunderstandingoftheinstrument, theknowledgetheyrepresentissometimesencodedwithintheminalessstructuredwaythanwouldbedesirable.Sometimes, metadataisencodedinfilenames, orinconfigurationfiles, orwikis,orevenprivateemails. Ofcourse, onecouldsimplyarguethatthisinformationshouldbedocumentedbetter, butitwouldbehardtoarguethatthecostsofthisworkwouldbejustifiable, toserviceafuturetheoreticalneedthatfewbelievewouldevenbecomeanactualone. Inconsequence, althoughtheresultingdataproductwillberegardedasperfectlyreliable, itmaybeinfeasibletoredotheanalysisotherthanbypreservingandrerunningthepipelinesoftware(evenifitwerefeasible, itwouldbeprohibitivelyexpensive, andrarelyseenasvaluable;

16




seealsoSect. 2.4). Forthisreason, softwarepreservation hassomeroleintheoveralldatapreservationstrategy. Howeverit isnotcleartouswhatthisroleshouldbe, andthethornyissueofsoftwarepreservation isaddressedatgreaterlengthinSect. 3.2.

1.7 A contrast: socialsciencedata

It is possibly instructive to contrast thedatamanagement practices discussedhere, withtheverydifferentproblemsfacedbydatamanagersinthesocialsci-ences. In [34], theauthorssurveyanumberofsocialscienceprojects, withaparticularfocusontwolarge(forthesocialsciences)programmesfundedbytheEconomicandSocialResearchCouncil(ESRC) (theUK socialscienceresearchcouncil)withsubstantialresponsibilitiesfordatapreservationandsharing.

For theESRC projects, theartefactsbeingstoredaresimplethings, at thelevelof ContentInformation: theyareconventionalWorddocumentsandaudiofiles, ratherthantheheavilystructuredandstillsomewhatexperimentalbigsci-encedataobjects. TheESRC archivecontentswillremainbroadlyintelligibletofutureresearchers, withoutmucharchive-specificefforttodefine RepresentationInformationora DesignatedCommunity. Incontrasttothissimplicity, however,theESRC archiveshavetocopewithabroadrangeofassociatedcontextualis-ingmetadata, whichisdifferentfordifferentprojects, andinconsistentlyorin-completelyspecifiedbytheoriginatingresearchers, perhapsasanafterthought.Thismakesarchiveingestacomplicatedproblem, incontrasttothebigsciencecases, wherearchiveingest fundamentallyinvolveslittlemorethancopyingaself-containedsetofartefactsfromworkingstoragetosomepreservationstore.Inparticular, theESRC projectshaveacomplicatedsetofanxietiesaboutcopy-right, IPR,confidentiality, anonymizationandconsent; while LIGO caresintri-catelyaboutdataaccessandsecurity, itdoessointheratherformalcontextofprofessionalethicsratherthanfamilysecrets.

Thisillustratestwofurthernotabledifferencesbetweenphysicalsciencedataandthatofsocialscienceorbroaderarchivalresources.

Firstly, theresponsibilityforESRC datainpracticelieswithmorejuniorre-searchers, helpedbypart-fundedarchivists [34, §§5.2.1&5.4]. Forbigscienceprojects, itisfundersandseniorcollaborationmemberswhodrivethepreserva-tionefforts.

Secondly, essentiallyallphysicsdataisborndigitalandcomplete, mean-ingthatalloftheinformationtobearchivedispresentatthetimeofdeposit. Ofcourse, thisisnotcompletefromthepointofviewofreproducibility(thatrequiresjournalarticlesandpersonalknowledge)anddoesnotdiscountthesubsequentadditionof subjectivemetadataasfindingaids, but it iscompletely specifiedfromthepointofviewofconventional futureanalysis. Thedistinctionis thatexperimentaldataisacompleteandobjectiveaccountofeverythingthatwasbelievedtoberelevantinrecordingaphysicaleventwhichhappenedataspe-cifictime. Onecandisagreewiththeexperimenters'beliefsaboutcompleteness(thisshadesintoquestionsofreproducibilityandtacitknowledge), complainthatsomedetailsmightberecordedinnotebooksratherthandigitalrecords(moretrueoflab-scalethanfacility-scaleexperiments), orinextremecasesargueaboutthenatureofobjectivity, butanaturalscienceexperimenthasamuchclearerboundary, inspace, timeanddocumentaryextent, andsoamorenaturalexpec-tationofdocumentarycompleteness, thanwillbeusualforanexperimentinthesocialorhumansciences. Thisisdifferentfromthetraditionalarchiveproblem,wheretheproblemsofinterpretationaremorevisibleandacknowledged, andtheproblemofincompletenessmoreevident.

ThesummaryisnotthattheESRC orthebigsciencearchiveshaveaneasierjoboverall, butthatthecomplicationsexpressthemselvesindifferentpartsofthemappingfromOAIS abstractionstolocalfact. Bigsciencearchivesmustpreserve

Thisworkwaspartofthe‘DataManagementPlanningforESRCResearchData-RichInvestments’project(DMP-ESRC)(http://www.data-archive.ac.uk/create-manage/projects/JISC-DMP),fundedbyJISC,likethepresentproject, aspartoftheManagingResearchDataprogramme.

Foravividandilluminatingdiscussionofthecomplicationsandphysicalityofreproducingexperiments, see [35]andreferencestherein(bycoincidence, thisdescribesobservationsamongstgravitationalwaveexperimentersinGlasgow); thatdiscussionisreprisedinalargercontextin[6, ch.35]. Thequestionoftacitknowledgeisdiscussedatlengthin [36]. Foradiscussionofdifferenttypesofreuse,see [37, §3].

17

http://www.data-archive.ac.uk/create-manage/projects/JISC-DMP

http://www.data-archive.ac.uk/create-manage/projects/JISC-DMP


Figure 2: Calculatedephemeris for theperiod104 BCE March23to101 BCE

April18, writtenonSeleucidyear209, monthIX,day18(103 BCE December20?). ComparisonwithaJPL ephemerisshowsthatthetextconjunctiontimesremainwithinacoupleofhoursofthecorrectvalues, withanoffsetattributabletoanerrorintheinitialvalue. Fordetaileddiscussion, see[40]. BritishMuseumitemSp-II.52, ©TrusteesoftheBritishMuseum.

See[38]forbackgroundandfurtherreferences, and[39, ch.4]forverydetaileddiscussionofthephysical

tablets. Theprecisedateoftheobservationsisofconsiderable

scholarlyinterest, sinceanagreeddatewouldprovideanabsolutefix

fortheotherwiserelativechronologyoftheLateBronzeAgeNearEast.

largecomplicatedobjectsforahard-to-describe DesignatedCommunity, butbe-causetheyareessentiallyalwaysproject-specificarchives, theirimplementationdoesnothavetobegeneric, andmanyoftheingestionissuescanbebakedintotheoriginalarchivedesign.

1.8 Babyloniandatamanagement(lesscontrastthanyou'dthink)

Contemporaryastronomybegan, inthewest, inMesopotamiainthefifthandfourthcenturies BCE. Althoughearlierdatasetsexist – the Venus tablet ofAm-misaduqa isaclusterof7th C BCE copiesof17thC or16thC datarecordingtherisetimesofVenusovera21yearperiod –theseearlieromentextsseemtohavebeenpreservedforlargelyculturalreasons.

Distinctfromthese, thereisalargesetof4–500othertexts, rangingfrom4thC BCE to75 CEwithasmatteringgoingbackasfarasmid-8thC BCE,andspan-ningthedevelopmentofBabyloniantheoreticalastronomyduringthe4thC BCE.Theseareamixtureofobservations, calculatedephemerides (suchasFig. 2),andtelegraphicallyobscuretechnicaldocumentation. Theobservationtexts –‘astronomicaldiaries’, formingthemajorityofthetexts –describeinsequencecelestialandmeterologicalobservations, dailycommodityprices, river levels,andtopicalevents. TheobservationsoftheSun, Moonandplanetswereofgoodenoughquality, andpreservedoveralongenoughtime, thatwhenbabylonianmathematicalmodelswerefittedtothemtheyproducedvaluesforthesynodicandanomalisticmonthsand(implicitly)theorbitalperiodsoftheplanets, whichareveryrespectablyclosetotheircurrently-determinedvalues(outbyafactorof3× 10−7, inthecaseofthesynodicmonth). Thesewereusedtopredictthefirstandlastappearancesofplanets, andthetimesoflunar(butnotsolar)eclipses.

The information in these texts issometimesavailableonmultiple tablets,althoughitisnotclearwhethertheseduplicateswerebackups, mirrors, ormediarefreshes. Manytabletshaveacquisitionmetadata, addedininkbythearchives,millenniaapart, inBabylonandBloomsbury.

Itisclearthatthetabletsthathavesurvivedrepresentonlyasmallfractionofthetotal. butboththedata, andthemathematicaltechnologythatreducedthedataandgeneratedtheephemerides, wereavailableandfullyintelligibleto

18


Hipparchus (c 150 BCE) and, eitherviahimordirectly, toPtolemy (c 150 CE).TheBabylonDataCentrewasstillactiveinthefirstcentury CE,thoughfundingcutsmeantnewacquisitionswerebythenminimal, anditwasoperatinginthecollapsingruinsofthedesertcity.

The Content Information in the texts is sufficientlywell preserved that ifthetextscanbedatedatall(insomecasesthroughcontemporaryingestmeta-data), theycangenerallybedatedtotheveryday; thetechnical RepresentationInformation, incontrast, issoterseas tomakesenseonlyafter theprocedurebeingdocumentedisreconstructedfromtheContent. Thecuneiformpresentsachallenge, butoncethishasbeentransliterated, thedatasetsarefundamen-tally intelligible tocurrent astronomers. Thepreservation strategy is adaringone: byeffectivelyfoundingwesternastronomy, andarrangingthatthedatawaspreservedjustlongenoughthatitcouldbetakenoverbythe(hellenic)succes-sorcivilisation, thebabyloniansensuredthattheircoordinatesystem(basedonthezodiac)andnumbersystem(withanglesindegrees, subdividedintobase-60fractions)wouldstillbeinusebyastronomers25centurieslater.

1.9 Bibliographicrepositories

Thoughitisnotstrictlydata, itseemsusefultomakeparentheticalmentionofthebigsciencecommunities'literaturerepositories, sincetheyseemtoillustratethewayinwhichthecommunitieshavelearnedtoactcollectively.

Thepreprintarchiveat arXiv.org startedin1991asanelectronicversionofthelong-establishedpracticeofdistributingpreprintsofacceptedjournalar-ticlesaroundthehigh-energyphysicscommunity, bypost. Itcurrentlyreceivesaround6000submissionspermonth, predominantly inHEP,astronomy, con-densedmatterphysicsandmathematics; itprobablyreceivescopiesofnearly100%oftheHEP community'soutput. Authorsmosttypicallysubmitpapersatthepointwhentheyhavebeenacceptedbythejournal, butsomesubmitearlierversions, andafewarenotfurtherpublishedatall. Althoughthejournalsarestillprovidingan imprimatur, manypapersarenowprincipallyreadaspreprints, andmanyjournalspermitcitationsbyarXivreference. ArXivissupportedbyrequest-ingcontributionsfromitsheaviestinstitutionalusers, onaslidingscalerisingto$4 000/year. JISC Collectionsisoneofthese‘tier 1’supporters, onbehalfofUKcollegesanduniversities.

TheNASA ADS attheSmithsonianAstrophysicalObservatorypreservesbib-liographicinformationfortheastronomyliterature, holdsreferencestoorcopiesofjournalarticlefulltexts, andcuratesdigitisedcopiesofolderarticlessometimesunavailablefrompublishers. ItalsocurateslinksbetweenthesepublicationsandthearXiv, andbetweenpublicationsanddata. See [41]forcontext, andsomediscussionofthearXivnumbersmentionedabove.

ThepublicationparadigmrepresentedbyarXiv (andsimilarsmaller-scaleefforts) isunderpinnedby thepeer reviewprocessesof journals. Howeverasjournalsubscriptioncostsrise, journalsareprogressivelycancelled, inaprocesswhichmayultimately damage the reviewingprocess onwhich theparadigmdepends. TheSCOAP3 consortiumaimstobreakoutof thiscyclebydirectlysupportingasmallnumberofHEP journals, throughalevyonthefundingagen-cieswhichsupportthefield, inproportiontotheshareofHEP publishingtheysupport. Inreturnforthisthejournalswillremovebothsubscriptionchargesandpagechargesforthesejournals.

1.10 VirtualObservatories

A VirtualObservatory isanastronomicaldata-sharingsystem, composedofanetworkofarchivesanddata-accessprotocols. Thegoalisthatthedataappearstobeintegratedandideallyappearstobelocal.

Thiscanbeclassedasa‘high-risk’datapreservationstrategy, andisnotincludedamongstthisreport'sRecommendationstoSTFC.

http://arxiv.org/Stats/hcamonthly.html

http://arxiv.org/help/support/whitepaper

http://scoap3.org/about.html

19





http://scoap3.org/about.html


http://www.astrogrid.org,http://www.usvao.org/, and

http://www.euro-vo.org; plushttp://www.ivoa.net.

Seefurthercommentaryinhttp://lwsde.gsfc.nasa.gov/VxO_

Report_Decadal_Survey_5_2011.pdf

http://www.helio-vo.eu andhttp://lwsde.gsfc.nasa.gov/


Theearliest VOswereAstrogrid in theUK, theUS-VO in theUS (whichbecameNVO andthenVAO),andtheAstrophysicalVirtualObservatoryinEu-rope(whichbecameEuro-VO).They, alongwithagrowingcollectionofsmallernationalorregionalVOs, formedthe IVOA in2002. TheIVOA existstobrokerportablenetworkprotocolsforsharingdata, onthepartofcooperatingarchives,andaccessingit, onthepartofclientapplications. TheIVOA focusesprimarilyon‘traditional’astronomy, andsohaspoorcoverageofsolarphysicsandmorebroadlygeophysics(andcertainlyprovidesnoaccesstoGW data).

Fromthishasgrownthemoregeneralnotionof the ‘VxO’, whichis“[a]servicethatensuresthatallresourcesfromsub-field x areknown, discoverable,andeasilyaccessible. Itlookstotheuserlikeauniformdataprovider, butitisvirtual.”ExamplesincludetheVirtualSolar-TerrestrialObservatory [42], HELIO,andNASA'sHeliophysicsDataEnvironment.

1.11 Dataproductsandproprietaryperiods: reifyingdataman-agementandrelease

A commonfeatureofthevariousdatastylesaboveisthenotionofthe dataprod-uct, anditseemsusefultorecapandstressthesalientfeaturesofthishere.

Dataproducts: A dataproductisadesignedanddocumentedoutputofaninstrument, intendedtobebotharchivableandimmediatelyusefultootherresearchers, byvirtueofhavingobservationalartefactsremovedasmuchaspossible.

Dependingonthedisciplineandtheengineeringcomplexityoftheinstrument,dataproductsmaybeanythingfromtherawdatatoahighlyprocessedderivativeof the rawdata; the idealdataproductcontainsall the scientifically relevantinformationwithnoneoftheexperimentalartefacts.

Researchersarenotrestrictedtousingonlydataproducts, butitwillonlyrarelybenecessaryforthemtoresorttoreanalysingrawdata(seethediscussiononp.10).

Dataproductscorrespondcloselytothe‘InformationPackages’oftheOAISmodel(seeSect. 3.1.1). Inourexperience, theretendstobelittlepracticaldiffer-encebetween SubmissionInformationPackages(SIPs)and ArchivalInformationPackages(AIPs), andwheretherearedistinct DisseminationInformationPack-ages(DIPs), theytendtobeavailableinadditiontotheavailableSIPsandAIPs.AnexceptiontothisisarchivessuchastheWide-FieldAstronomyUnitatEdin-burgh, whichspecialisesinastronomicalsurveyscience, anddevelopsenhancedarchives(whichistosay, value-addedAIPs)aspartofitsparticipationincollab-orativeastronomyprojects.

WhenthevariousPackagesdiffer, theytendtoberegardedassuccessivelyhigher-level, asopposedtoalternative, dataproducts.

Thenotionofdataproductshasanumberofconcreteadvantages.

• Mostimmediately, theexistenceofastableanddocumentedoutputmakesiteasierforresearcherstouseandrepurposeexperimentalandobservationalresults.

• Becausetheproductsaresocentraltoaninstrument'soutput, they, andthepipelinesthatproducethem, aredesignedandcostedatearlystagesofaninstrument'sproduction.

• Researcherscanproduceandsharesoftwarewhichprocesseswell-definedproducts, possiblyfrommorethanoneinstrument.

• Because theyaresoexplicit, they formwell-definedstartandendpointsofdiscussionsaboutinteroperabilitybetweeninstruments. Indeed, the VO

20

http://www.astrogrid.org

http://www.usvao.org/

http://www.euro-vo.org

http://www.ivoa.net

http://lwsde.gsfc.nasa.gov/VxO_Report_Decadal_Survey_5_2011.pdf

http://lwsde.gsfc.nasa.gov/VxO_Report_Decadal_Survey_5_2011.pdf

http://www.helio-vo.eu

http://lwsde.gsfc.nasa.gov/



programmecouldbecharacterisedasanextendedefforttonegotiatenewcommonproductswhicharchives and softwaredevelopers agreecanbesuccessfullygenerated(byarchives)fromexistingAIPs.

There isofcourseacostassociatedwith thedesignanddevelopmentofdataproducts, butwebelievethatthiswillinmostcasesbemuchsmallerthanthecostsassociatedwiththeretrospectivedocumentationanddistributionof adhocdatasets.

Anothernotionthatiswell-knowninthephysicalsciences, butwhichasfarasweareawareisrareoutside, isthatofexplicit proprietaryperiods fordata.

Proprietaryperiod: A ‘proprietaryperiod’isaperiodafterdataisacquired, andthereforearchived, byasharedinstrument, duringwhichitisprivatetotheobserverorobserverswhorequestedit, andafterwhichthedata(usuallyautomatically)becomespublic.

The term ‘embargoperiod’wouldpossiblybemoregenerally intelligible, but‘proprietary’isconventional. Thenotionisdiscussedelsewhereinthisdocument(seeforexampleSect. 1.4), butwestressitherebecauseitusefullyconcretizesanumberofotherwisevaguequestionsaboutdatarelease.

Insteadofratherbroadquestionsofthehow, when, whyandwhetherofdatamanagementandrelease, weinsteadhavequestionssuchas‘whatarethedataproducts?’, ‘whomaretheydocumentedfor, andhowexpensively?’, ‘howlongistheproprietaryperiod?’or ‘whatis thequidproquofor thisperiod?’Thesequestionsdon'tmagicallybecomeeasytoanswer, buttheybecomealoteasiertoask, andinviteconcreteanswersandnegotiationratherthan adhoc argument.

There is nothing in thenotions of data products andproprietary periodswhichisobviouslyspecifictothephysicalsciences. Thenotionshavebecomewell-establishedinthisareaprobablybecauseithaslongexperience, ofneces-sity, ofusinglargesharedinstrumentswhichareoperatedtoagreaterorlesserextentasservices. This is lessoftenthecaseindisciplineswithmorebench-scaleexperimentalnorms, butevensomeareasofbiologyarenowmoreoftenusingsharedfacilities, andinotherdisciplines, dataproductsandproprietaryperiodswouldbecomemorenatural, themorethatpreservation-awarestorageisused [43].

Wecommend thenotionsofdataproducts andproprietaryperiods, andthedata culture they engender, to thebroader research community. Indeed,werecommendthat datamanagersshouldconsideradoptingthelanguageofdataproductsandexplicitproprietaryperiodswhendesigninganddocument-ingtheirholdings.

2 Theresponsibilitiesfordatapreservation

2.1 Visualisingbenefits

Whydofunderswishtopreservedata? Becausetheyperceive benefits tothatpreservation.

Buildingonthistruism, itseemsusefultoexplicitlyarticulatethesebene-fits. The JISC-fundedproject KeepingResearchDataSafe (KRDS) (see http://www.beagrie.com/krds.php and [44]) described a collectionof studies and toolssupportingdatapreservation. AmongsttheKRDS innovationswasatypologyofbenefits, describingthreedimensions: directtoindirect, near-tolong-termandpublictoprivate. InaslightextensiontotheworkinKRDS,wecantaketheno-tionof‘dimensions’perfectlyliterally, assignanyparticularbenefittoapositionalongeachofthethreeaxes, andplottheresultinathree-dimensionalspace;seeFig. 3 onthenextpage.

ComparethecommentsaboutHerscheldatainSect. 1.4.

Recommendation1

21

http://www.beagrie.com/krds.php



(unlessit's otherpeople's opendata,ofcourse)

http://www.scitech.ac.uk/rgh/rghDisplay2.aspx?m=s&s=64

Metadata

Open data

Sysadmins

DR software

Researchers

Collaborations Institutions

Funders

Figure 3: Visualizingbenefits

Inthisfigureweidentifyfourbenefitswhichmightbeassociatedwithabig-scienceproject –namelytheexistenceofdata-reductionsoft-ware, goodmetadata, theprovisionofopendataandtheexistenceofsystemadministrators –andwesketchtheapproximatevolumestheymightoccupyalongthethreeaxes(inblue). Onthesamediagram, wecanindicate(inred)theapproximateareasofinterestoffoursamplestakeholders.

Intheexamplehere, ‘sysadminsupport’canbeseenasanindirectbenefit to researchers, typicallyprivate toan institution, butcreatingvalueinthenear-andlongterm; itisthereforespreadalongthe‘near-longterm’axis, butatoneextremeoftheothertwodimensions. Wecanputonthesamediagramtheapproximateareasofinterestofvar-iousresearchstakeholders. Forsimplicity, wearehereconceivingofindividualresearchersasselfishandshort-termist, thoughthesamere-searcherswillhavelong-terminterestwhentheyhaveacollaborationorinstitutionalhaton, andindirectpublicinterestsinthelong-termhealthof theirdisciplinewhentheyareservingonafundingcouncilgrantspanel; belowwewilltaketheterm‘funders’toreferbothtotheofficialsoffundingbodies, actingasproxiesforthewiderinterestsofsociety,andtomembersoftheresearchcommunitydischargingserviceroles.

Weshouldnottakethisdiagramtooliterally –itisnotclearthattheaxesare independent, and theextentandeven thegrosspositionsof thevariousinterestsandbenefitsaredebatable. Thediagramisnonethelessthought-provoking. Forexample, itvisuallypredictsthatmuchoftheresearchcommunityisnotparticularlyinterestedin‘opendata’andonlyincompletelyinterestedin‘goodmetadata’(in-collaborationresearcherscarewhenadatasetwasacquired,becausetheyneedthatinformationtoperformtheiranalyses, buttheyhavelittleinterestindisseminationandlicensingmetadata, forexample, becausethatisthelong-termconcernoffundersandtheirproxies). Wecanthereforenaturallyconceiveofthefunderstakingtheroleoftheconscienceofadiscipline, worryingaboutlong-termimponderablessothatindividualresearchersdon'thaveto. Itfollowsfromthis, thattheopendatacasemadetofunders, forexample, willbeaninstitutionallyself-interestedone, butthatthecasemadetoresearchersmustbequalitativelydifferent, andbeeitherpragmatic(‘youmustcarebecauseyourfunderscare’)orhigh-minded(‘yoursocio-culturaldutyis…’). Neitheroftheseisapoorargument, norindeedacynicalone, butweareacknowledgingherethat, toabusyanddistractedresearcher, theself-interestargumentinisolationmayhavelittlepurchase.

2.2 Thecaseforopendata

Internationally, there isapushtowardssuch datasharingin themoregeneralcontextofscholarlyresearch(seeforexample [45]or [46]). Themostexplicitstatementhereisinthe NSF'sGC-1document [47], whichinsection 41statesthat“[NSF] expectsinvestigatorstosharewithotherresearchers, atnomorethanincrementalcostandwithinareasonabletime, thedata, samples, physicalcol-lectionsandothersupportingmaterialscreatedorgatheredinthecourseofthework. It also encourages grantees to share software and inventionsor other-wiseacttomaketheinnovationstheyembodywidelyusefulandusable.”Thisisreiteratedinalmostthesamewordsintheir2010datasharingpolicy [3]. Theyadditionallyrequireabriefstatement, attachedtoproposals, ofhowtheproposalwouldconformtoNSF'sdata-sharingpolicy.

STFC,incommonwiththeotherUK researchcouncils, requiresthat“thefulltextofanyarticlesresultingfromthegrantthatarepublishedinjournalsorconferenceproceedings[…]mustbedeposited, attheearliestopportunity, inanappropriatee-printrepository”; ithasnotyetmadeanycorrespondingstatement

22




ondatareleases.Theyear2009sawsomeexcitement(relatingtotheincidentinevitablyla-

belled‘climategate’, andtosomeotherdata-releasedisputes)relatedtotheman-agementandreleaseofclimatedata. Thisillustratedthepoliticalandsocialsig-nificanceofsomesciencedatasets; thecontrastbetweenwhatscientistsknow,andthepublicbelieves, tobenormalscientificpractice; andsomeoftheissuesinvolvedinthegeneration, ownership, useandpublicationofdata. Thecasesduringthatyearillustrateanumberofcomplicationsinvolvedindatareleases.

1. Data isoftenpassedfromresearchersorgroupsdirectly toothers, acrossborders, withnogeneralpermissiontodistributeitfurther.

2. Datacollectionmaybeonerous, andtheresultofsignificantprofessionalandpersonalinvestments.

3. Rawdata isgenerallyuselesswithoutthemoreorlesssignificantprocessingwhichcleansitofartefactsandmakesitusefulforfurtheranalysis.

4. Howevernotalldisciplineshavetheclearnotionofpublisheddataproductswhichis foundinastronomyandwhichis implicit intheOAIS notionofarchivaldeposit.

5. Scienceisacomplicatedsocialprocess.

Inscience, wepreservedatasothatwecanmakeitavailablelater. Thisisonthegroundsthatscientificdatashouldgenerallybeuniversallyavailable, partlybecause it isusuallypubliclypaid for, butalsobecause thepublicdisplayofcorroboratingevidencehasbeenpartofscienceeversincethemodernnotionofsciencebegantoemergeinthe17thcentury(CE) –witnesstheRoyalSociety'smotto, ‘nulliusinverba’, whichtheSocietyglossesas‘takenobody'swordforit’. Ofcourse, thepracticeisnotquiteassimpleastheprinciple, andahostofissues, rangingacrossthetechnical, political, socialandpersonal, complicatethesocial, evidentialandmoralargumentsforgeneraldatarelease.

Thearguments against generaldatareleasesarepracticalones: datareleasesarenot free, andmayhavesignificantfinancialandeffortcosts (cfSect. 3.4).Manyof thesecostscome from (preparation for)datapreservation, since it isformallyarchiveddataproductsthatarethemostnaturallyreleasableobjects:releasingraworlow-leveldatamay becheap, butmayalsohavelittlevalue, sincerawunderdocumenteddatasetsarelikelytobeuseless; ormorepessimisticallytheymayhaveanegativevalue, iftheyendupfosteringmisunderstandingswhicharetime-consumingtocounter(thispointobviouslyhasparticularrelevancetopoliticisedareassuchasclimatescience). Inconsequenceofthis, the‘opendataquestion’overlapswiththequestionofdatapreservation –ifthevariouscostsandsensitivitiesofdatapreservationaresatisfactorilyhandled, thenasignificantsubsetofthepracticalproblemswithopendatareleasewillpromptlydisappear.Wediscussthedatapreservationquestionbelow, inSect. 2.3.

Itseemsworthnoting, inpassing, thatthephysicalsciencesbroadlyperformbetterherethanotherdisciplines, bothinthetechnicalmaturityoftheexistingarchivesandinthecommunity'swillingnesstoallocatethetimeandmoneytoseethisdoneeffectively.

Whatallthisindicatesisthatthereisaneedforanexplicitframeworkfordiscussingthepragmaticsofopendata(cfpoint 4 above). Wecangofurtherandsuggest(itisalmostaRecommendation)thattheOAIS model'snotionofanAIP,anditsreflectioninthenotionofa dataproduct shouldbecentraltothisdiscussion.

http://www.guardian.co.uk/environment/2010/apr/20/climate-sceptic-wins-data-victory

UEA'sClimateResearchUnitisapartnerintheACRID project, alsofundedbytheJISC MRDprogramme: http://www.cru.uea.ac.uk/cru/projects/acrid/

Thelastpointissimultaneouslyobviousanddeeplyintricate.Unpackingitwoulddistractushere,butthereisfurtherdiscussion, inaveryappositehistoricalcontext,in [6], elaboratedin [36].

23

http://www.cru.uea.ac.uk/cru/projects/acrid/

http://www.cru.uea.ac.uk/cru/projects/acrid/


2.3 Thecasefordatapreservation

ThecasefordatapreservationinastronomywasimplicitlymadeinSect. 1.4:asanobservationalscience, muchastronomydataisrepeatable, butthereareimportantcaseswherewhatisbeingobservedisaslowsecularchange, orsomeunpredictable(usuallyultimatelyexplosive)event; sometimesdatacanbeop-portunistically reanalysed to extract informationdistinct from the informationtheobservationwasdesignedfor. Astronomicaldata ispotentiallyuseful andusablealmostindefinitely. Thusthereisareasonableexpectationthatthedatacanbeandwillbeexploitedbyunknownastronomers, farintothefuture.

HEP dataissomewhatdifferent(asnotedinSect. 1.5). Asanexperimentalscience, itisgenerallyverymuchincontrolofwhatitobserves, andisabletodesignexperimentsofconsiderableingenuity, inordertomakemeasurementsofexquisitediscriminatorypower. A consequenceofthisisfirstlythatHEP ex-perimentshaveamuchstrongertendencytobecomeobsoletewitheachtechno-logicalgeneration, andsecondlythatthecomplicationoftheapparatusmakesithardtocommunicateintothefuturealevelofunderstandingsufficienttomakeplausibleuseofthedata. Experimentalapparatuswillgenerallybeunderstoodbetterandbetterastimegoeson(thisisalsotrueofsatellite-bornedetectorsinastronomy), so thatdatagatheredearly inanexperimentwillbeperiodicallyreanalysedwith increasedaccuracy. However thisunderstanding isgenerallynotpreservedformally, butispragmaticallycommunicatedthroughwikis, work-shops, wordofmouth, configurationandcalibrationfiles, andinternalandex-ternalreports. Evenifallofthetangiblerecordsweremagicallypreservedwithcompletefidelity, andsupposingthatthemoreformalrecordsdocontainalltheinformationrequiredtoanalysetherawdata, anarchivewouldstillbemissingtheword-of-mouthinformationwhichanewpostgradstudent(forexample)hastoacquirebeforetheycanunderstandthemorecompletedocumentation. Wecanthinkof thisasa ‘bootstrapproblem’. InOAIS terms, the RepresentationNetworkforHEP dataisparticularlyintricate, andwhilethe RepresentationIn-formationnearesttothe DataObjectmaybecomplete, itmaybeinfeasibletogathertheRepresentationInformationnecessarytoletanaiveresearchermakesenseofit. The DesignatedCommunityforHEP datamaythereforebenullinthelongterm.

Thissoundspessimistic, but [26]describesanumberofscenariosinwhichHEP datacanandshouldbereanalysedsomedecadesafteranexperimenthasfinished, anddescribesongoingworkonthedevelopmentofconsensusmodelsforpreservingdataforlongenoughtoenablesuchpost-experimentexploitation.Thisprovidesastrongcaseforastyleofpreservationsomewhatdifferentfromtheastronomicalone. Whatthesemodelshaveincommonisacommitmentofstafftoactivelyconserveandcontinuouslyexploitthedata. Thispost-experimentstaffcanthereforebeconceivedasaformofwalkingRepresentationInformationsothat, whiletheyarestillinvolved, thedatamighthaveaDesignatedCommunitywhichcorrespondstothoseindividualsinapositiontoundertakeanextendedapprenticeshipinthedataanalysis(thismodelisfurtherdiscussedonp.32).

GW datais, asusual, somewherebetweenthesetwoextremes. Asastron-omy, theGW dataconsistsofunrepeatablemeasurementswhichwillpotentiallybeofvaluetoastronomerswellintothefuture; asaHEP-styleexperimentitmakesthosemeasurementsusingtwoorthreegenerationsofhighlysophisticatedappa-ratus, eachgenerationofwhichwillimproveonthesensitivityofitspredecessorsbyordersofmagnitude. Anadditionalfeature, however, isthatno-onehaseverconvincinglydetectedagravitationalwave, though therehavebeen repeatedclaimsofdetectioninthepast, sothatthefirstclaimsbyLIGO or aLIGO willbescrutinizedparticularlyclosely.

Finally, andasnotedinSect. 2.2, ifdataiswellarchived, thenmostofthepragmaticobjectionstoopeningthatdatadonotapply. Thus, totheextentthat

24


generaldatareleaseisagoodinitself, itisafurtherargumentinfavourofawellsupportedarchive.

2.4 Shouldrawdatabepreserved?

Inthedata-preservationworld, thereisoftenanautomaticexpectationthat‘ev-erythingshouldbepreserved’, sothatanexperimentcanberedone, resultsre-analysed, orananalysisrepeated, later. Isthisactuallytrue? Orifitisatleastdesirable, howmucheffortshouldbeexpendedtomakeittrue? Thisquestionisimplicitin, forexample, thediscussionofsoftwarepreservation inSect. 3.2.

Whenaphysicalexperimentissetupandworking, itisusualtoavoidtin-keringwithitasmuchaspossible, toavoidanyunexpectedlysignificantchange.That is, evenwithasmall-scale lab-benchexperiment, it isaccepted thatnoteverythingcanbeeffectivelydocumented, and that anexperimentmightnotbeimmediatelyreplicablepurelyfrompublishedinformation(cf[6, ch.35]andSect. 1.7). Thisexpectation(orrather, lackofexpectation)isalsotrueoflarger-scaleexperiments, whichmightbefinancially, professionallyor, at thelargestscales, politicallyinfeasibletoreplicate. Perhapsthisattitudeshouldextendtootheraspectsoftheexperimentalprocess.

Inmanycases, thepipelineforreducingrawdataseemstofallintothiscat-egory: itencodeshard-to-documentinformation, butisitselfhardtodocument,hardtouse, andunlikelyevertobereusedinfact. Ifthissoftwareisnotpreserved,thentherawdataiseffectivelyunreadable, whichmeansthereisnocaseforpre-servingit. Thereisthereforeacasethatatleastsomedetailsoftheexperimentalenvironment –digitalaswellasphysical –arenotreasonablypreservable, andthatasaresultlittleeffortshouldbeexpendedonpreservingthem.

Itisdataproducts thatmakerawdatalessnecessary. Itisfeasibletodoc-umentthescientificmeaningofdataproducts, andthecommunityexpectsthataprojectwillprovidethisdocumentationaspartofthepublicationoftheprod-ucts(indeed, itthedocumentationthatmakesthese products ratherthanjustacasualdatasnapshot). Thedataproductsallowresearcherstodigbeneaththeconclusionsofaparticulararticle(orindeedthecontentsofahigher-leveldataproduct), andtocriticiseandbuildonwhattheyfindthere. Higher-levelprod-uctsaretheresultofhigher-levelscientificjudgements, anditisnormalforthesetoberegeneratedbyresearchersotherthantheoriginators, eitherusingtheirownsoftwareortheoriginators'pipelines. Theselater-stagepipelinesaremorefor-mallysupportedbyprojects, whichinvolvesmakingthemreasonablyportable,sothattheyarebotheasiertopreserveaswellasbeingmorevaluableobjectsofpreservation.

Weshouldstressthatwearenotadvocatingdeliberatelydeletingrawdata,anditsassociatedpipelines –it might beuseful, andit might beusable –butsimplynotingthatoneshouldnotoverstateitsvalue.

2.5 OAIS:suitabilityandmotivation

InSect. 3.1.1, weprovideanoverviewoftheOAIS model, anddescribehowitrelatestoastronomicaldata.

TheOAIS standardisformallyaproductofthe ConsultativeCommitteeforSpaceDataSystems (CCSDS),andwith this in its lineage it isquitenaturallymatchedtothedatamanagementproblemsofthephysicalsciences. EssentiallyalltheexplicitandimplicitassumptionsoftheOAIS standardaretrueintheareawearestudying: thedataproducer(asatelliteoradetector)isusuallyobvious,thevarious InformationPackages (ordataproducts)wellunderstood, and theDesignatedCommunityeasilyidentified.

Themotivationforadigitalpreservationstandard, asdiscussedintheOAISstandarditself [4, §2], isthatdigitalpreservationrepresentsadoubleproblem:

Itisbecauseverylarge-scaleexperimentsareimpossibletoreplicate, andevenhardforanexternalreviewerofanarticletocriticisemeaningfully, thatlargecollaborationssubmittheirpublicationstoextremelyscrupulousinternalreview. Seehttp://stuver.blogspot.com/2011/03/big-dog-in-envelope.html forapost-mortemaccountofsuchareview.

http://www.ccsds.org

ThereisnocontradictionherewiththeremarksinSect. 1.7 aboutthedifficultyofdescribingtheDesignatedCommunityofsciencearchiveusers. ItiseasytonameascienceDesignatedCommunity, butitmaybehardtodescribeaheadoftimewhatthosecommunitymemberscanbeexpectedtoknow.A socialsciencearchivemayhaveanunpredictablybroadrangeofultimateusers, butusingthearchivewillneedlittlespecialistknowledge;incontrastaparticlephysicsdatasetwillprobablybeofinterestonlytoparticlephysicists, butthenormaleducationofsuchaphysicistthreedecadeshence, andthusthecontentandextentofthespecialisedRepresentationInformationthatCommunitywillneed, mightbeveryhardtoguessat.

25

http://stuver.blogspot.com/2011/03/big-dog-in-envelope.html

http://stuver.blogspot.com/2011/03/big-dog-in-envelope.html



Recommendation2

Recommendation3

(i) digitalinformationisintrinsicallyhardertopreservethantraditionalinforma-tion, whichiscapableofsittingonashelfinawell-understoodandintelligibleformat, andmoulderingatawell-understoodandgracefulrate; and(ii) moreandmoreorganisationsareproducingdigitalinformation and areimplicitlyexpectedtoarchivetheirownmaterial. Thismeansthatthesenon-specialistarchiveshaveacomplicatedtasktoperform, whichispotentiallyatoddswiththedailyurgen-ciesoftheirmainbusiness.

This appears tomeaninturn(andinJISC contextsitisoftentakentomeaninpractice)thattheseorganisationsneedasmuchdetailedandprescriptivehelpaspossible, ideallydevolvingtheirarchiveresponsibilitiestoacentraldiscipline-orfunder-specificarchive, totheextentpossiblewhilerespectingthelow-levelcomplicationsandfrictionalludedtoinSect. 1.7. Thisisnotthemodelwhichisappropriateforbig-sciencedatasets.

2.6 Whatshouldbig-sciencefundersrequire, orprovide?

Wehavedescribedseveralcommonfeaturesofbig-sciencedatamanagementinSect. 1.3. andwehaveoutlinedsomeparticularcontrastswithothercommuni-tiesinSect. 1.7. AsnotedinSect. 0.1, ourfocushereisonSTFC'sstrategicallyfundedprojects, ratherthanthesmallerprojectsfundedbyindividualresearchgrants.

Big-sciencedatasetsaregenerallyintimatelycoupledtosolutionstoleading-edgetechnicalchallenges, andcannotusefullyberegardedasincrementalchangestoprevioussolutions. This, coupledwith thegeneralavailabilityofextensivetechnicalexpertisewithinsuchcommunities, meansthatanygenericsolutionisveryunlikelytobeappropriate, andthatitisbothreasonableandfeasibletorequirecustomarchivingsolutionsforsuchprojects. Thereisno recipe fordatapreservationonthisscale, andallthatcanbehopedforisastructuredapproachtoacustomsolution. Havingsaid this, noteven themost innovativescienceexperimentsaresocompletely suigeneris thattheywarrantadatapreservationapproachwhichisreimaginedfromscratch. ItisthereforewastefultoignoretheconsiderableintellectualinvestmentsintheOAIS model, thegrowingpenumbraofcommentariesonanddevelopmentsofit, andtheminorindustryofvalidationandauditingeffortsrelatedtoit.

Wearethereforeledtotheconclusionthatthemosteffectiveoverallstrategyforeffectivedatamanagementinthelarge-scaleexperimentalphysicalsciencesisthat fundersshouldsimplyrequirethataprojectdevelopahigh-levelDMPplanasasuitableprofileoftheOAIS specification [4]. Thisprofileshouldbedetailedenoughtorequirenegotiationwiththefunderandwiththeexperiment'scommunity, butcanleavemanyoftheimplementationdetailstothegooden-gineeringjudgementoftheproject'smanagement. WebelievetheLIGO DMPplan [5]canbetakentobeexemplaryinthisregard.

Big-scienceprojectshavethetechnicalskills, themanagementstructures,andthebudgetstotakeonsuchatask, andtodeliveracustomarchivewhichcanbe shown tomeet identifiedgoals. We recommend that funders shouldsupportprojectsincreatingper-projectOAIS profileswhichareappropriatetotheprojectandmeetfunders'strategicprioritiesandresponsibilities.

ThediscussioninSect. 3.5 suggeststhatoneresultofthedevelopmentofanOAIS-based DMP planisthattheresultingplanisexplicitenoughtogenerateusefuldeliverables, andtobenefitfromthegrowinginterestinOAIS ‘validation’.

Wesuggestthefollowingspecificfunderactions.

• ActivelyengagewithprojectstohelpthemdevelopanOAIS profile. Thiswillincludeoverviewliterature, includingtheOAIS specification, tutorialreportssuchas [48], andcommentarysuchas [49], orperhapsspecialised

26


Producer Consumer

Submission Information Packages

Dissemination Information Packages

Archive Information Packages

OAISresult sets

queries

orders

data products

data products

the public scientistsʻthe archiveʼ

observers

Figure 4: Thehighest-levelstructureofanOAIS archive, annotatedwiththecor-respondinglabelsfromconventionalastronomicalpractice(redrawnfrom [4,Fig. 2-4]). Thedisseminationdataproductswilltypicallybethesameasthesubmittedones, butarchivescansometimescreatevalue-addedonesoftheirown.

workshopsifnecessary. Thesearehigh-levelintroductions, ratherthanpro-cedure-basedtick-lists.

• DeveloporsupportexpertiseincriticisingandvalidatingsuchOAIS profiles.Forexample, theCASPAR consortium(seeforexample [50])hasdevelopedstrategies fordetailedvalidationofprojects' claimsabout long-termdatamigration. Similarwork –forexamplevalidatingaproject'sassumptionsabout its DesignatedCommunity –would reassure thewidercommunitythatthearchivedesignislikelytoachieveitsgoalsforthefuture.

Thefirstoftheseisreasonablystraightforward, consistingoflittlemorethangatheringresources. Thesecondisalonger-termprojectwhichmayrequiresomeexpertisetobebuiltupandsupportedatafunder-supportedfacility(suchasRAL,intheUK),orthroughliaisonwiththe DCC.

A corollaryofthismoreactiveengagementisthatfundersmustfinanciallysupportthepreservationworktheyrequire. SeeSect. 3.4.

3 Thepracticalitiesofdatapreservation

3.1 Modellingthearchive

3.1.1 TheOAIS model

WeintroduceherethemainconceptsoftheOAIS model. Fulldetailsarein [4]withausefulintroductoryguidein [48]andsomediscussionintheLSC contextin[5]; theOAIS motivationisfurtherdiscussedinSect. 2.5.

Theterm OAIS standsforan OpenArchivalInformationSystem. Theword‘open’isnotintendedtoimplythatthearchiveddataisfreelyavailable(thoughitmaybe), butinsteadthattheprocessofdefininganddevelopingthesystemisanopenone. TheprincipalconcernofanOAIS istopreservetheusabilityofdigitalartefactsforapragmaticallydefinedlongterm. AnOAIS isnotonlyconcernedwithstoringthelowest-level bits ofadigitalobject(thoughthispartof itsconcern, andisnotatrivialproblem), butwithstoringenough informa-tion about theobject, anddefininganadequately specifiedanddocumentedprocess formigratingthosebitsfromsystemtosystemovertime, thattheinfor-mationorknowledgethosebitsrepresentcanberetrievedfromthematsome

27


WethankDorotheaSalo, oftheUniversityofWisconsinlibrary, for

emphasizingtoustheusefulapplicabilityoftheDCC modeltothecaseofbigsciencedata, andAngusWhyte, forelaboratingthecontrastsbetweentheDCC and

OAIS models.

indeterminatefuturetime. TheOAIS modelcanthereforebeseenasaddressinganadministrativeandmanagerialproblem, ratherthananexclusivelytechnicalone.

TheOAIS specification'sprincipaloutputistheOAIS referencemodel, whichis an explicit (but still rather abstract) set of concepts and interdependencieswhichisbelievedtoexhibitthepropertiesthatthestandardassertsareimpor-tant(Fig. 4 ontheprecedingpage). TheOAIS modelcanbecriticisedforbeingsohigh-levelthat“almostanysystemcapableofstoringandretrievingdatacanmakeaplausiblecasethatitsatisfiestheOAIS conformancerequirements” [49],andthereexistbotheffortstodefinemoredetailedrequirements [49], andeffortstodevisemore stringentandmoreauditableassessmentsofanOAIS'sactualabilitytobeappropriatelyresponsivetotechnologychange [50].

AnOAIS archiveisconceivedasanentitywhichpreservesobjects(digitalorphysical)inthe LongTerm, wherethe‘LongTerm’isdefinedasbeinglongenoughtobesubjecttotechnologicalchange. Thearchiveacceptsobjectsalongwithenough RepresentationInformationtodescribehowthedigitalinformationintheobjectshouldbeinterpretedsoastoextracttheinformationwithinit(forexample, the FITS specification isRepresentation Information for a FITS file).That Informationmayneed furthercontext – forexample, tosay thatafile isanASCII filerequiresonetodefinewhatASCII means –andthecollectionofsuchexplanationsturnsintoa RepresentationNetwork. Thisinformationisallsubmittedtothearchiveintheformofa SIP agreedinsomemoreorlessformalcontractbetweenthearchiveanditsdataproducers.

Oncetheinformationisinthearchive, thelong-termresponsibilityforitspreservationis transferred fromtheprovidertothearchive, whichmustthereforehaveanexplicitplanforhowitintendstodischargethis.

ThearchivedistributesitswarestoConsumersinoneormore DesignatedCommunities, by transforming them, if necessary, into the DIP which corre-sponds to a ‘dataproduct’. Themembers of theDesignatedCommunity arethoseusers, in the future, whomthearchive isdesigned tosupport. Thisde-signrequiresincluding, inthe AIP,RepresentationInformationatalevelwhichallowstheDesignatedCommunity tointerpret thedataproducts withouteverhavingmetoneofthedataProducers, whoareassumedtohavedied, retired, orforgottentheiremailaddresses.

TheOAIS modeloriginatedwithinthespacesciencecommunity, soitcanbemappedtothephysicalsciencedataoftheGW communitywithoutmuchviolence.

3.1.2 TheDCC CurationLifecyclemodel

TheOAIS modelisonthefaceofitalinearone, andsuggeststhatdataiscreated,theningested, thenpreserved, andthenaccessed, inaprocesswhichhasaclearbeginningandend. Thisiscompatiblewiththeobservationthatonepointofarchivingdataistoreuseorrepurposeit, creatingnewarchivabledataproductsinturn, butthislonger-termcycleremainsonlyimplicitinthemodel. TheOAISmodel is thereforeveryusefullyexplicit about thoseaspectsof archivalworkconcernedwithlong-termpreservation, butitsconceptualrepertoireissuchthatadiscussionframedbyitrunstheriskofunderemphasizingtherangeofrolesadatarepositoryhas, orevenofmarginalisingit.

Incontrast, the DCC hasproducedalifecyclemodel [51](Fig. 5 onthenextpage)whichstressesthatdatacreation, management, andreusearepartofacycleinwhichpreservationplanning, forexample, cannaturallyhappenbeforedatacreationaswellasafterit; andinwhichdatacanbeappraised, reappraised, andpossiblydisposedofifitbecomesobsolete. Itthereforemakesexplicitboththeshort-andlong-termcyclesintheflowofactiveresearchdata, anditemphasizestheactiveinvolvementofdatacuratorsinmaintainingthatcycle.

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ACCE

SS, U

SE&

REUS

ETRANSFORM CREATE OR RECEIVE

APPRAISE&

SELECT

STORE

PRESERVATION ACTION

INGEST

CONCEPTUALISE

DISPOSECURATE

PRESERVE

andand

MIGRATEREA

PPRA

ISE

COMMUNITY WATCH & PARTICIPATION

PRESE

RVATION PLANNING

DESCRIPTION

REPRESENTATION INFORMATIO

N

Data(Digital Objects

orDatabases)

Figure 5: TheDCC lifecyclemodel, from[51]

Cyclesofuseandre-usearenottheonlylinksbetweendatasets. Asdis-cussedin [52], onedigitalobjectcanalsoprovidecontextforanother, inava-rietyofways. Tosomeextent this remark rediscovers thenotionof theOAISRepresentationNetwork, andthisinturnpromptsustostressthatalthoughwehavecontrastedOAIS andDCC here, theyarenotincompetition: OAIS iscon-cernedwiththecreationandmanagementofaworkingarchivewithgatekeepersandfirmgoals; theDCC modelisconcernedwiththelocationofthearchiveinthewiderintellectualcontext.

TheDCCmodelisimmediatelycompatiblewiththeobservation, inSect. 3.4below, thatHEP andGW archiveseffectivelyavoidsomepreservationcostsbyseeinglong-termpreservationasonlypartoftheroleofadatarepository. Accept-ingdata, makingitavailableasworkingstorage, transformingitintoimmediatelyusefulforms, orappraising(possiblyregenerable)datasetswhosestoragecostsoutweightheirusefulness, allgivethearchiveafamiliaritywiththedata, andtheresearchersafamiliaritywiththearchive, whichmeansthatthedecisiontoselectcertaindataforlong-termpreservationispotentiallymoreeasilyreached,moreeasilydefendedandmoreeasilyfunded, thanifthearchiveisconceivedasacost-centrebucketboltedonthesideoftheproject. ThisappearstobeborneoutbytheLIGO experience, inwhichthenew DMP planwasdevelopedandsuccessfullyarguedforbythesamepersonnelwhowerelongresponsibleforthedesignandmanagementofthedatamanagementsystemonwhicheveryone'sdailyworkdepends.

3.2 Softwarepreservation

Asdiscussedin, forexample, Sect. 1.6.2, thereisoftenasubstantialamountofimportantinformationencodedinwayswhichareonlyeffectivelydocumentedinsoftware, orsoftwareconfigurationinformation. Thereisthereforeanobviouscaseforpreservingthissoftware(thoughnotethecaveatsofSect. 2.4).

Preservationofasoftwarepipelinerequirespreservingthe pipelinesoftwareitself, apossiblylargecollectionoflibrariesthesoftwaredependson, theoper-

29


http://www.software.ac.uk/

TheUK Starlinkprojectprovidedastronomicalsoftware. Itranfrom

1980to2005, whenitwasrescuedfromoblivionbybeingtakenupby

theUK JointAstronomyCentreHawai‘i. Thecurrentdistribution

includesstill-workingcodefromthe80s. TheNetlibandBLAS librarieshavecomponentswhichdatefrom

the70s.

http://nssdc.gsfc.nasa.gov

http://pds.nasa.gov/http://nssdc.gsfc.nasa.gov/nssdc/

data_retention.htmlhttp://pds.nasa.gov/tools/index.

shtmlWearegratefultoPaulButterworth

ofNASA forhelpfuladvicehere.

http://www.rssd.esa.int/index.php?project=PSA&page=about

atingsystem(OS) itallrunson, andtheconfigurationandstart-upinstructionsforsettingthewholethinginmotion. TheOS mayrequireparticularhardware(CPUsorGPUs), thesoftwaremaybequalifiedforaverysmall rangeofOSsandlibraryversions, anditmaybehardtogatheralloftheconfigurationinfor-mationrequired(thereissomediscussionofhowoneapproachesthisprobleminforexample [26]). Itisnotcertainthatitisnecessary, however: ifthedataproductsarewell-enoughdescribed, thenre-runningtheanalysispipelinemaybeunnecessary, oratleasthaveasufficientlysmallpayofftobenotworththeconsiderableinvestmentrequiredforthesoftwarepreservation. Wefeelthat, ofthetwooptions –preservethesoftware, ordocumentthedataproducts –thelatterwillgenerallybebothcheaperandmorereliableasawayofcarryingtheexperiment'sinformationcontentintothefuture, andthatthistradeoffismoreinfavourofdatapreservationasweconsiderlonger-termpreservation.

This lastpoint, about thechanging tradeoff, emphasizes that the twoop-tionsarenotexclusive: onecanpreservedata and preservesoftware, andtheJISC-fundedSoftwareSustainabilityInstituteprovidesagrowingsetofresourceswhichprovideguidancehere. Howeverthesolutionspresentedgenerallyfocusonactivecuration, inthesenseofpreservingsoftwarethroughcontinuinguseandmaintenance. Thiscanbesuccessful, andistheapproachimplicitin [26],butitseemsbrittleinthefaceofsignificantfundinggaps, andwouldnotdealwellwiththecasewhereasoftwarereleaseisdeliberatelyunused, forexamplebecauseithasbeensuperseded.

3.3 Datamanagementplanning

3.3.1 DMP inspace

Asonemightexpect, bothNASA andESA haveformalised DMP plans.NASA's NationalSpaceScienceDataCenter(NSSDC) hasledNASA'sdata

planningsincethemid-80s. ItwasinitiallytheNSSDCwhichnegotiatedaProjectDMP planwithmissions, butsincethe1990sthishasbecometheresponsibilityoftheNASA PlanetaryDataSystem(PDS).TheNSSDC'sdataretentionpolicydescribeswhatcategoriesofdataproductshouldberetainedindefinitely, andthePDS providesresourcestomissionplannersontheprocessesandtoolsforpreparingdataforpreservation.

ESA'sPlanetaryScienceArchive“providesexpertconsultancytoallofthedataproducersthroughoutthearchivingprocess. Assoonasaninstrumentisselected, PSA beginworkingwith the instrument teamtodefineasetofdataproductsanddatasetstructuresthatwillbesuitableforingestionintothelong-termarchive.”TheESA archiveisbydesigncompatiblewiththePDS.

3.3.2 CurrentandfutureDMP intheLSC

Thecurrent LIGO DMP plan [5], discussesDM planningwithanemphasisonthepreparationsfortheeventualpublicdatarelease.

TheLIGO DMP planproposesatwo-phasedatareleasescheme, tocomeintoplaywhen aLIGO iscommissioned; thiswaspreparedattherequestoftheNSF,developedduring2010–11, andwillbereviewedyearly.

TheplandocumentsthewayinwhichtheconsortiumwillmakeLIGO dataopentothebroaderresearchcommunity, ratherthan(asatpresent)onlythosewhoaremembersof theLSC.Thisdocumentdescribes theplans for thedatareleaseanditsproprietaryperiods, andoutlinesthedesign, function, scopeandestimatedcosts oftheeventualLIGO archive, asaninstanceofanOAIS model.This isahigh-levelplan, withmuchof thedetailed implementationplanningdelegatedtopartnerinstitutionsinthemediumterm.

30

http://www.software.ac.uk/


http://pds.nasa.gov/

http://nssdc.gsfc.nasa.gov/nssdc/data_retention.html

http://nssdc.gsfc.nasa.gov/nssdc/data_retention.html

http://pds.nasa.gov/tools/index.shtml

http://pds.nasa.gov/tools/index.shtml




Inthefirstphase, dataisreleasedmuchasitisatpresent: validateddatawillbereleasedwhenitisassociatedwithdetections, orwhenitisrelatedtopapersannouncing non-detections(forexample, associatedwithanotherastronomicaleventwhichmightbeexpectedorhopedtoproducedetectableGWs). Inthesecondphase –afterdetectionshavebecomeroutine, andtheLIGO equipmentisactingasanobservatoryratherthanaphysicsexperiment –thedatawillberoutinelyreleasedinfull: “theentirebodyofgravitationalwavedata, correctedforinstrumentalidiosyncrasiesandenvironmentalperturbations, willbereleasedtothebroaderresearchcommunity. Inaddition, LIGO willbegintoreleasenear-real-timealertstointerestedobservatoriesassoonasLIGO may havedetectedasignal.”ThissecondphasewillbeginafterLIGO hasprobedagivenvolumeofspace-time(see[5, ref7]), or after3.5yearshaveelapsedsincetheformalLIGOcommissioning, whicheverisearlier. Alternatively, LIGOmayelecttostartphasetwosooner, ifthedetectionrateishigherthanexpected.

Inphasetwo, thedatawillhavea24-monthproprietaryperiod.TheDMP plandescribesthree(OAIS) DesignatedCommunities. Quoting

from [5, §1.5], thecommunitiesareasfollows.

• LSC scientists: whoareassumedtounderstand, orberesponsiblefor, allthecomplexdetailsoftheLIGO datastream.

• Externalscientists: whoareexpectedtounderstandgeneralconcepts, suchasspace-timecoordinates, Fouriertransformsandtime-frequencyplots, andhaveknowledgeofprogrammingandscientificdataanalysis. Manyofthesewillbeastronomers, butalsoinclude, forexample, thoseinterestedinLIGO'senvironmentalmonitoringdata.

• Generalpublic: thearchivetargetedtothegeneralpublic, willrequiremin-imalscienceknowledgeandlittlemorecomputationalexpertisethanhowtouseawebbrowser. WewillalsorecommendorbuildtoolstoreadLIGOdatafilesintootherapplications.

TheLIGO DMP planis, webelieve, agoodexampleofaplanforaprojectofLIGO'ssize: itisspecificwherenecessary, itwasnegotiatedwiththeproject'sfunder(NSF) sothatitachievedtheirgoals, anditwentthroughenoughiterationswiththebroaderLIGO community(theagreedversionin[5]isversion 14)thatitsauthorscouldbeconfidentithadtheirapproval, andthatthecommunitywascomfortablewithwhattheDMP planwasproposing. ThedocumenthasastrongfocusontheLIGO datareleasecriteria, sincethiswasthemostimmediatecon-cernofboththefunderandtheproject, butitsystematicallylaysoutahigh-levelframeworkforfuturedatapreservation, guidedbytheOAIS functionalmodel.

3.4 Datapreservationcosts

Thereisagooddealofdetailedinformation, andsomemodelling, ofthecostsofdigitalpreservation. TheKRDS2study[44, §§6&7]includesdetailedcostingsfromanumberofrunningdigitalpreservationprojects, insomecasesdowntothelevelofcostingsspreadsheets. TheLIFE3 projecthasalsodevelopedpredictivecostingstools [53], andthePLANETS project(http://www.planets-project.eu/)hasgeneratedabroadrangeofmaterialsonpreservationplanning, includingcostingstudies.

Although there is a broad rangeof preservationprojects surveyed in theKRDS report, therearenumerouscommonfeatures. Staffcostsdominatehard-warecosts, andscaleonlyveryweaklywitharchivesize. Thestudyalsonotesthatacquisitionandingestcostsareasubstantial fraction(70–80%)ofoverallstaff costs, but also scaleveryweaklywitharchive size. Theseare relativelysmallarchives, generallybelowafew TB insize, whereingestisasignificant

31

http://www.planets-project.eu/


WearemostgratefultoFernandoComerón, ofESO,forsharingthese

figures.

http://pds.nasa.gov/tools/cost-analysis-tool.shtml

componentoftheworkload. Inthisreportweareinterestedinarchivesthreeorfourordersofmagnitudelargerthanthiswhere(asdiscussedbelow)ingestmaybecheaper, butinbroadterms, itappearsstilltobetruethatstaffcostsdominatehardwarecostsatlargerscales, andscaleonlyweaklywitharchivesize.

Parenthetically, noticethattheabovediscussionpromptsthequestion‘whatisthesizeofanarchive?’Thenumberofbytesitconsumesisanobviousandreadilyavailablemeasure, butmaynotbeparticularlymeaningfulinthiscontext.Thenumberof items (suchas interview transcripts, imagesordatabase rows)maybeabettermeasure, andstillobjectivelyidentifiable, archivebyarchive. Ifthereweresomemeasureofabstractinformationcontent, wespeculatethatthisiswhatwouldscalemoststraightforwardlywiththeeffortrequiredforqualitycontrolandmetadatacuration, andhencewithstaffeffort. Wehesitatetoaskwhatsuchameasuremightbe, incasetheansweris‘citationanalysis’.

Thelackofscalingwithsize, evenwhenanarchiveprogressivelygrowsinsize, seems tosuggest that it isanarchive's initial size (in thesenseof small,mediumorlarge, forthetime)thatlargelygovernsthecosts.

Weweregivenaccesstoconfidentialfiguresforthedevelopmentandop-erationsofamid-to-largesizeastronomyarchive (oforder 10 TB ofrelationaldataand 100 TB offlatfiledata), developedbyanexperiencedarchivesite. Thearchivesoftwareandsystemdevelopmentcost25–30staff-yearsofeffort: thebulkofthiswasforthecoredatabasesystem, butbetweenaquarterandathirdwasforsoftwaretosupportingestandthegenerationofdataproducts. Theor-ganisationbudgetsaround3 FTEsforoperationofthisarchive, whichincludesingest, qualitycontrolandhelpdesksupport(thisisanestimatedfractionofanoperationsteamcoveringseveralarchivesatthesamesite, sotheremaybesomeeconomiesofscale). Aboutaquarteroftheannualoperatingbudgetisspentonhardware.

The EuropeanSouthernObservatory(ESO) dataarchivemanagesdatafrommultipleESO facilities; itsharesspacewiththestill-developingALMA archive,butthefiguresbelowdonotincludeALMA.Thearchiveisbasedonspinningdisksbackedbyatapelibrary(forfurtherdetails, see [54]). Itcurrentlyholds190 TB, increasingataround 7 TBmonth−1. Thehardwarecostsaveragearound330 k€ yr−1, whichincludeshardwarereplacementanddatamigration, andwhichhasremainedflat forsomeyears, despite theslowlyincreasingdatavolumes.Runningcostsamountto 55 k€ yr−1 (somesmallersystemsaccountforpartofthis), andlicences, networksandotherconsumablesaccountforabout 30 k€ yr−1.Manpowercostscometo4 FTEsofESO staffplusaround 270 k€ yr−1 ofout-sourced staff. Neitherhardwarenor softwarecostsappear to scalewithdatavolume, withsomecostelementsevendroppingasthearchivemovestocom-pletelyon-linedatadistribution.

Thereissomediscussionofthe CDS fundingmodelinSect. 1.4.1.The NASA PDS hasdevelopedaparameterizedmodelforhelpingproposers

estimate the costs involved in preparing data for archiving in the PDS;mostrelevantly for the abovediscussion it includes a scalingwithdata volumeof1 + 1.5 log10(volume/MB) (thatis, amultiplierwhichincreasesby1.5foreachorderofmagnitudeincreaseindatavolume).

AsnotedinSect. 1.5, theHEP communityisnowconstructingmoredetailedplansfordatapreservation, andtheassociatedcosts. Reference [26]estimatesthataformallong-termarchive(alevel-3or-4archive, inthetermsofthatpaper)wouldcost2–3FTEsfor2–3yearsaftertheendoftheexperiment, followedby0.5–1.0FTE/year/experimentspentonthearchive'spreservation. Theycomparethistothe100sofFTEsspentonfortherunningoftheexperiment, andonthisbasisclaimanarchivalstaff investmentof1%of thepeakstaff investment, toobtaina5–10%increaseinoutput(thelatterfigureisbasedontheirestimatethataround5–10%ofthepapersresultingfromanexperimentappearintheyearsimmediatelyaftertheexperimentfinishes; sincethislatterfigureisderivedonthe

32




currentmodel, whichachievesthiswithoutanyformalpreservationmechanisms,thisestimateofthereturnoninvestmentinarchivesmaybeoptimistic).

Itisworthnotingthatinastronomical, HEP andGW contexts, archiveingestisgenerallytightlyintegratedwiththesystemforday-to-daydatamanagement, inthesensethatdatagoesdirectlytothearchiveonacquisitionandisretrievedfromthatarchivebyresearchers, aspartofnormaloperations. Ontheothersideofthearchive, projectswillgenerateanddisseminatedataproducts –whichlookverymuchlikeOAIS DIPs –aspartoftheirinteractionwithexternalcollaborators,withoutregardingtheseasspecificallyarchivalobjects. ThusthesubmissionsintothearchivemayconsistofbothrawdataandthingswhichlookverymuchlikeDIPs, andtheobjectsdisseminatedwillincludeeitherorbothveryrawandhighlyprocesseddata. The long-term planningrepresentedintheLIGO DMPplan [5], forexample, is therefore lessconcernedwith settingupanarchive,thanwiththeadjustmentsandformalizationsrequiredtomakeanexistingdata-managementsystemrobustforthearchivallongterm, andmoreaccessibletoawiderconstituency. Whatthismeans, inturn, isthatsomefractionoftheOAISingestanddisseminationcosts(associatedwithqualitycontrolandmetadata, forexample)willbecoveredbynormaloperations, withtheresultthatthe marginalcostsoftheadditionalactivity, namelylong-termarchivalingestanddissemina-tion, areprobablybothratherlowandtypicallybornebyinfrastructurebudgetsratherthanrequiringextraeffortfromresearchers. Thisiscorroboratedbyourin-formantsabove, whogenerallyregardarchivecostsascomingunderadifferentheadingfrom‘dataprocessingcosts’. ThepointhereisnotthattheOAIS modeldoesnotfitwell –itfitsverywellindeed –northatingestanddisseminationdonothavecosts, butthatiftheassociatedactivitiescanbecontrivedtooverlapwithnormaloperations, thenthecostsdirectlyassociatedwiththearchivemaybesignificantlydecreased. Thisistheintuitionbehindtherecentdevelopmentsin‘archive-ready’or‘preservation-awarestorage’(cf[43]andSect. 3.1.2), andconfirmsthatitisaviableandeffectiveapproach.

Asafinalpoint, wenotethatbig-scienceprojectsareinevitablyalsolarge-scaleengineeringprojects, sothat theconsortiaandtheir fundersarebroadlyfamiliarwiththeprocedures, uncertaintiesandmanagementofcostestimates,sothatthecostingandmanagementofdatapreservationcanbenaturallybuiltintotherelationshipbetweenfundersandfunded, ifthefunderssorequireit.

Asisshownbythevaguenessofsomeoftheremarksabove(despitesome-timesveryspecificnumbers), thereseemslittleinthewayofaconsensusmodelforthecostingofthelong-termpreservationoflarge-scaledata. TherewillsurelybedetailedcostingsforthemanagementofPB-scaledataforcommercialorgani-sations, butthesearenotlikelytobeusefulforourpurposes, sincetheyaremoreconcernedwithimmediatebusinesscontinuitythanmulti-decadearchives, areservingdifferenttechnicalcommunities, andarelikelytobeextremelyconfiden-tial.

Wethereforerecommendthat STFC shoulddevelopacostingsmodelforthepublicationandpreservationofdata, whichismatchedtothedatachallengesofthebig-sciencecommunity. Weexpectthatthiscanbuildonthedomain-agnosticworkalreadydoneinthisareabyJISC,andonthedetailedworkdoneoncloselyrelatedproblemsby NASA'scost-estimationcommunity [56].

3.5 TheGW communityandtheAIDA toolkit

TheAIDA Self-AssessmentToolkit [57] isa(JISC funded)setofqualitativebench-marks fordiscussingathowdevelopedan institution'sarchive is. It leadsanarchivemanagerthroughasetofafewdozenelements, invitingthemtogradetheirarchivefrom1(poor)to5(internationalexemplar). Thegoalisnottopro-duceapass/fail score, but instead tohelparchivemanagersunderstand theircurrentandfuturerequirements, andto“enableaninstitutiontodecidewhether

ThisisconsistentwiththeERIMproject'sconclusionsthat“ideallyinformationmanagementinterventionsshouldresultinazeronetresourceincrease” [55, p.8]. Inthiscasethereisnoextraresourcerequiredfromtheresearchers,thoughtheremightbeaneedforextraresourceunderaninfrastructureheading.

Recommendation4

TheAIDA documentlinksthesefivestages, ratheralarmingly, toafive-stepprogrammedevelopedatCornell, whichstartswithacknowledgingthatyouhaveaproblem, andgoes, viainstitutionalisation, to“embracing[…]dependencies”, notingthat“youcan'tdoitalone”. Clearly,data-managementplanningishabit-forming.

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specificactionsneedtobetakeninregardtoparticularassets, orwhenandhowitisdesirabletoimproveonitscurrentcapabilities”. TheAIDA authorsacknowl-edgethattheassessmentissimplisticandsubjective, butstressthat“AIDA aimstoallowyoutoevaluateyourinstitutionagainstarecognisedcapabilityscale, andthensuggestsappropriateactionsbasedonthatevaluation”. TheAIDA goalistomodeltheprogressofanarchivefromtheacknowledgementthatanarchiveisdesirable, throughtotheexemplaryexternalisationofthearchiveasaresource.

InAppx. B,welistourestimatesofthescoresforLSC datamanagement. WehopetheseassessmentsareofspecificusetotheGW community, butbelievethatthediscussioningeneralmaybeofusetoother, similarlystructured, bigsciencecommunities.

ThescoresforthecurrentLSC clusterinthemiddle, aroundthree(whichcorrespondsto‘consolidate’intheCornellmodel). Thisisanimpressivescoreforaprojectwhichis, fromonepointofview, doingonlywhatisregardedasnormalforawell-runlarge-scalephysicsexperiment. Thehigherscoresaregenerallyassociatedwiththeformalityandauditabilityofthelong-termplans, ratherthananyqualitativelydifferentpractice, andwebelievethatthesescoreswillnaturallydriftupwardsasaresultofthedevelopmentofanexplicitDMP plan, structuredusingtheOAIS conceptset, incollaborationwithasuitablycriticalfunder.

Thetoolkitisbrokenintoorganisational, technologyandresources(gener-allyfunding)‘legs’.

The ‘organisational leg’ is concernedwith the high-level support for thearchive. Totheextentthatitismeaningful, theaverageforthesescoresisabovethree (which isgood). The lowerscoresaregenerallyassociatedwith the in-formalityofthecurrentarchive(comparedtoaservice-orientedcommercialor-ganisation)rather thananymoreconcrete inadequacy: thedata isbackedupandreasonablyfindable, thoughthisreflectsculturalnormswithinthephysicalsciencesratherthansomethingaparticulararchivingplancantakecreditfor.

The‘technologyleg’isconcernedwiththehardwareandpersonnelsupportfordatamanagement. Aswiththeorganisationalleg, theGW communityscoreshighlyherewithoutreallytrying, simplybecausethecommunityhaslongexperi-enceofmanaging andsharing largevolumesofdata. Thelowerscoresareagainassociatedwiththecurrentinformalityofoperations(fromthepointofviewofanarchiveasopposedtoaworkingdata-managementinfrastructure), andthesewillnaturallyrisewhentheLSC's DMP planisimplementedandreviewed.

Thescoresinthe‘resourcesleg’aretheleastwell-justified. TheLSC gener-allyscoreswell, inthesensethatwecanbeconfidentthattherewillberesourcestosupportanarchiveeffort –it'sseenasahigh-importanceactivity –eventhoughtherearefewresourcescurrentlyexplicitlyearmarkedforthis. Thissectionmaythereforebeusefulforsuggestingwhatbudgetlinesshouldeventuallyexist.

4 Conclusionsandrecommendations

Inthisreport, wehavedescribedsomeofthewaysinwhich‘bigscience’man-agesitsdata, aspartofabroaderdataculturewhichischaracterisedbylargecol-laborations, andwhichhasdecadesofexperienceinagreeinghow, andwhen,andwhennot, tosharedata.

Wecansaywithsomeconfidencethatthebigsciencedataculturemanagesitsdatawell(andthisseemstobecorroboratedbytheAIDA assessmentdiscussedinSect. 3.5), butwearenotsuggestingthatotherdisciplinescouldorshouldsimplycopythisculture, sincetherearevariousreasons(cf, Sect. 1.3)whythiscultureisparticularlynaturalinsomeareas.

Therearehoweversomepracticeswhichwedobelievearestraightforwardlyportabletootherdisciplines. AswediscussinSect. 1.11, thenotionsof dataproducts and proprietaryperiods verynaturallyconcretizeotherwisediffusear-

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gumentsaboutdatamanagementandsharing, transformingthemfrom‘whether’and‘why’to‘which’and‘howlong’. Aswell, webelievethatembeddingdatamanagementintheday-to-daypracticeofresearcherslowerscostsinboththeshortterm(researcherscaneasilyre-findtheirowndata, andinterpretothers')andthelongterm(sincepreservationbecomesatechnicalproblemofconserv-inganin-userepository). WediscussthecostingofdatamanagementatslightlygreaterlengthinSect. 3.4.

Werepeatourexplicitrecommendationsbelow.

1. Datamanagersshouldconsideradoptingthelanguageofdataproductsandexplicitproprietaryperiodswhendesigninganddocumenting theirhold-ings (Sect. 1.11, p21).

2. Fundersshouldsimplyrequirethataprojectdevelopahigh-levelDMP planasasuitableprofileoftheOAIS specification [4] (Sect. 2.6, p26).

3. Fundersshouldsupportprojectsincreatingper-projectOAIS profileswhichareappropriatetotheprojectandmeetfunders'strategicprioritiesandre-sponsibilities (Sect. 2.6, p26).

4. STFC shoulddevelopacostingsmodelforthepublicationandpreservationofdata, whichismatchedtothedatachallengesofthebig-sciencecommu-nity (Sect. 3.4, p33).

Acknowledgements

ThisprojectwasfundedbyJISC,aspartofthe‘ManagingResearchData’pro-gramme. Wearemostgratefultothenumerouspeoplewhohavecommentedonvariousdraftsof this report, orprovideduswith informationor resources.Inparticular, wethankStuartAnderson(LIGO),PaulButterworth(NASA),HarryCollins(Cardiff), FernandoComerón(ESO),JoyDavidson(DCC),FrançoiseGen-ova(CDS),MagdalenaGetler(DCC),SimonHodson(JISC),SarahJones(DCC),DorotheaSalo(Wisconsin), AngusWhyte(DCC),andRoyWilliams(LIGO).

A Casestudy

WehaveproducedadetaileddiscussionofthestructureoftheLIGO workingdatamanagementsystem, asaseparatedocument [29]. Thisdocumentiscur-rentlyavailableonlywithinLIGO:thoseobservationswhichhavenotbeenin-corporated into thispresent reportareprobably toodetailed tobeofgeneralinterest. Wehope, however, thatthecase-studywillbeofsomeuseinternallytototheLSC.

B AIDA assessment

TheAIDA self-assessmenttoolkit [57] isa JISC-fundedsetofqualitativebench-marksforassessinghowdevelopedaninstitution'sarchiveis. SeeSect. 3.5 fordiscussion.

Thelabelsinthetablebelowaresometimesalittlecryptic; refertothefulltoolkitforusefulelaborations.

Theanswersbelowgenerallyrefertothe early2011 stateoftheLSC archivearrangements, on thegrounds thatconcreteanswers toavariantquestionarepreferabletospeculativeanswerstoafutureone. Theseareprobablyareason-ableindicationofthelikelystatusofaforthcomingformalarchive, butinafewcase, asnoted, wecangivenomeaningfulanswer.

Inthescoresbelow, level 1is‘poor’, andlevel 5is‘internationalexamplar’.

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Organisationalleg

1: institution-widemissionstatements(5) TheLIGO projecthaspreparedafor-malDMP,atfunderrequest

2: institutionalpoliciesforassetmanagement(3) LIGO haspreparedaformalDMP,andisaddressingpoliticalandculturalreservations, awaitingfundingandimplementation

3: reviewmechanismsatInstitutionallevel(4) Aswell as theDMP, there al-readyexistwell-understoodcollaboration-widereviewprocedures, andthesewillbeusedtoreviewtheplanonanannualbasis

4: institutionalcapabilityforsharingassets(3) Currentstorageis, ofnecessity,distributed; thecollaborationmanagesthisinformallybuteffectively, how-everthisisgenerallyworkingstorage, andnotregardedasarchivalstorage

5: institutionallevelofcontingencyplanning(3) Thereisnoformalcentralisedassetmanagement. Continuityisregardedasatechnicalmatterwhichcanreasonablybelefttotheprofessionalgoodpracticeofthesitesmanagingthedistributedstorage. Asbefore, thisiscurrentlyregardedasworkingratherthanarchivalstorage.

6: institutionalcapabilityforaudit(3) Extensivelogsexist, butarenotcentralisednorinanystandardformat; files, oncecreated, arenotexpectedtobemod-ified, thoughthereisnowaytoverifythatthisistrueinfact

7: institutionalmonitoringmechanisms(4.5) Alldataandprocessesareopentotheentirecollaboration, andmostprocessesarewidelydiscussed; thecollaborationisitsownuser-base. Thereare(bydesign)noexternalusersofthedata, noryetanyexternalreviewofthemechanisms.

8: extentofinstitutionalconformancetometadatamanagement(2to4) Meta-dataisdevisedinasomewhat adhoc waybyindividualinstrumentsorsoft-wareelements(stage2), butthisisalsoaddedandmanagedthoroughly, andinaccordancewithwhatisregardedasexperimentalgoodpractice(stage4)

9: extentofinstitutionalcontracts(3) Notapplicable tocurrentworkingstor-age

10: institutionalunderstandingofIPR (5) FormalMoUsbetweenpartnersregard-ingaccesstodata, andclearguidancefromfundersregardingtheeventualreleaseofthedata

11: institutionaldisasterplanning(2) Aswithassetcontinuity, thisiscurrentlyregardedasatechnicalmatterforstoragemanagers

Technologicalleg

1: institutionalinfrastructure(5) Thecollaborationhasconsiderabletechnicalresource, and interoperateswell. Planning is informalbuteffective. Thesophisticateduser-baseiscomfortablewiththisinformality, butthiscouldinprinciplebecomealiabilitywhentheresourcemanagementmovesfromadevelopmenttoaservicemodel.

2: appropriatenessofinstitutionaltechnologies(4) Thereisplentyofappropri-atetechnology, thoughtheplanforthearchivalmanagementofassetsisnotyetdetailed

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3: integrityofinstitutionalbackupandstorage(3) Importantdataisbackedup(possiblybymirroring), aspartofnormaloperations

4: institutionalprocesses(2) Uncertain: what there iswillbedoneaspartofnormaloperations

5: institutionalunderstandingofobsolescence(3.5) Highgeneralawareness, andoccasionaldiscussion, butatpresentlittleformalplanning

6: institutionalcapability(4) Changestoprocessesarewidelyandfranklydis-cussed, anddocumentedasinternalpublications; changeismanagedeffec-tively, butrelativelyinformally

7: institutionalcapabilityforsecurity(3) Thereisahighlevelofawarenessoftheneedtokeepthedataproprietary, butgiventhescientificcontext, therearenolikelyattackscenariosassuch; theproblemwill largelyevaporateoncethedataisfinallyreleasedpublicly

8: institutionalsecuritymechanisms(3.5) Noformalthreatanalyses, butthese-curityisprobablyappropriatetothelevelofthreat; day-to-dayattacks(ienotspecificallytargetedatthisdata)aretheresponsibilityofdistributedstorageandcomputingmanagers

9: institutionaldisasterplanandcapacityforbusinessrecovery(3) Notapplica-bletothecurrentexperimentalphase

10: institutionalcapacitytocreatemetadata(4) Almostallmetadataisaddedautomatically(compareorganisational.08)

11: effectivenessofanInstitution-widerepository(2) LIGO haspreparedafor-malDMP

Resourcesleg

1: institutionalbusinessplanning(2) LIGO ispreparingaformalDMP

2: institutionalcapacityforreview(4) DMP tobereviewedannually; projectasawholehascloserelationshipswithfundersandstakeholders

3: institutionalcapabilityforresourceallocation(4) Resourceplanning isco-ordinatedataseniorlevel

4: institutionalcapabilityforriskmanagement(2) Generalawarenessatpresent,butthisshouldbecomeclearerinfutureDMP iterations

5: institutionalbusinesstransparency(4.5) Dependingontheprecisemeaningintended, thiscouldbe4or5. Thereissubstantialauditingfromcollabora-tionfunders

6: institutionalcapacityforsustainablefunding(3.5) Good relationships withfundersmeanthatfundingisprobablypredictableonfive-toten-yeartime-scales, butunpredictableinthelongerterm. Howeverthemainfunder(NSF)hasexpressedastrategiccommitmenttolong-termdatapreservation.

7: institutionalstaffmanagement(3) Notapplicabletothecurrentexperimen-talphase

8: institutionalmanagementofstaffnumbers(3) Notapplicabletothecurrentexperimentalphase

9: institutionalcommitmenttostaffdevelopment(3) Notapplicabletothecur-rentexperimentalphase

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Aboutthisdocument

LIGO-P1000188-v10, 2011June29 First public version, available at https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p1000188

v1.1, 2012July14 Minorrevisions, someaddedmaterial, andtyposandminorerrorscorrected. Thereareacoupleofadditionalsections, butnochangestosectionorfigurenumbers. Thepaginationwillhavechangedinplaces.

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[52] Christopher E Lee. Takingcontextseriously: A frameworkforcontextualinformationindigitalcollections. TechnicalReportSILS TechnicalReport2007-04, UniversityofNorthCarolina, October2007. Availablefrom:http://sils.unc.edu/sites/default/files/general/research/TR_2007_04.pdf.

[53] BrianHole, Li Lin, PatrickMcCann, andPaulWheatley. LIFE3: Apredictivecostingtoolfordigitalcollections. In iPres, September2010.SubmittedtoiPres. Availablefrom:http://www.life.ac.uk/3/docs/Ipres2010_life3_submitted.pdf.

[54] PaulEglitisandDieterSuchar. Historicallessons, inter-disciplinarycomparison, andtheirapplicationtothefutureevolutionoftheESOarchivefacilityandarchiveservices. In EnsuringLong-TermPreservationandAddingValuetoScientificandTechnicalData.EuropeanSpaceAgency, December2009. Availablefrom: http://www.sciops.esa.int/SYS/CONFERENCE/include/pv2009/papers/34_Eglitis_ESO_ARCHIVE.pdf.

[55] MansurDarlington, AlexBall, TomHoward, SteveCulley, andChrisMcMahon. RAID associativetoolrequirementsspecification(version1.0).TechnicalReportERIM Projectdocumenterim6rep101111mjd10,UniversityofBath, 2011. Toappear. Availablefrom:http://opus.bath.ac.uk/22811.

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[57] UniversityofLondonComputerCentre. TheAIDA self-assessmenttoolkitmarkII,February2009. Availablefrom:http://aida.jiscinvolve.org/toolkit.

42

http://www.sciencemag.org/cgi/reprint/303/5665/1777.pdf

http://dx.doi.org/10.1126/science.1095958

http://www.dcc.ac.uk/docs/publications/reports/Data_Sharing_Report.pdf

http://www.nsf.gov/publications/pub_summ.jsp?ods_key=gc1010

http://www.dpconline.org/docs/lavoie_OAIS.pdf

http://www.dlib.org/dlib/november05/rosenthal/11rosenthal.html

http://www.casparpreserves.eu/Members/cclrc/Deliverables/caspar-validation-evaluation-report/at_download/file

http://www.casparpreserves.eu/Members/cclrc/Deliverables/caspar-validation-evaluation-report/at_download/file

http://www.dcc.ac.uk/resources/curation-lifecycle-model

http://sils.unc.edu/sites/default/files/general/research/TR_2007_04.pdf

http://www.life.ac.uk/3/docs/Ipres2010_life3_submitted.pdf

http://www.sciops.esa.int/SYS/CONFERENCE/include/pv2009/papers/34_Eglitis_ESO_ARCHIVE.pdf

http://www.sciops.esa.int/SYS/CONFERENCE/include/pv2009/papers/34_Eglitis_ESO_ARCHIVE.pdf

http://opus.bath.ac.uk/22811

http://www.nasa.gov/offices/pae/organization/cost_analysis_division.html

http://aida.jiscinvolve.org/toolkit


Glossary

Termsmarked‘OAIS’arecopiedfromtheOAIS specification[4, §1.7.2].

ADS AstrophysicalDataService: abibliographicarchiveforastronomy, basedattheHarvard-SmithsonianCenterforAstrophysics; ADS preservesfull-textcopiesofjournalarticles, bothincollaborationwithpublishers, andthroughadigitizationprocess, andmaintainsawidely-usedbibliographicID system(http://ads.harvard.edu). 10, 11, 19

AIP Archival InformationPackage: An InformationPackage, consistingof theContentInformationandtheassociatedPreservationDescriptionInforma-tion, whichispreservedwithinanOAIS (OAIS).20, 23, 28

aLIGO AdvancedLIGO:Thesuccessorproject toLIGO,duetostart in2015.14, 15, 24, 30

arXiv A electronicpreprintservice, see http://arxiv.org. ThearXivstartedintheearly90s, basedonFTP andemail. Itinitiallyservicedparticlephysicsandastronomy, buthasexpandedtocoverotherareasofphysics, mathematics,andsomeareasofcomputingscience. 10

ATLAS OneofthefourdetectorsattheLHC,andoneofthetwolargeones. 6,14

bigscience A classofscienceprojectscharacterisedbybeinginternational, highlycollaborativeandexpensivelyfunded(seeSect. 1.1 formorediscussion). 4,5, 34

catalogue Intheastronomicalcontext, acatalogueisatableofpositionsandotherinformationforstarsorotherotherastronomicalobjects. 9--11

CCSDS ConsultativeCommitteeforSpaceDataSystems: authorsof theOAISreferencemodel, see http://www.ccsds.org. 25

CDS StrasbourgDataCentre: (see http://cdsweb.u-strasbg.fr/ andSect. 1.4.1).11, 32

CMS CompactMuonSolenoid: OneofthefourdetectorsattheLHC,andoneofthetwolargeones. 14

ContentInformation Thesetofinformationthatistheoriginaltargetofpreser-vationbytheOAIS (OAIS).17, 19

DataObject EitheraPhysicalObjectoraDigitalObject(OAIS) (thatis, the`DataObject'isthesequenceofbits, orthephysicalobjectwhichis thedata inthemostprimitivesense). 24

dataproducts Formaldataoutputsfromanobservatory, instrumentorprocess(seeSect. 1.4). 10

datasharing Theformalisedpracticeofmakingsciencedatapubliclyavailable.22

DCC DigitalCurationCentre: http://www.dcc.ac.uk (nottobeconfusedwiththeLSC DocumentControlCenter). 4, 5, 27, 28

DesignatedCommunity AnidentifiedgroupofpotentialConsumerswhoshouldbeabletounderstandaparticularsetofinformation(OAIS).11, 17, 24, 25,27, 28, 31

43

http://ads.harvard.edu

http://arxiv.org


http://cdsweb.u-strasbg.fr/

http://www.dcc.ac.uk


DIP DisseminationInformationPackage: TheInformationPackage, derivedfromoneormoreAIPs, receivedbytheConsumerinresponsetoarequesttotheOAIS (OAIS).20, 28, 33

DMP DataManagementandPreservation. 12, 16, 26, 29--31, 34

ESA EuropeanSpaceAgency: http://www.esa.int. 6, 11, 12, 30

ESO EuropeanSouthernObservatory: A pan-europeanagencyrunningasetofsouthern-hemispheretelescopes http://www.eso.org. 32

ESRC EconomicandSocialResearchCouncil: theprincipalsocialsciencefun-derintheUK,see http://www.esrc.ac.uk. 17

FITS FlexibleImageTransportSystem: thestandardfileformatinastronomy, seehttp://fits.gsfc.nasa.gov. 10

GEO A German-Britishconsortium, responsiblefortheGEO600interferometer,fundedjointlybySTFC andtheGermangovernment. 14

GEO600 TheGEO observatorylocatednearHannoverinGermany. 14

GW GravitationalWave. 4, 5, 8, 12, 14

HEP HighEnergyPhysics. 8, 12, 13

HERA A particleacceleratorattheGermanDESY facility. 13

InformationPackage TheContentInformationandassociatedPreservationDe-scriptionInformationwhichisneededtoaidinthepreservationoftheCon-tentInformation. TheInformationPackagehasassociatedPackagingInfor-mationusedtodelimitandidentifytheContentInformationandPreservationDescriptionInformation(OAIS).20, 25

IVOA InternationalVirtualObservatoryAlliance: theconsortiumwhichdefinesVO standards. 12, 19

JISC JointInformationSystemsCommittee: TheorganisationresponsibleforthemaintenanceandeffectiveexploitationoftheacademiccomputingnetworkintheUK,andthefundersofthispresentreport. 4, 5, 33, 35

KRDS KeepingResearchDataSafe: JISC projectdevelopinganddocumentingdatapreservationtoolsandstudies; see http://www.beagrie.com/krds.php and[44]. 21

LHC TheLargeHadronCollideratCERN:theacceleratoristhehostfortwolargegeneralpurposedetectors(ATLAS andCMS) andtwosmallerones(ALICEandLHCb). 6, 12, 13

LIGO LaserInterferometerGravitational-waveObservatory: thehardware, com-prisingLIGO LabandGEO (see http://ligo.org andSect. 1.6.1). 5, 6, 12,14, 16, 17, 30

LIGO Lab TheCaltech/MIT consortium, fundedbyNSF todesignandruntheLIGO interferometersintheUS,see http://www.ligo.caltech.edu. 14

LongTerm A periodoftimelongenoughfortheretobeconcernabouttheim-pactsofchangingtechnologies, includingsupportfornewmediaanddataformats, andofachangingusercommunity, ontheinformationbeingheldinarepository. Thisperiodextendsintotheindefinitefuture(OAIS).8, 28

44

http://www.esa.int

http://www.eso.org

http://www.esrc.ac.uk

http://fits.gsfc.nasa.gov


http://ligo.org

http://www.ligo.caltech.edu


LSC LIGO ScientificCollaboration: ThenetworkofresearchgroupscontributingefforttotheLIGO experimentanddataanalysis, see http://ligo.org. 4, 5,14, 16

LVC A data-sharingagreementbetweentheLSC andtheVirgoCollaboration(seeSect. 1.6.1). 5, 14

MOU MemorandumofUnderstanding: therelationshipsbetweenthevariousparticipatingentitiesandtheLSC isarticulatedthroughaseriesofannuallyreviewedMOUs. 14

MRD ManagingResearchData: A fundingprogrammewithintheJISC e-Researchtheme, see http://www.jisc.ac.uk/whatwedo/programmes/mrd. 4, 23

NASA NationalAeronauticsandSpaceAdministration: TheUS spaceagencyhttp://www.nasa.gov. 6, 9, 30, 32, 33

NSF NationalScienceFoundation: theprincipal(non-defence)sciencefunderintheUSA.4, 22, 30

NSSDC NationalSpaceScienceDataCenter: thepermanentarchiveforNASAspacesciencemissiondata http://nssdc.gsfc.nasa.gov. 30

PDS PlanetaryDataSystem: TheNASA dataarchiveandstandardset http://pds.nasa.gov/. 30, 32

pipeline A software system (or sometimesa software-hardwarehybrid)whichtransforms rawdata intomoreormore levelsofdataproduct. Thedatareductionpipelines, whichmustbeabletokeepupwiththerateatwhichdataisacquired, andwhichareassembledfromamixtureofstandardandcustomsoftwarecomponents, generallyabsorbasignificantfractionofthetotaldevelopmentbudgetofanewinstrument. 11, 14, 15, 29

rawdata Thedataextracteddirectlyfromaninstrumentorobservation; sinceitisuncalibratedanduncorrected, itisgenerallyoflittleusetothosenotintimatelyfamiliarwiththeinstrument(seeSect. 1.4). 10, 11

RepresentationInformation TheinformationthatmapsaDataObjectintomoremeaningfulconcepts(OAIS).11, 13, 17, 19, 24, 28

RepresentationNetwork The set of Representation Information that fully de-scribesthemeaningofaDataObject. RepresentationInformationindigitalformsneedsadditionalRepresentationInformationsoitsdigitalformscanbeunderstoodovertheLongTerm(OAIS).24, 28

SIP SubmissionInformationPackage: AnInformationPackagethatisdeliveredbytheProducertotheOAIS foruseintheconstructionofoneormoreAIPs(OAIS).20, 28

SKA SquareKilometreArray: alowfrequencyradiotelescopewithalarge(onesquarekilometre)collectingarea. 6

STFC ScienceandTechnologyFacilitiesCouncil: theprimaryUK funderoffacility-scalescience, see http://www.stfc.ac.uk. 4, 5, 22

straindata ThefundamentalGW signal. 15

Virgo Italian-Frenchgravitational-wavedetector http://www.virgo.infn.it/. 14

VizieR A repositoryofastronomicalcataloguedataatCDS (seeSect. 1.4.1). 10,11

VO VirtualObservatory: asetofdatasharingargreementsandprotocols. SeeSect. 1.10 (nottobeconfusedwithgridVirtualOrganisations). 5, 19, 20

45

http://ligo.org


http://www.nasa.gov




http://www.stfc.ac.uk

http://www.virgo.infn.it/


IndexSeealsotheGlossary, whichaddition-allyservesastheindexofacronyms

AIDA,33, 35astronomydata, 8–11

Babylon, 10, 18benefits, 21, 22bigscience, 6–17

Caltech, 9climatedata, 23costs, 23, 30–33

datagravitationalwave, 14–16ingest, 33volume, 6, 7

dataproducts, 6, 10, 11, 15, 16, 20,21, 23, 25

DCC lifecycle, 28, 29

GAMA,12

HEP data, 8, 13, 14HerMES,12Herschel, 9, 12Hipparchus, 19Hipparcos, 11

LIGOAdvanced, see: glossary: aLIGODMP,26, 30, 31, 33

OAIS,5, 8, 11, 13, 23, 26–28opendata, 6, 22, 23

privatefacilities, 9proprietarydata, 9, 16, 21, 31Ptolemy, 19

rawdata, 10, 15, 16preservation, 25utility, 23

socialsciences, 17softwarepreservation, 17, 25, 29, 30

UKIDSS,12

virtualobservatory, 19, 20

WFAU,Edinburgh, 20

46