Elastic Quota File System (EQFS)

AmitGudNileshChoudhary

DepartmentofComputerD.Y.PatilCollegeofEngg.

Introduction TypicalNetworkScenario

Differenttypesofuserswithdifferentneeds

Variablequotausage

Notpracticaltosetdifferentquotalimitsforlargenumberofusers

Lossofuserspaceifusersdonotusethequotaallocatedtothemeffectively

Noflexibilty

Some Statistics

At95%ofthetimesalltheusersdon'tuse100%oftheirquota

47%oftheusersuse60%oftheirquota

22%oftheusersuselessthan15%oftheirquota

Source:basedonastudyresultsbyBCCInc.onpopularemailservices

What is EQFS? EQFSisElasticQuotaFileSystem

EQFS:

Providescontrolledflexibilityforuserstoeffectiveyusemorethantheallocatedquota

Handlesvariablequotausage Eliminatestheneedtoassigndifferentquotalimitsforusers

withvariableneeds Providesdisklimitsforanetworkirrespectiveofanyuser

quota Postponesdeletionoffilesoncrossingthequotalimit Extendsthequotalimitonrequirementbyallocatingfree

unuseduserspace

How it works?

User2User1

2

10

User2

User1Free8

How it works? Contd...

User2User1

2

10

Elastic User1

User2User1

3

Free

3

10

How it works?

User2User1

10

Elastic

User1

3

User210 Free

User3

User1

What is EQFS? EQFSisElasticQuotaFileSystem

EQFS:

Providescontrolledflexibilityforuserstoeffectiveyusemorethantheallocatedquota

Handlesvariablequotausage Eliminatestheneedtoassigndifferentquotalimitsforusers

withvariableneeds Providesdisklimitsforanetworkirrespectiveofanyuser

quota Postponesdeletionoffilesoncrossingthequotalimit Extendsthequotalimitonrequirementbyallocatingfree

unuseduserspace

EQFS Operation Elasticfiles Whentomakefileselastic

Whenquotaisfullandyouneedadditionalspace

Whathappenswhenafileismadeelastic Owner'squotaisincreasedbyamountofthatfile'ssize

Thatelasticfilebelongstothesameowner

Theadditionalspaceistakenfromothersunusedspace(0.95)

Whichfilestomakeelastic Fileswithlessimportance Temporaryfiles

Riskinvolved Whenthethresholds(user,disk,group)arereached,theelasticfiles

areacteduponasperthepolicyset(0.05)

Where is EQFS?

EQFSisathinfilesystemlayeraboveVFS

Kernel

EQFS

VFS

UnderlyingFileSystem

EQFS Architecture

Kernelmodule

CharDevice

Mel

RelVFS

EQFSDaemon

DB(GDBM)

KernelSpace UserSpace

Thresholds

EQFSworksaround3Thresholds

UserThreshold

DiskThreshold

GroupThreshold

Thresholds contd...

GrouptempGroupStaff

GroupStudent

USERS

Groupswithsingleuser

Userthreshold

Groupthresholds

EQFS Commands

EQFSprovidesfollowingcommandsfortheuser

Melmakeelasticsyntax:#mel[parameter]filename:pathtothefileoperation:actiontobetakenonthefileparameter:destinationincaseofmove&compress

Relremoveelasticsyntax:#rel

SelShowelasticsyntax:#sel

Benchmarks (using Caldera AIM Independent Resource Suite IX) WithoutEQFS

CPU(thousandopspersecond)

Add Div MultShort 2354400 29160 346830Int 2215568 30119 394525Long 2271768 30708 375312Float 766800129000 432000Double 766800125400 461077

Disk/FileSystem/IO(persecond)

Dirsearches 34950 Copy 56945 KbSeqRead 247048 KbCreate/Close 142300 filesLink/Unlink 54085 pairsDirectoryoperqtions2543912

Benchmarks (using Caldera AIM Independent Resource Suite IX) WithEQFS

CPU(thousandopspersecond)

Add Div MultShort 2354308 29605 346826Int 2215448 30106 394522Long 2271429 30746 375309Float 766670128920 431969Double 766650125379 461075

Disk/FileSystem/IO(persecond)

Dirsearches 34946 Copy 56940 KbSeqRead 247044 KbCreate/Close 142229 filesLink/Unlink 54064 pairsDirectoryoperqtions2543900

Advantages EQFSmaximisestheserverspaceutilization

fortheusers

EQFSmeetsthevariablequotaneeds

Transparentreclaimingmechanism

Avoidtheindividualallocationofquotaforuserswithdifferentneeds,whichisnotpracticalwherethenumberofusersarelarge

Handlesthegroupquotasandkeepstheoverallusagewithincheckwithoutinternalinterference

Postponesthedeletionoffilesunlessthethresholdisreached

Advantages contd...

EQFSis

Independentoftheunderlyingfilesystem

Workswiththestandardquotasystem(libquota,edquota)

LowCPUusage

Transparenttotheuser

Thank You!

FurtherInfo:eqfs.sourceforge.net

Questions