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www.pegasus.lse.ac.uk ¦ [email protected] of Virtuality –Athens 2009.

Particle Physics and Virtuality: a discussion on researching a virtual distributed community for the LHC at CERN. Dr. Will Venters LecturerInformation Systems and Innovation GroupDepartment of ManagementThe London School of Economics and Political [email protected]

This research was undertaken as part of PegasusEPSRC: Grant No: EP/D049954/1www.pegasus.lse.ac.uk


Overview

The socio-material nature of “virtuality” within a truly virtual domain:

Particle Physics Grid infrastructure

Tentative Research Question:

How is the Grid shaped by the agency of users & SysAdmin?

Theoretical Framework: Mangle of Practice

Conclusion: Virtual ‘vs.’ physical… User ‘vs.’ Sysadmin

www.pegasus.lse.ac.uk ¦ [email protected] of Virtuality –Athens 2009.EPS Conference on High Energy Physics, Manchester 23 July 2007


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Data Deluge.

~100,000,000 channels, 600,000,000 collisions per second,.

Searching for Higgs Boson – “1 person in 1000 worlds, or a needle in 20 million haystacks”

12-14 million gigabytes per year.

100k CPUs, 40PB disk, 40PB tape.


CERN’s computing hall – largest of 237 sites on the Grid.


But what is a Grid?

“Coordinated resource sharing and problem solving in dynamic, multi-institutional virtual organizations" (Foster, 2001)

… which “enable disparate groups of organisations and/or individuals to share resources in a controlled fashion, so that members may collaborate to achieve a shared goal” (Foster, 2001)

Enable re-scaling of practice (Hey at al. 2002)


Why Particle Physics?

“Elite science”

Tradition of global collaborations (Traweek 1988).

Collaborative working practices (Knorr-Cetina 1999)

Successful advanced ICT (Web, Cray, Open-Source, Server-farms).

Advanced computer users.


Theoretical Framework Andrew Pickering (1995,2009) – Mangle of Practice

Performative; Science as emergent interplay of human and material agency – reciprocally and temporally constituted (Pickering 1995)

Responds to call to consider materiality of technology (Orlikowski 2001; 2007) but not reifying technology nor social practices.

World is a “lively place full of agency” (Pickering 2002)

Human Intentionality. The focal purpose – “a relatively fixed image of some future state”.

Human and material agency are “mutually and emergently productive of one another” (Pickering1993) through a dialectic – the Mangle of Practice.

But the Mangle does not respond to the collective well (Pinch 1999)

Communities of Practice (Wenger 1998) as conceptual framework for the collective.


Example Virtual Organisation: ~2300 globally distributed physicists working on the CMS experiment


CoP – “CMS Physicists”

Grid is: “just a processing machine that sits there”

“People want enough disk space, they want fast CPUs that they can run there usually very inefficient programmes on, and they want it 24/7 and during Christmas!”

Physicists are “very dirty programmers… they usually want the fast hack”. They will “fly to CERN taking a stack of writable CDs and flying back to London… Only if you have a Grid at a workable level is it an alternative”


Running a CRAB job

Workload Manager Middleware (part of Grid) reflects SysAdmin…

CRAB (CMS Remote Analysis Builder)

Operating Crab (and LCG) within the CMS community:

“People learn…by getting a working script from someone… and starting from there and trying to run it and trying to modify it to suit there needs”.

Scripts are regularly e-mailed to others to help with problems and provide advice. FAQs, documentation, Blogs and Wikis are used developed.


Resistance & Accommodation

“Impossible to monitor what is going wrong”

Crab gets blamed… “there is a school of thought that the last letter should be changed to P”

Unclear support: No “local” systems administrators.

Crab creates a barrier… “invariably the problems falls between [Grid and CMS]. So Grid people don’t know what I am talking about… and CMS software people say it’s a Grid problem.”


Change in practice

New work practices emerge

“Being a systems administrator for particle physics must be hell, they will want different systems for everything, and they are all quite savvy, they will tune everything….”

“Just kill problematic jobs which take too long to run”

Black-list and White-list feature for testing/management.#Ce_black_list=*.fnal.gov,*.ral.ac.uk

#Se_black_list=*.fnal.gov,*.ral.ac.uk#Ce_white_list=*.cern.ch#Se_white_list=*.cern.ch


Grids: “coordinated resource sharing” (Foster & Kesselman 1998).

“In practice the way I operate is; I find out where my data is and tell this Crab tool where to go”.

“the only way it works is if you find out where the data is and they you tell the thing to send it there.”

Doing this “releases more time to make [physics analysis] happen”


SysAdmin

Experiments “develop independent monitoring systems that report independently the situation of the infrastructure as they see it. Not as the managers see it. “

“If there was a user sitting in isolation they would have to use what we provide…. But they all work for experiments with lots of influence and resources and everything. And which occasionally, possibly often, have very high influence in some of the sites as well, they can ask the sites to install various services. So they can bypass stuff.”

But “workload management might be scrapped, because it would be investment in something useless”


Tentative contributions

Battle of Intentionality of PP and SysAdmin as infrastructure is performed.

Fundamental change in the Infrastructure… Not just “Shaping/innovation”

Norms of behaviour – tinkering, bricolage, improvisation.

Questions relationship between “user” and “developer/maintainer” (Woolgar)

Cloud computing – Role of ICT in organisations?


Will Venters; [email protected]

www.pegasus.lse.ac.uk ¦ [email protected] images of virtuality –athens 2009. particle physics...

Documents

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