User Board - Supporting Other Experiments Stephen Burke, RAL pp Glenn Patrick

9 th September 2009 UB – GridPP 23 2 User Board Meets ~ 3 times a year Representatives of all experiments Allocates CPU and disk at the Tier-1 –And in principle the Tier-2s Also discusses any topics of interest to users –But not a technical forum, mainly about policy –Once operational, the LHC experiments will obviously be the main strategic priority. However, all attempts will also be made to resource the non-LHC experiments within the limits of available funding.

9 th September 2009 UB – GridPP 23 3 Resources for non-LHC VOs Small experiments seem to prefer to use the Tier-1 –So far the Tier-1 CPU has been under-utilised, but that may change when the LHC starts taking data –Storage can be allocated to small VOs in Castor, but its a complex and heavyweight system if you just want a few TB of disk storage Needs discussion with the Tier-1 team to set up, and takes some time, so give notice well in advance Disk server size gives a quantised allocation –Tier-1 team have to give priority to LHC experiments, but they do support everyone Consider the Tier-2s too –Total resources are comparable to the Tier-1 –DPM Storage Element is much simpler than Castor –Grid model: jobs can run anywhere –Local support if you use your local site

9 th September 2009 UB – GridPP 23 4 Other resources VOMS server: maintained by Manchester File Catalogue: can use the LFC at the Tier-1 WMS (aka Resource Broker): primary at the Tier-1 –Other instances at Glasgow and Imperial User Interface: should be one at your local site –UI at the Tier-1 is restricted, but access can be granted if its needed GANGA: job submission and management toolGANGA –Developed in the UK for ATLAS and LHCb, but now widely used and supported Documentation –GridPP web site:

9 th September 2009 UB – GridPP 23 5 Support for small VOs Janusz Martyniak: software/service supportJanusz Martyniak –Running an LFC –Support for use of VOMS, BDII, … –Gridification Stephen Burke: documentation, advice, troubleshootingStephen Burke –Use of MyProxy –Use of SRM, lcg-utils etc –Middleware support and debugging –Pointers to documentation Ask for help via UB or directly to us –New startup VOs need particular help to get started

9 th September 2009 UB – GridPP 23 6 Other support channels Two weekly meetings, both in EVO: –dteam, Tuesdays at 11 am deals mainly with Tier-2 issues –Tier-1 weekly, Wednesdays at 13:30 –Both have slots for any experiment to discuss problems and requirements GGUS tickets –To report specific technical problems with any Grid site or middleware – Training –Provided for EGEE (and EGI?) by Edinburgh (NESC) –Not sure if any GridPP users have tried it –Do we need something customised for small HEP VOs?

9 th September 2009 UB – GridPP 23 7 Mailing lists UKHEPGRID –General announcements, low volume GRIDPP-USERS –Originally intended for user discussion, but never used in practice –Now used for user-oriented announcements TB-SUPPORT –Discussion list for site admins –Fairly active, user questions would probably get a helpful answer dteam –Internal list for the dteam, but users could address questions to it GRIDPP-UB –UB mailing list, low volume discussion of resource/policy issues

9 th September 2009 UB – GridPP 23 8 General comments Please ask for help!!! –Sometimes people seem reluctant The Grid has a reputation for problems – some justification for that but people may give up too easily –Need to follow up if things arent moving –Sites would like to know whats happening, good or bad –Dont just ask one person, they may be busy or not know the answer It is possible to solve Grid problems … –… sometimes … –Or else there is usually another way – maybe not ideal but things can be made to work, many users are using the Grid successfully

9 th September 2009 UB – GridPP 23 9 Random examples Maradona error –Major cause of job failure since forever –Seems cryptic, hard to understand, people just ignore and resubmit The Grid is broken! –There are several possible causes and it can take some effort to track down, but it can be fixed, it isnt inevitable GGUS ticket to site Cant delete directories in SRM –Technically possible, but there was indeed no easy way –Submitted a savannah bug, fix took a few months to get to production –Now you can do it (lcg-del –d) Using MyProxy to automatically renew a VOMS proxy –Not obvious, but easy when you know how –Now documented:

9 th September 2009 UB – GridPP Summary LHC experiments are bound to get priority, especially as data-taking starts, but GridPP does support the other experiments too UK CPU resources are substantial –A small fraction of a large system is still a lot –Scope for opportunistic use when LHC VOs are quiet The original rationale for the Grid Storage is harder because its long-term –But small experiments probably dont need a huge amount Consider Tier-2 as well as Tier-1 Ask for help, it is available –Dont give up!

9 th September 2009 UB – GridPP UK Grid usage