Organisation

•Management and Policy Group (MPG):Responsible for setting and policy decisions and resolving any issues concerning fractional usage, acceptable usage policy etc. within the Tier-2.

•Technical and Support Group (TSG):Responsible for the technical coordination between the different institutes within the Tier-2 so as to enable the effective operation of the Tier-2 Centre as defined by the MPG. The Technical Support Group meets each two weeks to discuss technical issues and solutions. A technical mailing list is used for daily operation and support. In addition a wiki is used to capture persistent information like configuration scripts, monitoring links,contact lists.

http://wiki.gridpp.ac.uk/wiki/London_Tier2Failure ManagementThe LT2 staff has 16 persons which is 6 Full TimeEquivalent (FTE). 67% of the FTE is Funded (GridPP,EGEE) and the remaining 33% are unfunded (non GridPP orEGEE) efforts.Technical issues in the LT2 are solved by two type of support:•Local Support: Involved when remote staff cannot help(network failures, hardware failures).•Global Support: Involved in most software failures cases.In that case the mailing list, wiki and telephone are used toaddress the issues.

The table on the right shows the staff availability for both type of support. Each person has a time slot allocated in the week. The global support coverage is 100%. Each day has at least one person able to solve a problem.

The Local support coverage is more problematic since itwould require a high mobility of persons between the sites.The lower part of the table shows in red the time slots wherelocal support cannot be achieved. It translates to an efficiencyof 76% (fraction of days covered). The asymptotic efficiencywhich counts the fraction of covered days where only one person is in charge is very good (89%). It indicatesthe available human resources are efficiently used but moreis needed to have full coverage during the week.

London Tier 2The London Tier2 (LT2) consist Five Universities with seven LHC Computing GridSites (LCG). University College London (UCL), Imperial College London (IC) andQueen Mary University of London (QMUL) are close to the centre of the town. BrunelUniversity (BRUNEL) and Royal Holloway (RHUL) are further on the west side of thetown. All the five universities are connected through the London Metropolitan Network.UCL, Imperial College and Queen Mary having a one Gb/sec network connection.

Imperial College eScience centre (IC-LeSC) and recently the UCL computing centre (UCL-CCC) is using the Sun Grid Engine. More information can be found at: http://wiki.gridpp.ac.uk/wiki/LCG-on-SGE.

With the LCG 2.7.0 release we aim to support the same set Virtual Organization (VO) on all the sites. In doing this we will increase the utilization of the available resources. The Figure below summarizes the relative contribution in computing hours for the VO we are currently supporting. With the 2.7.0 release we will support three additional VO (Sixt, Zeus, T2K)

The LT2 totals 865 CPU (850 KSI2K) and 30TB of storage. This is implemented in heterogeneous hardware systems across the sites.

The Figure on the right shows the CPU distribution across the different sites. All the sites are using PBS/MAUI for their local scheduler.

LondonTier2