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LHCb usage of Tier2s

LHCb usage of Tier2s. LHCb Computing Model. Guidelines Evaluate computing needs for all activities Simulation Real data processing Analysis Map it to expected resources at Tier0, Tier1s (6) and Tier2s (including non MoU) Large needs for simulation (precision experiment)

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LHCb usage of Tier2s

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  1. LHCb usage of Tier2s

  2. LHCb Computing Model • Guidelines • Evaluate computing needs for all activities • Simulation • Real data processing • Analysis • Map it to expected resources at Tier0, Tier1s (6) and Tier2s (including non MoU) • Large needs for simulation (precision experiment) • Use full power of Tier2s (and others) for simulation • Minimize potential file access problems • For processing and analysis • TDR baseline • Run processing applications at Tier0/CAF and Tier1s • For reprocessing, largely use also the Online HLT farm • Estimated ~50% of needs, but needs developments • Run simulation primarily at Tier2s • Use any opportunistic site PhC

  3. LHCb Analysis • Batch analysis • Using Grid facilities at Tier0 and Tier1s • All stripped DSTs available at all sites • MC DSTs at 3 sites (CERN + 2) • Storage of output (microDST, Ntuple…) on Grid SE • TxD1 storage (LHCb_USER token) • Expected number of selected events is small (<107 <~1 TB) • End user analysis • Well feasible on desktop / laptop • Assume Tier3/4: not part of Grid activities • Under institute responsibility to set up: • Storage and dataset replication • Software installation • Develop multi-core/processor interactive programming (GaudiParallel, in collaboration with LCG-AA/PH-SFT) PhC

  4. LHCb Analysis on Tier2 ? • First goal is to get it running reliably on Tier1s • Experience a lot of file access problems • Only 2 flavors (Castor and dCache) • Full time job to follow up on 7 sites • No central manpower for supporting more sites / flavors • How could a Tier2 be used for analysis? • Grid resources are shared • LHCb does not want to support “national computing” • Our CPU requests are balanced between Tier1 and Tier2 • Therefore analysis should come from additional resources • Local LHCb group(s) should be involved in the support • Dataset assignment • Problem resolution (data access, software installation…) • Proposal • Investigate feasibility with a few selected sites (1-2) • Define a model that doesn’t increase the load on central support PhC

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