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ALICE RRB-T 2001-661 ALICE Computing – an update F.Carminati 23 October 2001
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2ALICE RRB-T 2001-66October 2001 ALICE Computing ALICE computing of the same order of magnitude than ATLAS or CMS Major decisions already taken (DAQ, Off-line) Move to C++ completed TDRs all produced with the new framework Adoption of the ROOT framework Tightly knit Off-line team – single development line Physics performance and computing in a single team Aggressive DC program on the LHC prototype ALICE DAQ/Computing integration realised during data challenges in collaboration with IT/CS and IT/PDP
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3ALICE RRB-T 2001-66October 2001 ALICE Physics Performance Report Evaluation of acceptance, efficiency, signal resolution Step1: Simulation of ~10,000 central Pb-Pb events Step2: Signal superposition + Reconstruction 10,000 events Step3: Event Analysis Starting in November 2001 Distributed production on several ALICE sites using GRID tools
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4ALICE RRB-T 2001-66October 2001 ALICE GRID resources Yerevan CERN Saclay Lyon Dubna Capetown, ZA Birmingham Cagliari NIKHEF GSI Catania Bologna Torino Padova IRB Kolkata, India OSU/OSC LBL/NERSC Merida Bari http://www.to.infn.it/activities/experiments/alice-grid 37 people 21 insitutions
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5ALICE RRB-T 2001-66October 2001 Writing to local disk Migration to tape ALICE Data Challenge III Need to run yearly DC of increasing complexity and size to reach 1.25GB/s ADC III gave excellent system stability during 3 months DATE throughput: 550 MB/s (max) 350 MB/s (ALICE-like) DATE+ROOT+CASTOR throughput: 120 MB/s, MB/s 2200 runs, 2* 10 7 events, 86 hours, 54 TB DATE run 500 TB in DAQ, 200 TB in DAQ+ROOT I/O, 110 TB in CASTOR 10 5 files > 1GB in CASTOR and in MetaData DB HP SMP’s: cost-effective alternative to inexpensive disk servers Online monitoring tools developed MB/s
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6ALICE RRB-T 2001-66October 2001 ADC IV (2002) Increase performances (200MB/s to tape, 1GB/s through the switch) Focus on computers and fabric architecture Include some L3 trigger functionality Involve 1 or 2 regional centres Use new tape generation and 10 Gbit Eth. LDC’sGDC's ~1000MB/s Phys data 1 Centre 2 Phys data 1 Centre 1
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7ALICE RRB-T 2001-66October 2001 Production Environment & Coordination P.Buncic Simulation production Reconstruction production Production farms Database organisation Relations with IT & other comp. centres Detector Projects ALICE Offline Computing Structure Framework & Infrastructure F.Rademakers Framework development Database technology HLT Farm Distributed computing (GRID) Data Challenge Industrial joint Projects Tech. Tracking Documentation Simulation A.Morsch Detector Simulation Physics simulation Physics validation GEANT 4 integration FLUKA integration Radiation Studies Geometrical modeller International Computing Board EC DataGRID WP8 Coordination DAQ P.Vande Vyvre Reconstruction & Physics K.Safarik Tracking Detector reconstruction HLT algorithms Global reconstruction Analysis tools Analysis algorithms Calibration & alignment algorithms Technical Support Management Board Regional Tiers ROOT FrameWk Data Challenges HLT algorithms Offline Board Chair F.Carminati Software Projects
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8ALICE RRB-T 2001-66October 2001 CERN Off-line effort strategy ALICE opted for a light core CERN offline team… 17 FTE’s are needed: for the moment 3 are missing plus 10-15 people to be provided from the collaboration To be formalised by a Software Agreements/MOU Good precedents GRID coordination (Torino), ALICE World Computing Model (Nantes), Detector database (Warsaw) We would like to avoid a full MoU! Imbalance between manpower for experiments and GRID Enough people pledged for GRID Both needed for the success of the project Candidate Tiers’ should provide people during phase 1 We have to design the global model, and we need outside people to develop it with us
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9ALICE RRB-T 2001-66October 2001 CERN Off-line effort strategy Staffing of the offline team is critical otherwise Coordination activities jeopardized (cascade effect) Data Challenges & Physics Performance Report delayed Readiness of ALICE at stake Efforts are made to alleviate the shortage Technology transfer with Information Technology experts IRST Trento, CRS4 Cagliari, HP Recruit additional temporary staff (Project Associates) Adopt mature Open Source products (e.g. ROOT) Ask support from IT for core software (FLUKA, ROOT) Recommended by the LHC Computing Review
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10ALICE RRB-T 2001-66October 2001 Conclusion The development of the ALICE Offline continues successfully The understaffing of the CORE Offline team will soon become a problem as its activity expands Additional effort will be asked to the collaboration We hope to avoid a MoU here and work with bilateral software agreements (a la ATLAS) Where the GRID project has found a good resonance the experiment part still need to be solved
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