ALICE RRB-T ALICE Computing – an update F.Carminati 23 October 2001

2ALICE RRB-T October 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

3ALICE RRB-T October 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

4ALICE RRB-T October 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 37 people 21 insitutions

5ALICE RRB-T October 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

6ALICE RRB-T October 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

7ALICE RRB-T October 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

8ALICE RRB-T October 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 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

9ALICE RRB-T October 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

10ALICE RRB-T October 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