Atlas:Analysis Challenge ST

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Site Stress Test --Chollet 12:49, 29 janvier 2009 (CET)


  • Replication of target datasets accross the cloud
  • Preparation of job
  • Generation n jobs per site (Each job processes 1 dataset)
  • Bulk submission to WMS (1 per site)

Test conditions

  • The testing framework is ganga-based. It is currently using LCG backend but it will soon be possible to use PANDA backend as well. Metrics are collected and displayed at
  • Both POSIX I/O and "copy mode" may be used allowing performances comparaison of the 2 modes.
  • ATLAS software release 14.2.20
  • Input DS Patterns used (first one is the preferred one for muon analysis):
   mc08.*.recon.AOD.e*_s*_r5*tid* (this pattern includes all the previous ones)
  • Input datasets are read from ATLASMCDISK and outputs are stored on ATLASUSERDISK (no special requirements there). Input data access is the main issue. No problem on data output
  • Required CPUtime : GlueCEPolicyMaxCPUTime >= 1440 (1 day , typical duration : 5 hours)
  • Jobs run under DN : /O=GermanGrid/OU=LMU/CN=Johannes_Elmsheuser
  • LAN saturation observed in case of 1 Gb network connection between WN and SE.
  • It is possible for sites to limit the number of jobs sent at a time.
  • Test duration : 48 hours

File access modes used by Ganga Jobs

Two access modes may be used during ST tests.

  • (j.inputdata.type='DQ2_LOCAL') : Currently if users are submitting Ganga jobs with the LCG backend, the posix I/O access is the default method to access files
  • (j.inputdata.type='FILE_STAGER') : One of the alternative access mode used by ST tests is the FileStager mode, which copies the input files in a background thread of the athena event loop usinglcg-cp from the local SE to the worker node tmp area. This mode still needs a bit of improvements to gain full stability, but as demonstrated good performance during ST at some (but not all) sites.

Target and metrics

  • Nb of jobs : Few hundred up to 1000 jobs/site
  • Rate (evt/s) : up to 15 Hz
  • Success rate (success/failure rate) > 80 %
  • CPU utilization : CPUtime / Walltime > 50 %

Results and Monitoring