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STEP’09: Last challenge before data taking. Patricia Méndez Lorenzo (CERN, IT/GS) ALICE Offline Week Grid Status & Experience session CERN, 24/06/09. Outlook. CCRC’08: Reminder What is STEP’09: Origin STEP’09 for ATLAS, CMS and LHCb STEP’09 for ALICE Goals and Results

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step 09 last challenge before data taking

STEP’09: Last challenge before data taking

Patricia Méndez Lorenzo (CERN, IT/GS)

ALICE Offline Week

GridStatus & Experience session

CERN, 24/06/09

outlook
Outlook
  • CCRC’08: Reminder
  • Whatis STEP’09: Origin
  • STEP’09 for ATLAS, CMS and LHCb
  • STEP’09 for ALICE
    • Goals and Results
  • Summary and Conclusions

STEP'09: last challenge before data taking

what is step 09 ccrc 08 reminder
Whatis STEP’09: CCRC’08 reminder

WLCG Common ComputingReadiness Challenge 2008 (CCRC’08)

  • It was the first big WLCG Service Challenge whichjoined the 4 experimentstogether
  • Proposed by CMS and ATLAS during the pre-CHEP WLCG WS in Victoria (2007)
    • Goal:measurement of the readiness of the Grid services and operationsbefore the real data taking
    • Complementary to the experimentsFullDressRehearsals
    • Distributed in two phases: Feb and May 2008

STEP'09: last challenge before data taking

alice results during the ccrc 08
ALICE Resultsduring the CCRC’08

Slidestakenfrom the CCRC08 Post-Mortem WS at CERN (June 2008)

STEP'09: last challenge before data taking

w hat is step 09 origin
Whatis STEP’09: Origin

WLCG ScaleTesting for the Experiment Program at the WLCG 2009: STEP’09

  • Proposed by CMS during the WLCG pre-CHEP WS in Prague (2009)
    • Scheduled for June 2009
  • Similar scope to CCRC’08 withspecialemphasis to data management (data recording, MSS behaviour and transfers)
    • STEP’09 post-mortem in July
    • All experimentspresentedtheir programs during WLCG GDB in April 2009

STEP'09: last challenge before data taking

step 09 for cms
STEP’09 for CMS

STEP'09: last challenge before data taking

In commonwith ALICE

step 09 for atlas
STEP’09 for ATLAS

STEP'09: last challenge before data taking

In commonwith ALICE

step 09 for lhcb
STEP’09 for LHCb
  • Participation in STEP’09 as part of theirspecific Full Experiment Test (FEST’09)
  • LHCb goals
    • Data injection into the HLT farm
      • File size canbetuned
    • Distribution to T1 sites
      • Using standard share
    • Reconstruction at T1 sites
      • Long enough queues at the sites are needed
    • Storage Requirements
      • 3.5 TB/day for RAW (T1D0) at Tier0
      • < 1TB/day for RAW at Tier1s

STEP'09: last challenge before data taking

In commonwith ALICE

step 09 for alice
STEP’09 for ALICE
  • Gridactivities
    • Replication T0->T1
      • PlannedtogetherwithCosmics data taking, or
      • Repeat the exercise of CCRC’08 withsame rates (100MB/s) and same destinations (All T1 sites)
    • Re-processingwith data recallsfrom tape at T1
      • Highlydesirableexercise, data alreadyavailableat the T1 MSS storage
  • Non-Gridactivities
    • Transfer rate tests from DAQ@PIT to CASTOR
      • Validation of the new CASTOR and xrootd for RAW
      • Criticallydependent on the availability of CASTOR v2.1.8
      • Transfer rate test coupledwith the 1st pass reco@T0

STEP'09: last challenge before data taking

alice n on grid activities
ALICE non-Gridactivities
  • RAW data transfersfrom PIT to CASTOR
    • Basicallyvalidated
    • The goal was 1.25GB/sec for one week (justfinished)
    • DAQ managedto fill the entirealicedisk pool (850TB)
  • Validation and feedback of the CASTOR v2.1.8 and xrootd
    • Very positive results
    • the xrootd copy P2->Diskisbasicallyvalidated
    • second part isdisk->tape copy (to a recyclabe pool of tapes) with the same speed of 1.25GB/sec (thisisPb+Pb full rate)
      • Activitystillongoing
  • Pass 1 reconstruction of RAW data at the T0
    • Stillpending

STEP'09: last challenge before data taking

alice grid activities results
ALICE Gridactivities: results

ALICE began the STEP09 exercise the 1st of June and finishedit the 18th of June

  • Production results
    • New record of 15000 concurrent jobs by the 1st of June

STEP'09: last challenge before data taking

New MC cycle

problems faced by alice production
Problemsfaced by alice: Production
  • Instabilitieswith the CREAM-CE system at CERN
    • The system has facedinstabilities for somedays
    • Fullyaffecting the production by the 17th of June
      • Both CREAM-CE services down
      • This morning the system came back in production
    • A power cut by the 18th of June
      • voalice03 (CREAM VOBOX) could not berecovered
      • In addition the VOBOXES willbe out of warrantyat the end of the year
      • 4 VOBOXES have been required (2 production, 2 backup)
  • New site entered production: CESGA (Santiago de Compostela, Spain)
    • 800 jobs submitted for 29 CPUs
    • Site wasreporting 0 jobs running/waitingthroughVOview
    • ALICE has changed the query to the info system based in VOview

STEP'09: last challenge before data taking

alice fts transfers
ALICE FTS transfers
  • General result: Verysuccessfullexerciseduring the whole STEP09 period
    • New FTD module in production
  • During the wholeperiod the 6 T1 sites wereavailablewith few issues alwayssolved in the day
  • Very good support of the FTS experts during the wholeperiod

STEP'09: last challenge before data taking

ALICE requirement

problems faced by alice transfers
Problemsfaced by alice: Transfers
  • Pre-staging on files: MEETING WITH FIO STILL PENDING
    • The operationtakesforever
    • New files have tobecreatedinsteadof pre-stagingthosealreadyexisting
    • Asked CMS and LHCb for theirownprocedures
      • CMS has implemented a Phedex utility at the client level for CASTOR sites able to make the pre-staging.
        • Comparisonsbetweenmethodsusing SRM APIS, Manualpre-staging and also the samePhedex
        • The staging speed in the 3 cases is comparable and
        • CMS usedthe STEP09 exercise to define the best way to define the pre-staging
      • LHCbisusing GFAL libs to make an asyn. pre-staging of the files

STEP'09: last challenge before data taking

problems faced by alice transfers1
Problemsfaced by alice: Transfers
  • Files overwritting: SOLVED
    • This procedurewouldallow to perform a previousremoval of the alreadytransferred file
    • ALICEimplementedcorrectly the corresponding option howeverstillfailing
    • FTS experts involved in the discussion:
      • the 'overwrite' flag isproperlypassed to the FTS agent, howeverit selects SRMv1 endpointinstead of SRMv2.2
      • Whilechecking the details ALICE should chose the qualified SURL to ensure the usage of SRMv2.2.

STEP'09: last challenge before data taking

problems faced by alice transfers2
Problemsfaced by alice: Transfers
  • Issues per site
    • NDGF using a wrong SURL whiletranferring files: SOLVED
    • RAL: Permission denied to write in the corresponding SE area (twice): SOLVED
    • SARA: No spaceavailable (twice): SOLVED
    • FZK: gridFTP issue. There was a problem of dcache pools beeingfilled up, and also a gpfsproblem of not correctlyreportingspace: SOLVED
    • This week CERN: Transfersstucked for more than 60h. Stillunder investigation
      • It seemssome sites do not allow concurrent transfers

STEP'09: last challenge before data taking

summary and conclusions
Summary and conclusions
  • STEP’09 has been the 2ndmulti-VOexercisebefore the real data taking
  • Proposed by CMS during the pre-CHEP WS in Prague
  • ALICE emphasize the testing of the Data Management elements of the computing model
    • Key elements for the 4 LHC experiments
  • ALICE results: Very good behaviour in terms of production, MSS@T1 and FTS transfers
  • The 4 LHC experimentswillpresenttheirresultsduring the new STEP’09 post-mortem WS in July at CERN (9-10 July)

STEP'09: last challenge before data taking