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Minutes 19 January 06

  • Phone: Barbara(CNAF), Eric(FNAL), Silke(GridKA), Stefan(Oxford), Gancho (ATLAS), Jerome(AMI), Iris(BNL), Gordon(RAL), Marco(LHCb), Sacha(ATLAS)
  • @CERN: Luis(3D), Dirk(3D), Eva(3D), Ioannis(POOL), Radovan(POOL)

  • General points:
    • DB readiness workshop 6 Feb
      • CNAF will be represented by Barbara, she will come to CERN
      • LHCb will be represented by Marco
      • GridKA will be represented by Andreas Heiss in person, Doris and Silke plan to join via VRVS
      • BNL will be represented by Iris, she will join via VRVS
      • Dirk is finalising the agenda (input still welcome for a few days)
    • POOL releases: next one early next week
    • Grid User support and problem tracking: * will affects equally CERN T0 and Tier 1 sites * Flavia Donno has agreed for a presentation during the next meeting
  • Roundtable Tier1 sites status
    • CNAF (Barbara): some problems in test cluster - block corruption, futher investigation is needed, hardware setup problem not excluded
    • Dirk propose to use the mailing lists to log these problems and make possible to Tier0 dbas look at them
    • GridKA (Doris): No progress on the network problem. Allocated 2 Squid nodes for CMS, to be setup soon
    • BNL (Iris): sporadic node reboot problems in cluster setup for production, investigating timeout settings
    • RAL (Gordon): Squid nodes up and running, database h/w expected to arrive soon, no problem expected for setup in time for production
    • Dirk has by know updated the status table
  • Roundtable testbed test progress
    • Gancho (online-offline ATLAS tests): getting familiar with David Front's test code. He will contact Eva when ready to start
    • Birger: tests can be restarted as IN2P3 problem is gone
    • Stefan: investigating wait time, try to find where the time is spend, need should contact CERN or RAL DBA for help
    • Marco: CERN to RAL database connection has been setup, first replication run should no problems, more functionality tests planned
  • Data consistency for Applications using FroNtier/Squid
    • presentation by Luis
    • slides available on the agenda
    • Summary
      • FroNTier + SQUID (and consequently POOL/FroNTier) can not avoid shipping stale (cached) data after db updates/deletes
      • Luis explained some of the inconsistencies arising an proposed rules to avoid them
      • Policy to be used by CMS is to separate cached payload date (no updates/delete allowed) from un-cached meta-data used to find payload data (eg IOV)
        • SQUID caching needs to be explicitly (client application) disabled for lookup data - requests will always go to Frontier server and DB at T0
        • CMS conditions (and other experiments) applications planning to use FroNTier/SQUID need to take this into account.
        • Frontier client should expose API for caching control
        • Ioannis proposed that Frontier plugin should use this API eg for a list of tables (eg specified as a POOL plugin)
        • Current CMS tests have likely been done with "all cached" or "nothing cached" policy of the current Frontier client and plugin. To be confirmed by Lee
        • Details of cache control need to be defined by Frontier/POOL team to allow for more realistic tests of workload
      • Luis outlined in his slides possible automated invalidation schemes based on back-end database triggers on update/delete
      • Even though logically possible this invalidation seems difficult to deploy in a large and distributed collection of squid caches

  • AMI distribution tests between IN2P3 and CERN
    • master database at IN2P3, replica database at CERN
    • Eva will contact Jerome to coordinate the setup and tests
  • VOMS replication tests
    • VOMS team (CNAF) would like to test setup read-only replication
    • Dirk proposed VOMS team discuss their test schedule with the VOMS responsible (Maria Dimou) come up with a concrete test proposal and schedule
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Topic revision: r2 - 2006-01-24 - DirkDuellmann
 
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