GlueX Containers Meeting, March 30, 2018

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GlueX Containers Meeting
Friday, March 30, 2018
11:30 am EDT
JLab: CEBAF Center L207
BlueJeans: 968 592 007



Present: Sean Dobbs, Mark Ito, Thomas Britton, Beni Zihlmann, Zisis Papandreau, David Lawrence, Richard Jones

  • Atlas and CMS and OSG et al. designed a grid to do raw data reconstruction.
    • MC was not considered a problem
    • The tiered system has as a component the raw data distribution system
    • software and databases were staged as "image files"
    • originally developed at SLAC
    • redirector: directory service, contains meta data (file locations)
    • on the local host open a file just like a local file except file name is replaced with a URL like root://<name of catalog><IP name of redirector><file name>, triggers an open over network
    • redirector refers opener to site, a data connection is opened on site, data streamed over connection
    • our bandwidth requirements should be OK
    • David: at NERSC, 64 threads on a single node, reconstruction, 4 MB/s read rate
    • there is a caching system, if everything is mostly working cache, is not heavily used
  • UConn demo system
    • redirector service started
    • 50 servers, each serving a few files
    • 10 Gb pipe
  • Client side responsibilities
    • download and build XROOTD
    • set-up ld_preload[?]
    • open calls get intercepted and redirected to XROOTD system
  • Sean has also messed with setting up an XROOTD server
  • David mentioned the XROOTD idea to Amber Boehnlein, she seems supportive
    • Consensus that it would be best if infrastructure supported at JLab on the submit host
    • Could be used for both raw data and random trigger files
    • Richard and Thomas will work on staging random triggers on UConn demo system
  • David: Chip may allow Physics to use 5% of future LQCD KNL cluster
  • David: planning for summer campaign at NERSC, reconstruction
    • Sean: candidates for off-site resource campaigns:
      • ρ and ω yield measurements with 10 or 20 files per run
      • 2017 data: 2 periods, low intensity and high intensity
      • 2018 data: 4 periods