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Impact Summary

The working premise is that all data access from Fermigrid/OSG will be via the ifdh cp command,
with Grid jobs reading and writing locally on worker nodes.

What we are not doing - an immediate dismount of data areas.

  • All Fermigrid file access not using ifdhc to fail.
  • Data movement via ifdhc, which is often around 1 GB/second,
    would switch to the Bestman and Experiment Specific GridFTP servers.
    • These servers do not have the throughput to handle the present load.
    • They do not presently have SLAs appropriate to this production use.
    • The increased load on authentication servers could be an issue
  • There is declining but substantial Auxiliary file activity, directly reading Bluarc.
    • We need a reasonable performance alternate before cutting this off completely.
    • The alternate, access via caches using ifdhc, is in final design and test.

Strawman impact and timeline

  • Hiding data mount points.
    • With ifdhc v1_7_2 , there is no change to server or client loads
    • The primary sources of overloads are eliminated.
    • direct access to Bluearc paths would fail, as desired.
    • This can start 2015 Feb 19 with the release of ifdhc v1_7_2
  • Moving locks from /grid/data to /grid/app or similar
    • No impact, can be done while in use via symlinks
    • This can start anytime, should be done by April 2015, befoer /grid/data moved to the blue3 server
  • /grid/data move to blue3
    • this requires copying up to 20 TB to new disk. Probably a few hours downtime.