Uploaded image for project: 'Lustre'
  1. Lustre
  2. LU-10278

lfs migrate: make use of direct i/o optional

    Details

    • Type: Improvement
    • Status: Resolved
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: Lustre 2.11.0
    • Labels:
    • Rank (Obsolete):
      9223372036854775807

      Description

      In order to avoid cache thrashing, lfs migrate currently uses direct i/o to copy file contents, which may leads to significantly different performance compared to normal (non-O_DIRECT) i/o, cf. for example the discussion at http://lists.lustre.org/pipermail/lustre-discuss-lustre.org/2017-November/015112.html. Internally, we've measured even more extreme differences where O_DIRECT throughput performed at 1/10th the normal rate. Therefore, I'd suggest to leave the choice between normal and direct i/o to the caller of lfs migrate by adding a new option N/-non-direct that suppresses to O_DIRECT flag in the open() call of the source file. Patch to follow.

        Attachments

          Issue Links

            Activity

              People

              • Assignee:
                emoly.liu Emoly Liu
                Reporter:
                kobras Daniel Kobras (Inactive)
              • Votes:
                0 Vote for this issue
                Watchers:
                5 Start watching this issue

                Dates

                • Created:
                  Updated:
                  Resolved: