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  1. Lustre
  2. LU-17300

Avoid creating new dir/file/object on newly added MDT/OST

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Details

    • Bug
    • Resolution: Unresolved
    • Minor
    • None
    • Lustre 2.15.0
    • None
    • 3
    • 9223372036854775807

    Description

      When a new MDT is added to a filesystem without no_create then the DNE MDT auto-balance is enabled, then a new subdirectory could be created on the new MDT relatively quickly after it is added to the filesystem. However, it might take a few seconds for the addition of the new MDT to be propagated across all of the clients, so there is a small risk that an MDT is holding a subdirectory that another client is not yet aware of.

      I think there are two relatively simple solutions to this:

      • don't consider a new MDT for subdirectory creation for, say, 30s after it appears in the config, to give other clients a chance to discover it
      • if a new MDT is used for a subdirectory that is not in the config, then the client should pull the config from the MGS to see if it was newly added.

      The similar situation exists with new OSTs added to an existing files, where the MDS is notified about an OST addition and allocates an object to a file, but the client has not yet been notified about the new OST and will return an error accessing the file. The solution in this case is the same - avoiding to use a new OST for object allocation for ~30s after the OST is added, and similarly for clients to pull the config from the MGS to see if the OST was newly added.

      This ticket is tracking the first issue - don't create new subdirs/files/objects on newly-added targets. LU-17344 is separately tracking the client more gracefully handling the presence of subdirs/files/objects on an MDT or OST that it doesn't know about.

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        Issue Links

          is cloned by

          Bug - A problem which impairs or prevents the functions of the product. LU-17334 Client should handle dir/file/object created on newly added MDT/OST

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Resolved
          is related to

          Improvement - An improvement or enhancement to an existing feature or task. LU-17327 Write conf-santity test case for online OST and MDT addition

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Open
          is related to

          New Feature - A new feature of the product, which has yet to be developed. LU-14792 DNE3: enable filesystem-wide default LMV

          • Major - Major loss of function.
          • Resolved

          New Feature - A new feature of the product, which has yet to be developed. LU-12036 Add 'no_create' mount option to create new OSTs inactive

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Resolved

          Improvement - An improvement or enhancement to an existing feature or task. LU-12998 DNE3: tunable to disable directory creation on MDT

          • Major - Major loss of function.
          • Reopened

          Improvement - An improvement or enhancement to an existing feature or task. LU-13417 DNE3: mkdir() automatically create remote directory on MDS which has more space

          • Major - Major loss of function.
          • Resolved

          Improvement - An improvement or enhancement to an existing feature or task. LU-10784 DNE3: mkdir() automatically create remote directory on MDS which has more space

          • Minor - Minor loss of function, or other problem where easy workaround is present.
          • Resolved

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              wc-triage WC Triage
              adilger Andreas Dilger
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              Dates

                Created:
                Updated: