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  1. Lustre
  2. LU-14692

deprecate use of OST FID SEQ 0 for MDT0000

Details

    • 9223372036854775807

    Description

      Since Lustre 2.4.0 and DNE1, it has been possible to create OST objects using a different FID SEQ range for each MDT, to avoid contention during MDT object precreation.

      Objects that are created by MDT0000 are put into FID SEQ 0 (O/0/d*) on all OSTs and have a filename that is the decimal FID OID in ASCII. However, SEQ=0 objects are remapped to IDIF FID SEQ (0x100000000 | (ost_idx << 16)) so that they are unique across all OSTs.

      Objects that are created by other MDTs (or MDT0000 after 2^48 objects are created in SEQ 0) use a unique SEQ in the FID_SEQ_NORMAL range (> 0x200000400), and use a filename that is the hexadecimal FID OID in ASCII.

      For compatibility with pre-DNE MDTs and OSTs, the use of SEQ=0 by MDT0000 was kept until now, but there has not been a reason to keep this compatibility for new filesystems. It would be better to have MDT0000 assigned a "regular" FID SEQ range at startup, so that the SEQ=0 compatibility can eventually be removed. That would ensure OST objects have "proper and unique" FIDs, and avoid the complexity of mapping between the old SEQ=0 48-bit OID values and the IDIF FIDs.

      Older filesystems using SEQ=0 would eventually delete old objects in this range and/or could be forced to migrate to using new objects to clean up the remaining usage, if necessary.

      Attachments

        1. serial.txt
          778 kB
        2. stdout.txt
          484 kB

        Issue Links

          Activity

            [LU-14692] deprecate use of OST FID SEQ 0 for MDT0000
            adilger Andreas Dilger made changes -
            Labels Original: medium New: medium scalability
            adilger Andreas Dilger made changes -
            Link Original: This issue is related to LU-18311 [ LU-18311 ]
            adilger Andreas Dilger made changes -
            Link New: This issue is related to LU-18311 [ LU-18311 ]
            adilger Andreas Dilger made changes -
            Link New: This issue is duplicated by EX-8285 [ EX-8285 ]
            pjones Peter Jones made changes -
            Fix Version/s New: Lustre 2.15.3 [ 15998 ]
            eaujames Etienne Aujames made changes -
            Link New: This issue is related to LU-16692 [ LU-16692 ]
            bzzz Alex Zhuravlev made changes -
            Attachment New: stdout.txt [ 48544 ]
            Attachment New: serial.txt [ 48545 ]
            pjones Peter Jones made changes -
            Resolution New: Fixed [ 1 ]
            Status Original: Open [ 1 ] New: Resolved [ 5 ]
            adilger Andreas Dilger made changes -
            Link New: This issue is blocking EX-1053 [ EX-1053 ]
            adilger Andreas Dilger made changes -
            Link New: This issue is related to LU-9054 [ LU-9054 ]

            People

              dongyang Dongyang Li
              adilger Andreas Dilger
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              Dates

                Created:
                Updated:
                Resolved: