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  1. Lustre
  2. LU-9309

Add 64-bit inode number support


    • Type: New Feature
    • Status: Open
    • Priority: Major
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: None
    • Labels:
    • Rank (Obsolete):


      With current hardware clusters faced with the trouble of creating enough inodes on LDISKFS partitions. MDS has 0-size files to store some information about Lustre FS files. Current MDS disk sizes allow to store large amount of such files, but EXT4 limits this number to ~4 billions.
      Lustre FS has features like DNE to distribute MDS over many targets (disks), but disks are used not effectively. It would be great to have ability to store more then ~4 billions inodes on one EXT4 file system.

      This topic ("64-bit inode number") recently was discussed in ext4 list. The resume is:

      There are two possible solutions:
      1. Store higher 32 bit of inode number in ext4 dirent
      2. New feature flag which defines the use a 64-bit inode number

      Andreas Dilger gave strong reasons to use 1st solution:

      The reasons are:

      • this won't use more space for 64-bit inodes than ext4_dir_entry64
      • for 32-bit inode numbers will have smaller dirents
      • significantly more 32-bit dirents can fit into a leaf block (i.e. 10-25%)
      • it is backwards compatible with existing directories and can transparently store 64-bit inode numbers into 32-bit directories without a full update
      • it avoids duplicate code paths for ext4_dir_entry vs ext4_dir_entry64
      • it would be possible to only store high 16 bits (2^48 inodes) since this may be enough for ext4, since ext4_extent can only address 2^48 blocks (2^60 bytes) and there isn't much value to more inodes than blocks?

      This issue is about using dirdata to store high bits of 64bit inode number.


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              • Assignee:
                artem_blagodarenko Artem Blagodarenko
                artem_blagodarenko Artem Blagodarenko
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                • Created: