[LU-11190] LSOM size/age accounting histogram Created: 29/Jul/18  Updated: 24/Apr/20

Status: Open
Project: Lustre
Component/s: None
Affects Version/s: Lustre 2.12.0
Fix Version/s: None

Type: Improvement Priority: Minor
Reporter: Andreas Dilger Assignee: WC Triage
Resolution: Unresolved Votes: 0
Labels: None

Issue Links:
Related
is related to LU-9538 Size on MDT with guarantee of eventua... Resolved
is related to LU-12026 verify that MDS stores atime/mtime/ct... Resolved
is related to LU-13484 inode access time tables Open
Rank (Obsolete): 9223372036854775807

 Description   

With LSOM data being available on the MDT, it would be possible to automatically create a histogram of file sizes on the MDT. This would be useful for things like DoM planning, and other performance planning.

As each file's size is recorded, a counter in the matching power-of-two histogram bucket would be incremented, and a flag set in the LMA xattr. When a file with the LMA flag is deleted or the LSOM size is changed to a new bucket, the appropriate histogram bucket would be decremented.

It would be possible to do the same with other inode attributes (e.g. atime/mtime/ctime age histogram).

The question would be how useful it is to keep these metrics updated on every inode update vs. scanning periodically (e.g. daily or weekly) to get the information only when it is needed.

User/Group/Project quota can already track UID/GID/PRJID inode and space usage distribution.


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