[LU-11190] LSOM size/age accounting histogram

Related — Fri, 24 Apr 2020 00:54:17 +0000

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.

Whamcloud Community JIRA

[LU-11190] LSOM size/age accounting histogram