[LU-13415] DoM: keep optimizations even when OST stripe is initialized

Thu, 14 May 2020 16:25:45 +0000

Some DoM optimizations like read-on-open or IO-lock-on-open are being used only when OST stripes are non-initialized, supposing that it makes a little sense otherwise. Meanwhile, OST stripe can be initialized by a first append to the DOM file, so that is not good indicator to stop using DOM benefits. File can stay small and with just MDT stripe used for a long time after that. Ideally that would be to stop using DoM only when OST objects have non-zero size but that is not easy to figure out from MDT.
Nevertheless, it is not big deal to use read-on-open and IO-lock-at-open features even for files with OST data with few extra checks, e.g. don't use read-on-open if MDT stripe is full and take IO lock at open optionally in 'try' mode.

Whamcloud Community JIRA

[LU-13415] DoM: keep optimizations even when OST stripe is initialized