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

• Type: Technical task
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.14.0
• Assignee: Mikhail Pershin
• Reporter: Mikhail Pershin

Description

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.

Comments

[Peter Jones]

Landed for 2.14

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/38152/
Subject: LU-13415 dom: use DoM optimization for DOM+OST files
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 067dc642521487b2d53f46da1dec4b9d5f570c67

[Gerrit Updater]

Mike Pershin ([e-mail]) uploaded a new patch: https://review.whamcloud.com/38152
Subject: LU-13415 dom: use DoM optimization for DOM+OST files
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 498337e19e62a3d7fea5eb2f2835f41284ccb663