[LU-10192] Agent entry for cross-MDTs reference

• Type: Technical task
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.11.0
• Assignee: nasf (Inactive)
• Reporter: nasf (Inactive)

Description

In DNE environment, the object and its name entry may reside on different MDTs. Under such case, we will create an agent entry under backend REMOTE_PARENT_DIR directory on the MDT where the object resides. The agent entry references the object locally. If without the agent entry, related object will be invisible for MDT side file level backup restore by userspace tool, such as 'tar'.

ldiskfs supports agent entry. After migrated to ZFS, the agent entry will be on ZFS backend. ZFS needs to handle it to avoid dangling.

On the other hand, there may be a lot of corss-MDTs reference for regular file. That may make the single REMOTE_PARENT_DIR very fat as to quite slow for being operated. So it is preferred to optimised that with multiple REMOTE_PARENT_DIRs, may be per MDT per REMOTE_PARENT_DIR.

Issue Links

• is related to: LU-11306 Moving files from one MDT to another does not free inodes on source MDT
• is related to: LU-10329 DNE3: REMOTE_PARENT_DIR scalability

Comments

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/29985/
Subject: LU-10192 lfsck: verify agent entry
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 83ed9453f0cd89057edae1aa4fa0de6007cf011c

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/29617/
Subject: LU-10192 osd-zfs: create agent entry for remote entry
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 5f3235b250cd952548344262db0d70d6134c66cb

[Gerrit Updater]

Oleg Drokin ([e-mail]) merged in patch https://review.whamcloud.com/29984/
Subject: LU-10192 osd-ldiskfs: create agent entry for remote entry
Project: fs/lustre-release
Branch: master
Current Patch Set:
Commit: 81a26d51b61646c067b27bd094ee2cf01ca13fdc

[Gerrit Updater]

Fan Yong ([e-mail]) uploaded a new patch: https://review.whamcloud.com/30075
Subject: LU-10192 test: debug patch for sanity-hsm test_406
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 3d9e1ecc1e7b65c7914e059a5d0a6948dae26f76

[nasf (Inactive)]

Another patch:
https://review.whamcloud.com/29617

[Gerrit Updater]

Fan Yong ([e-mail]) uploaded a new patch: https://review.whamcloud.com/29985
Subject: LU-10192 lfsck: verify agent entry
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 600e4251b33254b8fe54d592a8eb58472794bab0

[Gerrit Updater]

Fan Yong ([e-mail]) uploaded a new patch: https://review.whamcloud.com/29984
Subject: LU-10192 osd-ldiskfs: create agent entry for remote entry
Project: fs/lustre-release
Branch: master
Current Patch Set: 1
Commit: 2a4c25b6db3e68de8410010f5d812c99f5ac70c5