[LU-3335] LFSCK II: MDT-OST OST local consistency checking

• Type: New Feature
• Resolution: Fixed
• Priority: Critical
• Fix Version/s: Lustre 2.5.0, Lustre 2.6.0
• Affects Version/s: Lustre 2.5.0
• Labels: LFSCK
• Story Points: 89

Epic

layout

• Assignee: nasf (Inactive)
• Reporter: Andreas Dilger

Description

This ticket is related to running the existing OI Scrub checking for OST OSD devices. This includes

• running the object iterator (should already work)
• rebuilding the OI (O/$seq/d*/$oid for OST objects
• rebuilding the O/$seq/LAST_ID file if incorrect (LU-14)

Issue Links

• duplicates: LU-3995 CLONE - LFSCK II: MDT-OST OST local consistency checking
• is blocking: LU-1267 LFSCK II: MDT-OST consistency check/repair
• is related to: LU-14864 osd_fid_lookup() ASSERTION( !updated ) failed
• is related to: LU-4829 LBUG: ASSERTION( !fid_is_idif(fid) )
• is related to: LU-3588 use lctl --device option to specify device for LFSCK

Comments

[nasf (Inactive)]

OI table based scanning to repair the inconsistency of inode without LMA (or dummy OI mapping items) will be an time-consuming work. Just like find out orphan OST-objects for LFSCK phase II, we can consider to do that in later release. Instead, I made another relative simple patch to resolve part of the issues: only the used/accessed objects will be repaired by the RPC service threads.

http://review.whamcloud.com/#/c/6899/

Andreas, how do you think?

[nasf (Inactive)]

The patches list:

http://review.whamcloud.com/#/c/6697/
http://review.whamcloud.com/#/c/6669/
http://review.whamcloud.com/#/c/6698/
http://review.whamcloud.com/#/c/6857/
http://review.whamcloud.com/#/c/7143/
http://review.whamcloud.com/#/c/7144/
http://review.whamcloud.com/#/c/7145/

[Andreas Dilger]

By "users of OI Scrub" I mean "users of the object iterator".

I also don't think it is harmful to update LAST_ID under lock, if this is done with proper locking of the LAST_ID object. Since this is now just a normal FID, we should be able to use the object lock to serialize access?

[Alex Zhuravlev]

hmm, I'm not aware of any users of OI Scrub - it's all internal to OSD ?
at which point you want to update LAST_ID? I guess this can't be done any time, OFD might overwrite it immediately?

[Andreas Dilger]

Sure, the users of OI Scrub will just iterate over the inodes and get the object FIDs from LMA or filter_fid (in case of upgraded filesystems. However, if OST objects are located in lost+found due to filesystem corruption, then they need to be moved back to /O/$seq/d*/$oid (i.e. restored to the "OI" for the OST). This is currently handled by a separate ll_recover_lost_found_objs tool, but it would be better to avoid the need to mount and run this separately on the OST.

[Alex Zhuravlev]

in the past I asked few times that OI scrub should be independent from specific OI format whether it's oi.* files or /O hierarchy. the logic of OI scrubber should just use osd_oi_lookup(), osd_oi_delete() and osd_oi_insert() and leave osd_oi_*() functions to decide which mapping to use for a specific object.