[LU-4610] LFSCK needs to log all changes and errors found

• Type: Technical task
• Resolution: Fixed
• Priority: Critical
• Fix Version/s: Lustre 2.6.0
• Affects Version/s: Lustre 2.6.0
• Assignee: nasf (Inactive)
• Reporter: Andreas Dilger

Description

LFSCK needs to log with D_LFSCK all fixes that it makes and any inconsistencies that it finds that it does not repair (e.g. unknown LOV magic layouts). Otherwise it will be making secret changes to the filesystem and when there are problems they will be impossible to debug.

Also, if LFSCK is fining inconsistencies in the filesystem it is important for administrators and developers to know this in case they are being caused by bugs in the Lustre code or due to hardware or other problems.

I think logging inconsistencies (whether repaired or not) via D_LFSCK is the best way to do this. It would be useful to have a common format for such messages, so they could be parsed later to generate pathnames from the FIDs in the log messages. We should avoid pruning D_LFSCK messages that are not related to problems in the filesystem, except for limited start and stop messages. It might be necessary to quiet messages about adding individual FIDs to the OI file if the file was removed, since that will be too many messages on a large filesystem.

The D_LFSCK flag should be added to the default flags that are enabled all the time, since this should not normally generate any log messages on a correct filesystem (except limited start/stop messages).

Issue Links

• is related to: LU-5202 LFSCK 5: LFSCK needs to log all changes and errors found

Comments

[Andreas Dilger]

Still one patch to land to turn the LFSCK debugging on by default.

[James Nunez (Inactive)]

Patch to turn on LFSCK debug messages in our test infrastructure is at: http://review.whamcloud.com/#/c/10814

[Peter Jones]

Landed for 2.6

[nasf (Inactive)]

I have enhanced the patch http://review.whamcloud.com/#/c/10579/ to add more D_LFSCK message for LFSCK check/repair, and enable D_LFSCK by default for tests.

[Andreas Dilger]

I think it also makes sense to enable D_LFSCK logging by default, once noisy messages are quieted (in patch 10579).

[nasf (Inactive)]

Since then, I prefer to split the work into two parts:

1) The first part will add/remove/change the D_LFSCK debug log in master, and the users can dump the LFSCK log via "lctl debug_kernel". Such patch should be landed to Lustre-2.6

2) The second part will implement some mechanism to start/stop/filter/collect the LFSCK logs automatically. Such patch will be landed to Lustre-2.7 or later.