[lustre-discuss] problem after upgrading 2.10.4 to 2.12.4

[Hebenstreit, Michael]

We experienced on our Archive Lustre (ZFS based, 4 OST servers with 6 OSTs pools each) the very same issues as described here:
https://jira.whamcloud.com/browse/LU-13392
Certain directories cannot be accessed, and the OSTs shows thousands of errors "Can't find FID Sequence". Unfortunately I cannot even start the recommended file system checking on the OST devices  - example:
[root at elfsa2o1 ~]# lctl lfsck_start -o -M lfsarc02-OST0002
Fail to start LFSCK: Operation not permitted
[root at elfsa2o1 ~]# lctl lfsck_start -M lfsarc02-OST0002
Fail to start LFSCK: Operation not supported
On a similar system that was first installed as 2.10.4, then upgraded to 2.10.8, and now is also running on 2.12.4, at least the second command starts:
# lctl lfsck_start -M lfsarc01-OST0002
The commands are issued on the system with the actual ZFS pools running.

Questions:
Is there any way to force the file system checks?
Has anyone found a workaround for the FID sequence errors?
Can I downgrade from 2.12.4 to 2.10.8 without destroying the FS?
Has the error described in https://jira.whamcloud.com/browse/LU-13392 been fixed in 2.12.5<https://jira.whamcloud.com/browse/LU-13392%20been%20fixed%20in%202.12.5>?

Thanks
Michael


------------------------------------------------------------------------
Michael Hebenstreit                 Senior Cluster Architect
Intel Corporation, MS: RR1-105/H14  TSACG
1600 Rio Rancho Blvd SE             Tel.:   +1 505-794-3144
Rio Rancho, NM 87124
UNITED STATES                       E-mail: michael.hebenstreit at intel.com<mailto:michael.hebenstreit at intel.com>


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