[Lustre-discuss] Solved: incorrect num_osts; LBUG
Michael Sternberg
sternberg at anl.gov
Sun Jan 4 12:25:08 PST 2009
I wrote:
On Jan 2, 2009, at 19:24 , Michael Sternberg wrote:
> While performing an LFSCK after upgrade lustre-1.6.6, the MDS claims
> to have 512 OSTs [while there is only 1]:
>
> MDS: num_osts = 512
Well, I found an interesting section "How to fix bad LAST_ID on an
OST" in the operations manual, Appendix D, which pointed more or less
in the right direction.
Briefly, /lov_objid within the MDS ldiskfs is constructed from /O/0/
LAST_ID in all the OSTs' ldiskfs. In my case, with only one OST, the
first and only entry agrees between these two files, and the rest of
lov_objid was padded with NULs to 4KB (block size?). I do not
understand what caused this, but, given prior e2fsck output indicating
length 8, I decided to simply chop off the NULs, which indeed made
e2fsck happy. lfsck on a client found a handful of empty orphans, but
a backup on the client side still matches the contents of the rest of
the fs (phew!).
Regards, Michael
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