Superblock missing, FS corruption after power outage

Andreas Dilger adilger at
Tue Apr 21 12:01:30 UTC 2009

On Apr 21, 2009  19:17 +1000, Robert Davidson wrote:
> It is possible in this case that a fair chunk of data could have been lost as
> the RAID card has a 256mb cache with no battery backup for cached data,

At this point, all bets are off - ext3+jbd expects when the disk reports
that data is safe on disk that it really is safe.

> seems somewhat extreme that the superblock went missing (according to mount
> the filesystem didn't exist, according to fsck.ext3 it had to use a backup
> superblock), and that a whole directory disappeared and didn't end up in
> lost+found.

Well, if you lost 256MB at the start of the filesystem then that could easily
contain the whole directory, which might only be a few blocks in size.

Cheers, Andreas
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.

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