dump/restore corrupted filesystems

Roland Smith rsmith at xs4all.nl
Mon Apr 16 17:08:31 UTC 2007

On Mon, Apr 16, 2007 at 09:11:48AM -0500, CyberLeo Kitsana wrote:
> I have a 1.2TB UFS2 filesystem with irrecoverable corruption. As such, I
> must move all 500GB or so of data off of it and re-newfs it.

If the corruption is due to hardware failure, your data is probably lost.

Ditto if the corruption is so bad that fsck_ffs can't handle it. You can
e.g. tell fsck_ffs(8) to use a backup superblock, with the -b option.

> Does anybody know whether dump/restore can gracefully handle filesystem
> corruption, or will it happily back up and restore said damage to the
> pristine filesystem?

Dump examines the filesystem to see which files need to be backed up. So
dumping a corrupted FS will probably not produce the desired results. If
it did, we wouldn't need backups.

What you could do is use dd(1) with nc(1) to send a copy of the raw
device data to another machine, and try if you can pry your data from that.

R.F.Smith                                   http://www.xs4all.nl/~rsmith/
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