dump/restore corrupted filesystems

[Roland Smith]

On Mon, Apr 16, 2007 at 11:14:35PM -0500, CyberLeo Kitsana wrote:
> Roland Smith wrote:
> > 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.
> 
> Sorry if I wasn't clear. Most all of the data is readable and complete
> if I mount the filesystem read-only. It just panics the box when mounted
> read/write, and fsck can't fix the damage.

That might be worth filing a PR for, especially the panics. 

Exactly what is damaged?  Garbage in files? Wrong inode counts? I've had
unclean filesystems because of panics, but nothing fsck_ffs couldn't
fix.

You might want to check the hardware too. Use smartmontools in case of
(S)ATA drives.

> My question was more along the lines of whether or not dump/restore
> would see that those corrupted directory and file inodes were indeed
> corrupt and not bother attempting to back them up, or if it would
> happily back them up and restore them in their corrupted state to a new
> filesystem, thus trashing it.

Looking at /usr/src/sbin/dump/traverse.c, dump traverses the used inodes
list and all directories. So if any of these is corrupt, your dump will
be too. And if the contents of the inodes is corrupted, so will the dump. 

> Ironically, this is the machine that holds the backups.

Oops.

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