Recovering Trashed Filesystems

[Roland Smith]

On Thu, Jul 30, 2009 at 11:46:50PM -0700, Crist J. Clark wrote:
> I have two file systems in very sad shape that I would like
> to retrieve some files from. I've net booted the sick box
> and can access the two bad UFSs. One file system, the root
> file system, isn't too bad off. However, the usr directory
> is messed up.
<snip>
> Now I can "mount -r /dev/ad0s1a /mnt" to get the above results,
> but "fsck /dev/ad0s1a" returns,
> 
>   # fsck /dev/ad0s1a
>   ** /dev/ad0s1a
>   BAD SUPER BLOCK: VALUES IN SUPER BLOCK DISAGREE WITH THOSE IN FIRST ALTERNATE
> 
>   LOOK FOR ALTERNATE SUPERBLOCKS? [yn] y
> 
>   32 is not a file system superblock
>   SEARCH FOR ALTERNATE SUPER-BLOCK FAILED. YOU MUST USE THE
>   -b OPTION TO FSCK TO SPECIFY THE LOCATION OF AN ALTERNATE
>   SUPER-BLOCK TO SUPPLY NEEDED INFORMATION; SEE fsck(8).

Try 'fsck_ffs -b 160 /dev/ad0s1a' assuming you're using a UFS2 filesystem.
If that doesn't work, try adding the '-D' flag, but heed the warning in
fsck_ffs(8). Only run fsck_ffs when the filesystem is not mounted!

If you can, make a copy of the damaged fs and save it to another disk or
another machine. Then try to repair the copy. If it fails, you haven't
lost your original data.

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