Re: ext3 filesystem: superblock not found

[johannes <johannes121@gmx.de>]

johannes wrote:
> I somehow broke the data partition of my server when preparing for 
> backup. e2fsck can't find superblock, but finds 'bad magic number...'
>
> ---output of e2fsck:
> srv:/var/log# e2fsck /dev/rd/c0d0p3
> e2fsck 1.37 (21-Mar-2005)
> Couldn't find ext2 superblock, trying backup blocks...
> e2fsck: Bad magic number in super-block while trying to open /dev/rd/c0d0p3
>
> The superblock could not be read or does not describe a correct ext2
> filesystem.  If the device is valid and it really contains an ext2
> filesystem (and not swap or ufs or something else), then the superblock
> is corrupt, and you might try running e2fsck with an alternate superblock:
>     e2fsck -b 8193 <device>
>
>
> ---/var/log/syslog------------------
>
> Dec  2 19:39:10 srv kernel: EXT3-fs error (device rd/c0d0p3): 
> ext3_readdir: bad entry in directory #2: inode out of bounds - offset=0, 
> inode=2, rec_len=12, name_len=1
> Dec  2 19:39:10 srv kernel: Aborting journal on device rd/c0d0p3.
> Dec  2 19:39:10 srv kernel: ext3_abort called.
> Dec  2 19:39:10 srv kernel: EXT3-fs abort (device rd/c0d0p3): 
> ext3_journal_start: Detected aborted journal
> Dec  2 19:39:10 srv kernel: Remounting filesystem read-only
> Dec  2 19:39:10 srv kernel: EXT3-fs error (device rd/c0d0p3): 
> ext3_readdir: bad entry in directory #2: inode out of bounds - offset=0, 
> inode=2, rec_len=12, name_len=1

I just reformatted the partition.

I tried to
mke2fs -S /dev/rd/c0d0p3
followed by
e2fsck -f /dev/rd/c0d0p3
but it didn't work.

Is there any way to find out what went wrong and why the superblock 
could not be recovered. It would just be comforting to know how 
something like this can be avoided in future.

Thanks for any help.

Johannes