Re: My superblock has been destroyed - please help!

[Stephan Hachinger <sharcor@gmx.de>]

On Fri, 31 Aug 2001 17:33:51 -0400
ajlewis2@intac.com wrote:

> In linux.debian.user, you wrote:
> > Hello!
> > 
> > Hmm, the subject says almost everything... my almost new (!) IBM
hard disk
> > suddenly had some bad sectors and one was the superblock of my
linux
> > partition. So, I cannot boot into linux any more, and if I try to
e2fsck
> > the partition, e2fsck doesn't find the superblock. Also, if I try
with -b
> > 8193 or -b 16385, e2fsck says that these blocks contain a "bad
magic
> > number". Hmm, I've read that these blocks should actually be
superblock
> > backups but I think since my fs was made with the new default
> > "sparse_superblocks" option, the backups are perhaps somewhere
else. Can
> > anyone please help me with this issue? I just desperately want to
rescue
> > my data before I send the drive back to IBM or so because they
will
> > probably send me a new HDD but not my old data, and of course I
have not
> > made backups, stupid me. The partition is /dev/hda2 and about 7.7
GB. I
> > also have a possibility to temporarely store up to 12 GB of data
on hda1,
> > a fat32 partition which scandisk could obviously "stabilize" more
or less
> > after a bad block marking. At the moment, I'm trying to dd
/dev/hda2 into
> > a file on /dev/hda1 but there seems to be a problem with the
maximal file
> > size on fat partitions (does anyone know about that?).
> > 
> > Regards and thanks in advance,
> > 
> > Stephan
> > 
> 
> This is from the e2fsck manpage:
> 
>               The location of the backup superblock is dependent on
the
>               filesystem's blocksize.  For filesystems with 1k
blocksizes, a
>               backup superblock can be found at block 8193; for
filesystems
>               with 2k blocksizes, at block 16384; and for 4k
blocksizes, at
>               block 32768.
> 
>               Additional  backup superblocks can be determined by
using the
>               mke2fs program using the -n option to print out where
the
>               superblocks were created.  The -b option to mke2fs,
which
>               specifies blocksize of the filesystem must be
specified in
>               order for the superblock locations that are printed
out to be
>               accurate.

Yeah, this was exactly what I needed! Now I have the offsets of my
superblocks and I'm running e2fsck at the moment. Thanks very much,

Stephan