Hi,

I am a graduate student and recently, one of the two 3ware Escalade
7500-8 cards in our filserver bonked out. We got a replacement but it
seems that the previous card corrupted the filesystem somehow. Now I
cannot mount/e2fsck one of the two RAID arrays.
Luckily the root partition RAID is alive and working. But the other
RAID absolutely needs to be recovered. It has 600GB of not completely
backed up data.
I have tried the obvious solutions already:
1. e2fsck : does not work -> cannot find superblock
2. e2fsck -b with ALL alternate superblocks: does not work

The errors are as follows:

e2fsck 1.27 (8-Mar-2002)
Couldn't find ext2 superblock, trying backup blocks...
fsck.ext3: Filesystem has unexpected block size while trying to open /dev/sdb1

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>

I have not tried mke2fs -S yet as that is supposed to be
destructive. Also I have not yet tried data recovery tools like
e2retrieve, e2restore or debugfs.
The situation is pretty much desperate and my advisor is willing to
throw in a printer or playstation as a reward to whosoever helps us
get the filesystem back.

Any *quick* help would be really appreciated.

"Puneet Gupta" <puneet@steiner.ucsd.edu> wrote in message
news:wrk753u4x9.fsf@steiner.ucsd.edu...
> Hi,
>
> I am a graduate student and recently, one of the two 3ware Escalade
> 7500-8 cards in our filserver bonked out. We got a replacement but it
> seems that the previous card corrupted the filesystem somehow. Now I
> cannot mount/e2fsck one of the two RAID arrays.
> Luckily the root partition RAID is alive and working. But the other
> RAID absolutely needs to be recovered. It has 600GB of not completely
> backed up data.
> I have tried the obvious solutions already:
> 1. e2fsck : does not work -> cannot find superblock
> 2. e2fsck -b with ALL alternate superblocks: does not work
>
> The errors are as follows:
>
> e2fsck 1.27 (8-Mar-2002)
> Couldn't find ext2 superblock, trying backup blocks...
> fsck.ext3: Filesystem has unexpected block size while trying to open
/dev/sdb1
>
> 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>


Ah, well 8193 is probably not going to be correct on such a large filesystem


e2fsck -b 16385 <device>

e2fsck -b 2^N + 1 , where N is integer from 13 and on.

Its nondestructive to try, if it can find a backup superblock, it can
replace the superblock and continue.

After that, you are into trying to recreate a superblock ...

which should be able to done... its just a bunch of info about the size of
the filesystem and where various info is on that filesystem , as chosen by
mke2fs ...

You could try to use mke2fs in 'no write' mode (get the source and stop it
writing ? )
and point it at the system, and get it to make a superblock ... this
superblock should then work.
To test a superblock, dont use e2fsck, use mount in read only mode,
'mount -o ro /dev/blah /mnt/blah ' )