botched RAID, now e2fsck or what?

[Christian Kujau]

On Wed, 9 Dec 2009 at 20:50, Lucian Șandor wrote:
> However, no combination seems useful. Sometimes I get:
> "e2fsck: Bad magic number in super-block while trying to open /dev/md0"

Did you try specifying a different superblock? If you can remember how the 
filesystem was initially created, you can use:

 $ mkfs.ext3 -n /dev/md0        (MIND THE -n SWITCH!)

to get a list of the backup superblocks, which you can then use with fsck. 
Don't forget to man mkfs.ext3 :-)

> Question 1: Is there a way to make dumpe2fs or another command
> estimate the number of files in what appears to be an ext3 partition?

I can only think of:

$ dumpe2fs -h /dev/loop0 | egrep 'Inode count|Free inodes'

The difference between both values should be the used inodes, i.e. 
files/directories on the filesystem.

> Question: if I were to struck lucky and find the right combination,
> would dumpe2fs give me a very-very long list of superblocks?

The superblock count depends on how the fs was initially created. I could 
imagine that the list is longer for a real filesystem, as "garbage" 
won't have any superblocks at all.

> superblocks extend far into the partition, or do they always stop

Superblocks are usually spread all over the device.

> Question 3: Is there any other tool that would search for files in the
> remains of an ext3 partition, and, this way, validate or invalidate
> the permutations I try?

Have a look at:
http://ext4.wiki.kernel.org/index.php/Undeletion

Christian.
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