On 11/19/12 2:32 AM, George Spelvin wrote:
...

"e2fsck -n" will only print errors and not change anything.  It's
always safe.

Try "e2fsck -n -v /dev/md0" (given the dumpe2fs failure, I expect that
will not work) and then try "e2fsck -n -v -b 32768 /dev/md0".

I don't know what happened to your superblock, but if that's all that
got trashed, recovery is actually quite straightforward and there's no
risk of data loss.  e2fsck will just print a huge number of "free blocks
count wrong" messages as it fixes them.

(However, that's a pretty big "if".)


Another thing that would be useful is "dd if=/dev/md0 skip=2 count=2 | xxd"
(or od -x if you don't have xxd).  That will give a hex dump of the
primary superblock, which might show the extent of the damage.


If "e2fsck -n -b 32768" works, the way to repair it is to run it again
without the "-n", but the -n output will say how bad it is.

Whoops, I replied without seeing these other replies; somehow threading
was broken w/ George's first reply.

Anyway - I would not go to e2fsck yet.  I think your raid is mis-assembled.
I'd investigate that first.  I'll look at the other output a bit more, but
for now, I'd stay away from fsck - just wanted to get that out there quick.

-Eric