Subj : Re: e2fs corrupted superblock
To   : comp.os.linux
From : Thomas D. Shepard
Date : Thu Jul 29 2004 10:56 pm

On Sun, 11 Jul 2004 16:28:12 -0700, pandora_xero wrote:

> 
> Richard Huelbig wrote:
>> Pandora,
>>
>> Here's a Google hit on what I think you need. Check the -b option
> where
>> you specify an alternate superblock.
>>
>> http://www.netadmintools.com/html/8e2fsck.man.html
>>
>> Hope this helps.
>>
>> Regards,
>>
>> Richard Huelbig
> 
> o...k.... after doing all this i have come to the realization that i
> am, indeed, screwed. i can't even read the backup superblocks. unless
> there's a way of accessing the drive without using a superblock
> (there's none that i'm aware of), i'm screwed.

Of course you can access the drive without using a superblock. Check out
the documentation for the "dd" command. If you know the locations of the
backup superblocks, you can examine each of them with dd. You can also
overwrite the bad one with dd, which will fix your problem, provided there
is nothing else corrupted that you haven't found yet. (The bad one is
probably the first one. It will be different than all the others.)

If you don't know the locations of the superblocks, you may be able to
guess them. Check the documentation for whatever command you would use to
format the type of filesystem that is on that drive (mke2fs for and ext2
file system). You will probably find a way to run that command in a
"do-nothing" mode that merely prints out what it would have done had you
formatted with it (mke2fs does). It will tell you where it would have
written the superblocks. If you are lucky enough to guess the same options
that were specified when the partition was originally formatted, the
superblock locations will be correct. (Taking defaults for everything
would be my first guess. My second guess would be defaults for everything
but 0% for the fraction of space reserved for the superuser.)

Also, assuming you have some place big enough to hold all the data, you
can use "dd" to make a backup copy of the entire drive before you start
fooling around with it.

-- 
Thomas D. Shepard
Sorry, you can't email me.
(Email address is fake.)

.