RE: Can't mount /home anymore

["Wolber, Richard C" <richard.c.wolber@xxxxxxxxxx>]

Before you do this, make double sure you have a backup of your disk volume. It can, and probably will, damage some or all of your filesystem.

 

First you need to find your backup superblocks. You can calculate them based on the filesystem block size, but I find that it's easier to just do the following:

 

[root@server ~]# dumpe2fs  /dev/sda6 | grep Backup
dumpe2fs 1.35 (28-Feb-2004)
  Backup superblock at 8193, Group descriptors at 8194-8194
  Backup superblock at 24577, Group descriptors at 24578-24578
  Backup superblock at 40961, Group descriptors at 40962-40962
  Backup superblock at 57345, Group descriptors at 57346-57346
  Backup superblock at 73729, Group descriptors at 73730-73730

 

Now that you have the backup superblocks, you have to replace the old superblock with a backup superblock:

 

e2fsck -b 8193 /dev/sda6

 

Then try to mount the filesystem. If it fails to mount, move on down to the next backup superblock (24577) and so on, until you run out of backup superblocks *OR* the filesystem mounts properly.

 

Once you get it mounted, recover whats left of your files to a safe place, wipe the drive, reformat it, restore your files and then think long and hard about getting a decent nightly backup solution in place!

 

..Chuck..

 

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From: Nickel Cadmium [mailto:nicdnicd@xxxxxxxxx]
Sent: Friday, February 02, 2007 7:14 AM
To: ext3-users@xxxxxxxxxx
Subject: Re: Can't mount /home anymore

Hi!

I'm still stuck with my unmountable home partition.
Would it be possible to mount it using a backup block somehow?

Cd

On 1/20/07, Nickel Cadmium <nicdnicd@xxxxxxxxx> wrote:

Hi Christian (& all)!

Thanks for the reply. I was away for some time but here is the extra information you requested.

Yes, after the message "fsck.ext3: e2fsck_read_bitmaps: illegal bitmap block(s) for /home", fsck just stops.
The command 'fsck.ext3 /dev/sda6; echo $?' returns the value 8. Looking at the man page for fsck, I found that this is an "Operational error". I have totally no clue what this means.

With fsck, nothing is reported in the syslog file. If I try mounting the partition, I get the following errors reported:
Jan 20 11:43:57 localhost kernel: EXT3-fs error (device sda6): ext3_check_descriptors: Inode bitmap for group 522 not in group (block 3271884801)!
Jan 20 11:43:57 localhost kernel: EXT3-fs: group descriptors corrupted !

I could dd the partition without errors. I did copy the partition two times already, I order to be able to try some recovery on it. With converting a copy to ext2 and running "fsck.ext2 -v -y" on it (in something like two days), I was able to get some files (all?) in the lost+found. However, the file names are lost and the directory structure as well. It's hard to tell which file is what.
I'm really wondering if there is a way to mount that partition again.

I run Mandriva on a Pentium PC. My kernel is 2.6.17-5mdv. However, I first thought than my /home problem was some kind of booting problem. Thus I upgraded from Mandriva 2006 to Mandriva 2007. This means that I don't know what my kernel was when the problem occurred. It should be 2.6.12 as this was a straight out-of-the-box installation.
My fsck version is "e2fsck 1.39".

Best wishes,
Cd

On 1/14/07, Christian Kujau <lists@xxxxxxxxxxxxxxx> wrote:

On Wed, 10 Jan 2007, Nickel Cadmium wrote:
> # fsck.ext3 /dev/sda6
> e2fsck 1.39 (29-May-2006)
> Group descriptors look bad... trying backup blocks...
> Inode bitmap for group 522 is not in group. (block 3271884801)
> Relocate<y>? yes
>
> fsck.ext3: e2fsck_read_bitmaps: illegal bitmap block(s) for /home

...and after this message, fsck.ext3 just stops? What's the exit code of
fsck.ext3? (e.g. 'fsck.ext3 /dev/sda6; echo $?'). Try " fsck.ext3 -v" for
more details. Is there anything related in your syslog? Can you dd(1)
the device (read! not write! :)) without errors?

Which kernel/arch are you running?

Christian.
--
BOFH excuse #99:

SIMM crosstalk.

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