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Re: bad superblock after lvextend

To: Nathan Scott <nathans@xxxxxxx>
Subject: Re: bad superblock after lvextend
From: "Frank J. Buchholz" <frankb@xxxxxxxxx>
Date: Mon, 22 Nov 2004 21:01:09 -0500
Cc: linux-xfs@xxxxxxxxxxx
In-reply-to: <20041123002224.GC695@frodo>
References: <41A2837C.4080203@xxxxxxxxx> <20041123002224.GC695@frodo>
Sender: linux-xfs-bounce@xxxxxxxxxxx
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Nathan Scott wrote:

On Mon, Nov 22, 2004 at 07:25:32PM -0500, Frank J. Buchholz wrote:
Hello,

I recently attempted to extend my logical volume. First I added an additional physical volume to an existing volume group. This worked fine.

vgextend Volume00 /dev/sba

However when it came time to run the lvextend command I received a number of device-mapper errors.

lvm> lvextend -L+1G /dev/Volume00/LogVol00
Extending logical volume LogVol00 to 2.93 TB
device-mapper ioctl cmd 9 failed: Invalid argument
Couldn't load device 'Volume00-LogVol00'.
Problem reactivating LogVol00

While I was trying to determine what the errors were I noticed that the filesystem that sits on the logical volume being extended was no longer available. I attempted to umount the filesystem however the command froze. I then rebooted the system without mounting the filesystem in question and manually mounted the filesystem. XFS reported back that it could not locate the superblock.

I then ran xfs_repair...
# xfs_repair /dev/Volume00/LogVol00
Phase 1 - find and verify superblock...
superblock read failed, offset 0, size 524288, ag 0, rval 0

fatal error -- Invalid argument

Is it possible to repair this problem either through LVM or XFS? I

Does od report "XFSB" at the start of the device?

# od -c /dev/Volume00/LogVol00 -N 4
0000000   X   F   S   B
0000004
#
If not, your logical volume is seriously messed up and
you'll need to fix things up inside LVM before you go
anywhere near the device with xfs_repair.

noticed there are a number of achieved .vg files in /etc/lvm/archive, is it possible to restore LVM from one of these? Or is it possible to rebuild the superblock?

Sounds like either user error, or something went wrong
inside LVM?

cheers.

Hi Nathan,

Running the command produces the following result.
# od -c /dev/Volume00/LogVol00 -N 4
0000000
#

Looks like I'm in bad shape.
I now realize how I created this problem, I just don't know how to fix it.

I mistakingly added /dev/sba as the physical volume to a volume group that contained /dev/sba1, the one partition on sba. These are essentially one in the same. So when I executed the lvextend command device-mapper had an error. I'm honestly surprised it did anything, especially write over the superblock.

Any direction on how I can recover from within LVM? I never was able to execute the xfs_grow so I'm hoping the data in the filesystem still exists.

Thanks,
Frank

Hmm, I knew I shouldn't have left SGI.


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