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Date: Tue, 23 Oct 2007 02:08:20 +0100
From: Alasdair G Kergon <agk@redhat.com>
Subject: Re: [linux-lvm] lvreduce
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To: LVM general discussion and development <linux-lvm@redhat.com>

On Mon, Oct 22, 2007 at 08:36:26PM -0400, Stuart D. Gathman wrote:
> On Mon, 22 Oct 2007, Humble Chirammal wrote:
> >   One of the customer ran  "lvreduce" command without reducing the 
> > filesystem (resize2fs ).  After the system was rebooted got this error.
> > <<snip>>
> > The filesystem size (according to the superblock) is 19922944 blocks
> > The physical size of the device is 13369344 blocks
> > Either the superblock or the partition table is likely to be corrupt!
> >  <<snip>>
> > Is there any way for data recovery???
> Stop them from doing anymore LVM operations until recovery.
> If nothing else has been done, undo the lvreduce with vgrestore.
> LVM keeps backup versions of the metadata (/etc/lvm/archive on my
> system).  I'll let the experts provide the exact syntax.  I haven't
> had to do it yet :-)
> If they have used the freed extents (lvextend or lvcreate or ...),
> then they are hosed.
 
Indeed - as long as they made no other changes, 'vgcfgrestore' will undo the
lvreduce operation.  You can use '-ll' to check.

If they're using X, suggest trying the GUI (packages system-config-lvm)
interface to carry out resizing.

Alasdair
-- 
agk@redhat.com