lvm2 problem

[Chris Tyler]

On Mon, 2008-09-22 at 12:31 -0400, Chris Snook wrote:
> Bogdan Sarandan wrote:
> > Hello,
> > 
> > 
> > I want to know if there is any way to recover data from a damage lvm2
> > partition. The case is like this. We had a fedora core 7 server and i ran the
> > command fsck when the disk was mounted and running. I was not able to boot
> > the disk anymore after I typed fsck. Now that disk is in another computer
> > running linux. I am not able to mount that partition anymore. The error is
> > like this:
> > 
> > rds:/ # mount /dev/sdb2 /mnt/sdb2 mount: unknown filesystem type
> > 'LVM2_member'
> > 
> > Can you please tell me a way to recover my data from that lvm2 type partition
> > ?
> > 
> > Thanks,
> > 
> 
> You need to add it to an LVM2 volume group, and then fsck the logical volume. 
> Your best chance is to use a backup superblock (see man e2fsck) but if the fsck 
> completed, it's probably wiped out.
> 
> -- Chris
> 

The specific commands you need are vgscan and vgchange; access to the
logical volume will be through /dev/mapper/yourVGname-yourLVname
(or /dev/yourVGname/yourLVname) and not /dev/sdb* (which is the raw
partition containing a PV).

(Although the context is different, there are some examples of
vgscan/vgchange usage here:
http://dailypackage.fedorabook.com/index.php?/archives/159-.html )

-Chris