[SOLVED] Is there any way to restore deleted LVM2 volumes?

piratesmack · 06-12-2010, 03:24 PM

I was trying to remove a logical volume, but used the lvremove command incorrectly.

I did something stupid like:

Code:

lvremove somelv myvg

Thinking it would remove somelv from myvg

But instead it said "volume group somelv: not found" and then deleted all the logical volumes in myvg. Is there any way to restore them or is it reinstall time?

I had some backups of my system, but unfortunately they were stored on a logical volume in the same volume group. (Yeah, bad idea. I know)

hughetorrance · 06-12-2010, 03:55 PM

Parted Magic has a utility called Test Disc that will find and restore deleted partitions... ! I have use it successfully many times,unfortunately though I had to give up on it as it found loads of rubbish and I did,nt fancy writing all that to the table...

piratesmack · 06-12-2010, 04:23 PM

Thank you, hughetorrance.

It looks like test disk has found my logical volumes, but it is saying the file system looks damaged.

hughetorrance · 06-13-2010, 03:33 AM

Have you tried running e2fsck -p from a terminal on the Parted Magic utility, the -p argument means fix no questions...The UBCD is a great utility with loads of stuff and tools,download the free version.(Google to find it)
Parted Magic has unetbootin a great utility for adding a few of your favourite utilities onto a USB thumb drive... you could have Parted Magic,UBCD and Slax all on one drive... if you can identify what part of the file system is borked it may be possible to replace the whole file/folder from one on another Slack based distro...

it dos,nt always work but its amazing what you can get away with... sometimes LOL

GazL · 06-13-2010, 05:17 AM

The syntax of the lvremove command is downright dangerous in accepting a vgname as an argument in the way that it does - definitely one to watch out for.

Every time lvm makes a change to it's layout, it takes a backup and puts it in a file in /etc/lvm/backup. Old ones get moved to /etc/lvm/archive. You can restore lvm to a former state/point-in-time with these using the vgcfgrestore command.

These backups/archives are just text files that describe the lvm layout. You can grep (or even diff) them to find out which one you need to restore from. Here's mine as an example:

Code:

root@nix:/etc/lvm/archive# grep description /etc/lvm/archive/rootvg* /etc/lvm/backup/rootvg
/etc/lvm/archive/rootvg_00000.vg:description = "Created *before* executing '/sbin/vgscan --mknodes --ignorelockingfailure'"
/etc/lvm/archive/rootvg_00001.vg:description = "Created *before* executing 'lvextend -L 8G /dev/rootvg/lvhome'"
/etc/lvm/archive/rootvg_00002.vg:description = "Created *before* executing 'lvcreate -L 80G -n lvlocal rootvg'"
/etc/lvm/backup/rootvg:description = "Created *after* executing 'lvcreate -L 80G -n lvlocal rootvg'"
root@nix:/etc/lvm/archive#

(edit: you can also do a 'vgcfgrestore -l vgname' to list the above)

'vgcfgrestore' only restores the lvm structure, and doesn't touch the filesystems themselves or their data. It relies on that filesystem structure/data still being intact and unchanged on the same sectors of the disk as it was before. I don't know much about 'testdisk' or whether it's lvm aware, but if it's not and it made any changes to your disks in an attempt to recover things, then it's possibly done more harm than good and restoring from the above might no longer be viable.

If your root fs is on a lvm volume itself, it's a good idea to regularly copy /etc/lvm to somewhere else outside of lvm for safe keeping. I copy mine to my non-lvm /boot filesystem for safe keeping and easy access in the event of a disaster - in addition to including it in my normal backups.

best of luck.

STANDARD DISCLAIMER:
I offer this information as a starting point only. Do your own research on this topic before taking any actions. Don't assume that anything I've said is either correct or appropriate for your situation.

piratesmack · 06-13-2010, 01:27 PM

I ended up reinstalling, but thanks guys.
Good advice, GazL, I'll start backing up /etc/lvm.