[TriLUG] how to restore lvm data
maxlists at maxwellspangler.com
Wed Apr 14 02:48:55 EDT 2010
On Tue, 2010-04-13 at 20:43 -0400, Ralph Blach wrote:
> Ok, I made a bad mistake. I accidentally deleted the partion table for
> a disk but the linux box still has the lvm data on it.
> However system config lvm does not show a /dev/sdc where the lvm's are
> is there a way to recover /dev/sdc to show so that the lvm's are shown
> on /dev/sdc
I'm working with LVM study over here and used my test disk to duplicate
and resolve your problem.
In my case I had a single 300GB maxtor drive with four partitions, two
of which (#1 and #3) were in use as part of a single volume group called
I deleted each of those partitions to duplicate your situation.
Running # vgscan produced errors related to being unable to read disk
blocks from a device-mapper device dm-1.
I rebooted to further simulate the environment you described.
Then I downloaded testdisk (http://www.cgsecurity.org/wiki/TestDisk) and
Testdisk let me select the physical drive being used for testing and
scan it from start to finish to find missing partitions. It easily
found partitions 1 and 3 and let me write a new partition table
identical to the setup before this experiment.
I then ran # partprobe to let the kernel rescan for hard drive
partitions and in this case, it succeed. Sometimes you just have to
reboot (and testdisk suggests this.)
Running # vgscan again with the partitions recovered found the vg_maxtor
Next I re-activated the volume group with the vgchange command:
# vgchange -a y
Then I was able to mount the two logical volumes containing ext4
filesystems that were contained within this volume group.
Please let us know if this process works for you. I hadn't known how to
do this before and just learned it on the fly as part of studying LVM2,
so I enjoyed the opportunity.
Linux, Unix and Database Administration
Currently: Boulder, Colorado
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