From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (ext-mx13.extmail.prod.ext.phx2.redhat.com [10.5.110.18]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id p56DRv5G014487 for ; Mon, 6 Jun 2011 09:27:57 -0400 Received: from agslnx2.affinitygs.com (ns6.affinitygs.com [69.84.79.108] (may be forged)) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p56DRtZO014914 for ; Mon, 6 Jun 2011 09:27:55 -0400 Received: from [10.1.10.82] (bisleglnx2.affinitygs.com.10.1.10.in-addr.arpa [10.1.10.2] (may be forged)) by agslnx2.affinitygs.com (8.14.3/8.14.3) with ESMTP id p56Dj0JK020514 for ; Mon, 6 Jun 2011 08:45:00 -0500 Message-ID: <4DECD5C6.9010405@affinitygs.com> Date: Mon, 06 Jun 2011 08:27:34 -0500 From: Anthony Nelson MIME-Version: 1.0 References: In-Reply-To: Content-Type: multipart/alternative; boundary="------------080008040003010703050708" Subject: Re: [linux-lvm] LVM label lost / system does not boot Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: To: LVM general discussion and development This is a multi-part message in MIME format. --------------080008040003010703050708 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Don't think I'm much of an expert in this area, but I had a similar issue that I worked through last week. I wasn't using mdadm, but I don't really think this is a situation that is really relevant to that. I posted the question on serverfault and got enough help to get me through it. You can see it here: http://serverfault.com/questions/275679/rescue-disk-is-unable-to-see-the-lvm-physical-volumes The suggestion that got me on the right track seems to be very similar to your situation. How to recover your lvm configuration with mdadm. http://www.howtoforge.com/recover_data_from_raid_lvm_partitions The steps I went through were basically: * Recover config using dd per steps in that article * Recreate the physical volume using the same device * Do a pvcfgrestore on the recovered config from step 1 That got me back up and running. I hope it helps. Anthony Nelson Affinity Global Solutions 701.223.3565 Ext: 13 On 6/5/2011 7:47 AM, Andreas Schild wrote: > Hi > The first part might sound like I am in the wrong group, but bear with > me... > (I probably am, but I googled up and down RAID and LVM lists and I am > still stuck): > I have a software RAID 5 with 4 disks and LVM on top. I had one volume > group with two logical volumes (for root and data). > I wanted to upgrade capacity and started by failing a drive, replacing > it with a bigger one and let the RAID resync. Worked fine for the > first disk. The second disk apparently worked (resynced, all looked > good), but after a reboot the system hung. > After some back and forth with superblocks (on the devices, never on > the array) I was able to re-assemble the array clean. > The system still does not reboot though: "Volume group "cmain" not found". > > I booted a live cd, assembled the array and did a pvck on the array > (/dev/md0): > "Could not find LVM label on /dev/md0" > pvdisplay /dev/md0 results in: > No physical volume label read from /dev/md0 > Failed to read physical volume "/dev/md0" > > I do not have a backup of my /etc/ and therefore no details regarding > the configuration of the LVM setup (yes, I know...) > All I have of the broken system is the /boot partition with its content > > Several questions arise: > - Is it possible to "reconstitute" the LVM with what I have? > - Is the RAID array really ok, or is it possibly corrupt to begin with > (and the reason no LVM labels are around)? > - Should I try to reconstruct with pvcreate/vgcreate? (I shied away > from any *create commands to not make things worse.) > - If all is lost, what did I do wrong and what would I need to backup > for a next time? > > Any ideas on how I could get the data back would greatly be > appreciated. I am in way over my head, so if somebody knowledgeable > tells me: "you lost, move on" would be bad, but at least would save me > some time... > > Thanks, > Andreas > > > _______________________________________________ > linux-lvm mailing list > linux-lvm@redhat.com > https://www.redhat.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ --------------080008040003010703050708 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: 8bit Don't think I'm much of an expert in this area, but I had a similar issue that I worked through last week. I wasn't using mdadm, but I don't really think this is a situation that is really relevant to that.

I posted the question on serverfault and got enough help to get me through it. You can see it here:
http://serverfault.com/questions/275679/rescue-disk-is-unable-to-see-the-lvm-physical-volumes

The suggestion that got me on the right track seems to be very similar to your situation. How to recover your lvm configuration with mdadm.
http://www.howtoforge.com/recover_data_from_raid_lvm_partitions

The steps I went through were basically:
* Recover config using dd per steps in that article
* Recreate the physical volume using the same device
* Do a pvcfgrestore on the recovered config from step 1

That got me back up and running. I hope it helps.
Anthony Nelson
Affinity Global Solutions
701.223.3565 Ext: 13

On 6/5/2011 7:47 AM, Andreas Schild wrote:
Hi
The first part might sound like I am in the wrong group, but bear with me...
(I probably am, but I googled up and down RAID and LVM lists and I am still  stuck):
I have a software RAID 5 with 4 disks and LVM on top. I had one volume group with two logical volumes (for root and data).
I wanted to upgrade capacity and started by failing a drive, replacing it with a bigger one and let the RAID resync. Worked fine for the first disk. The second disk apparently worked (resynced, all looked good), but after a reboot the system hung.
After some back and forth with superblocks (on the devices, never on the array) I was able to re-assemble the array clean.
The system still does not reboot though: "Volume group "cmain" not found".

I booted a live cd, assembled the array and did a pvck on the array (/dev/md0):
"Could not find LVM label on /dev/md0"
pvdisplay /dev/md0 results in:
  No physical volume label read from /dev/md0
  Failed to read physical volume "/dev/md0"

I do not have a backup of my /etc/ and therefore no details regarding the configuration of the LVM setup (yes, I know...)
All I have of the broken system is the /boot partition with its content

Several questions arise:
- Is it possible to "reconstitute" the LVM with what I have?
- Is the RAID array really ok, or is it possibly corrupt to begin with (and the reason no LVM labels are around)?
- Should I try to reconstruct with pvcreate/vgcreate? (I shied away from any *create commands to not make things worse.)
- If all is lost, what did I do wrong and what would I need to backup for a next time?

Any ideas on how I could get the data back would greatly be appreciated. I am in way over my head, so if somebody knowledgeable tells me: "you lost, move on" would be bad, but at least would save me some time...

Thanks,
Andreas


_______________________________________________
linux-lvm mailing list
linux-lvm@redhat.com
https://www.redhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
--------------080008040003010703050708--