[gentoo-user] LVM Recovery....

[BRM <bm_witness@yahoo.com>]

Okay, so I have a desktop running Gentoo 2008.0 (pre-2008.0 release) that has been a little problematic for a while. The power supply died last May/early June - or rather the system wouldn't boot with that power supply - and it hasn't really been booted since early june at the latest. I just got a new power supply for it, got everything connected and it started up without any issues.

So I decided to sync portage and update (emerge --sync && emerge world -vuDN). After a little bit of playing around with package masks (since I had a few packages unmasked and it was being a problem) I got it straightened away, and let is sit for the night last night to continue on its merry way of updating.

Well..I checked up on it a little while ago, and there was a kernel panic in the middle of a build - reporting a hardware error and recommending looking at mcelog --ascii. Okay. So I restart the system and hear a bit of clicking - and the system won't go past POST. Argh.

Well, I turns out my SATA drive was making the clicking sounds; so I disconnected the power and it booted, only it can't find all the Volumes for the Volume Group configuration since one of the three hard drives is disconnected. This is a first for me - I only started using LVM this last spring, and only on this system.

So now I need to get the system backup and running, and start assessing if I need to do any data recovery. I think the two kind of go hand-in-hand at this step since I need to know the mapping to get the system up and running, and I will also need to know that to assess the situation for data recovery...

I looked at the files in /etc/lvm/backup and /etc/lvm/archive to get an idea of what volumes in the group were on that drive.
Question #1: Is there any where else I should look as well?

From the files there I can see I only had data 4 volumes on the drive in question - and they were all only assigned to two single logical partitions - /opt and /usr/local.  I have only installed stuff via emerge; and a search through the root partition using "ls -lR | grep ^l" revealed only symlinks for a few things - netscape plugins, blackdown jdk, sun jdk, eselect linux java, and skye - being on /opt. So...

Question #2: How do I easily recover the installation so that when I replace /opt and /usr/local with a new mapping they will be replenished with whatever was installed?

(I am assuming any important settings were stored to either /etc or the user's home directory. So I am not worried about recovery on at least /opt; and I doubt I should be worried about /usr/local too.)


Question #3: What do I need to do to get the LVM backup so I run the system again?
I found an article on line [1] but am not sure if that is the wisest manner - partly due to that I have physical volume<->logical volumes spreading disks. I am also not 100% sure if the backup is accurate.

Question #4: Is there a way to get the mapping that LVM is searching for? I try running "lvm vgcfgbackup", however, it fails b/c it can't find all the physical volumes in the volume group.

Note: I think the only thing I changed in /etc/lvm.conf was the filter so it would find the hard drives appropriately. Otherwise, I believe it is the base on from the initial emerge of LVM2; however, it's been quite a while since I last touched anything with LVM.

This is a first for me. Right now, I'm more concerned with getting the system back up and running - I can worry about data recovery later.

TIA,

Ben


[1]http://www.linuxjournal.com/article/8874