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[linux-lvm] disaster recovery



Hello List,

two days ago a harddisk died (IBM imfamous click of death - after 2 years of operation).

The harddisk was disk two (PV) of a two disk VG with several LV's inside.

The system continued to run fine, though I had to unmount some LVs. Some where still mounted from this VG and they continued to work well (those are probably on the remaining good disk)

Now I've ordered and recieved new disks promptly and since they are quite larger than those in use, I could remove all active disks, ie the damaged one AND the good one. I'm running with fresh disks now.

Still I'd like to get the valid data out of the good disk. Since it remained running (/usr is among one of them - and the system continued to execute programs underneath /usr) I am fairly sure that this data should be recoverable.

I had several LVs in the VG, most where quite small, the last one was large and spanned both disks but I'm quite sure it "began" on the good one also. Now I've read a bit in the archive and searched for howto's - but I've still got some questions on how to proceed.

Because I've needed to shut down the machine anyway, I just made a complete software upgrade. Now I'm running a SuSE 8.1 - with all relevant security patches applied.

I'm wondering if I have all the tools required to attemp to recover the remaining data from the good drive?

I keep reading about a "LVM2" - can anyone shortly tell me what exactly that is? Only new userspace utilities? complete new LVM subsystem?

Do I need LVM2 to recover my data or do I already have all I need? (Version of vgdisplay for example is) :
vgdisplay: Logical Volume Manager 1.0.5(mp-v6)
Heinz Mauelshagen, Sistina Software 15/07/2002 (IOP 10)


Do I need to build my own kernel if I need LVM2? I'd like to skip that at the moment. I always build my own kernel, that's not a problem per se, but I am still rebuilding the machine and I'd like to do that only once - at the end when everything is fine again.

Now once I have all the tools necessary, am I right that I basically need to execute vgscan and vgchange and they should be able to activate the VG even when one disk is missing, right? I tried that on the still damaged system and I couldn't get vgchange to activate the VG - it just didn't do it.

Also I ran vgcfgrestore once, but it segfaulted. pvdisplay though reported good looking data from the good drive. That was on the old system though (with old LVM tools, status at about SuSE 7.3 level (although security upgrades where always applied)).

But before I really try to get the data out I just want to be sure I do everything correct.

btw: Do I have a chance of getting part of the data from the LV out, that was spanning the disks? The filesystem was reiser, I think it should be able to handle that (and the beginning of the fs should be on the good disk). Or is that just out of the window anyhow?

Thanks for all answers in advance.

CU

René




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