[Gllug] still wondering about lvm

[Nix]

On Tue, 14 Mar 2006, Bruce Richardson uttered the following:
> On Tue, Mar 14, 2006 at 08:06:13AM +0000, Ken wrote:
>> Another LVM question..... I was experimenting with LVM on an old machine 
>> with 3 disks. The LV was spread over those platters. It's (was) working 
>> great. It seems that this is the month for disk failures as one of the 3 
>> is now giving bad block errors. Anyway here is my question.... If I move 
>> the three disks to another machine to extract a few bits of data I'd 
>> like to keep does LVM worry that hda has become hdb, hdb has become hdc 
>> and hdc has become hdd or is the header (metadata) in the PV's enough 
>> for LVM to find what it needs and sort itself out?
> 
> LVM cares about the UUIDs of the PVs, nothing else.  Two things to note:
> 
> 1. Export the volume group (vgexport) on the original machine before you
> move them, then vgimport them on the other.
> 
> 2. If you have a volume group of the same name on the other machine,
> this will cause you problems when you add in the extra disks.  In that
> scenario, rename the volume group on the disks that will be moved
> *before* you move them.

A third note is that if PV that is part of a VG dies, you lose the entire
VG until you do a vgreduce --removemissing (and that command is somewhat
risky).

Myself I've got a separate VG covering my robust devices (i.e., RAID)
and one covering the un-RAIDed stuff I don't much care about (if it dies,
I lose a bunch of MP3s and have to re-encode them, and a bunch of news
I have to refetch. Big deal.)

-- 
`Come now, you should know that whenever you plan the duration of your
 unplanned downtime, you should add in padding for random management
 freakouts.'
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