Re: Preserving LVM across builds
On Sat, Jan 18, 2014 at 3:26 AM, Brad Alexander <storm16@gmail.com> wrote:
> Hey,
>
> Have a question that I thought I would post here because I have never done
> it before.
>
> I have a buddy that has a system that is in desperate need of a rebuild. It
> is truly a Franken-box, with 4 hard drives (2*80GB, 1*160GB, and 1*250GB),
Sounds like the box I'm working on, except I only have one 80G drive,
and I have a 350G drive instead of a 250G drive.
> and has an Ubuntu build on it and a Mint build. He wants to consolidate it
> into a single Debian build.
Yeah, various versions of various systems, here, too.
I have migrated my data between the drives over some 12-odd years in a
haphazard pattern, losing the lvm partitions and finding them a couple
of times in the process.
> The 250GB drive is an LVM PV with a single VG and two LVs. Unfortunately, he
> doesn't have sufficient drive space to move the data from the drive.
LVM is pretty good about being able to re-construct botched volumes
and volume groups in many cases, but studying the commands to do so
with your conscience telling you that you should have made a backup is
no fun. I speak from experience.
(And, yes, I need to fix my backup policy again. The big drive was
intended as a backup, but it is now a bit more than that, which puts
some of my data at risk.)
> My
> question is what needs to be done (or if it is possible) for him to unplug
> that drive with the LVM, install Debian on one or more of the remaining
> drives, then re-incorporate the drive into the new Debian install? Is it
> possible? And what is the best approach to doing so?
As everyone says, he'll have more freedom to move if he spends the
money for a half-T or bigger, and backs his data up.
> Thanks,
> --b
One physical volume and one volume group with two logical volumes
should be straightforward for the LVM.
If all of his data is on that LVM, what he wants to do is pretty
straightforward, other than needing to keep track of which packages he
wants to keep in the new OS. If not, he needs to plan the move a bit
more carefully.
Figuring out what needs to be backed up from where is probably the
first thing he needs to do.
If he still has the /usr, /bin, /var, etc. from the Ubuntu and Mint
installs, those can be reclaimed and used for intermediate storage.
It's tempting to talk about the possible problems now, but I think I
want to ask what he's worried about.
Is the problem a lack of experience with moving data, or are there
specific issues with joined partitions, database storage spanning
various branches of the file system tree, encrypted parts of the tree,
etc.? It doesn't sound like he's using RAID ...
Does he know what is on all those drives? Does he know where all his
data is? How is the data spread across those drives?
Is he able to get a list of all the application packages he wants to
be able to use? Does he know which applications he just can't live
without, so he can check that they are available and work on Debian?
Questions like that should help him plan his strategy.
--
Joel Rees
Be careful where you see conspiracy.
Look first in your own heart.
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