howto import existing linux soft array volume group

Question

I have a server that consists of a boot drive, then two data drives combined to a RAID1 linux array. My boot drive recently became corrupted and I need to re-install the operating system. The RAID1 data array is fine, and I would like to just import it once the operating system is installed. (The data array is just a big LVM setup in a volume group)

What steps should I go through to import the volume group, and LVM within the array? Google has been surprisingly unhelpful for this.

Thanks in advance

Answer 1

Maybe you can try to follow the recipe for moving volumes in the LVM Howto? Of course you'll skip a few steps there.

Answer 2

What distribution is this?

You will need to enable lvm and dm at boot - as said, lots of dists will do this automatically, but Opensuse does not for example. How you ensure these are enabled at boot are distro dependent.

You say that the raid1 is fine, so you'll need to assemble it:

mdadm --assemble --scan --auto=yes /dev/md0 

Once you have the array up and running, recreate your mdadm.conf:

/sbin/mdadm --examine --scan >> /etc/mdadm/mdadm.conf 

Then restart lvm - this is a bit distro dependent too - but

/etc/init.d/lvm2 restart 

is the debian way

This should scan your volume groups and find the logical volumes.

Note that vgscan should be enough to find them and find the lvs, and then

lvdisplay -C 

Gives you a compact list of volumes.

Answer 3

Practically all modern Linux installers will detect presence of your data drives RAID and an LVM group on them. You'll need just to choose mount points for logical volumes and remember not to format them, which, at least for Fedora, is the default.

If you decide to disconnect your data drives during installation and reconnect on OS boot, your RAID and LVM should be auto-detected too. You'll need to look up devices created in /dev/ and edit your fstab accordingly.