A couple of things i have set up for. The initital install is on LVM
already so most of that was in place (including /) and i have no data on
this. so if it wrecked its only an install away to start over.
But this is a good start for some reading, thank you!
On Thu, Jul 23, 2015 at 9:12 AM, Matt Graham <
mhgraham@crow202.org> wrote:
> On 2015-07-21 13:28, Stephen Partington wrote:
>
>> Ubuntu 15.04 installed and am looking to find out if there is a way
>> to migrate to raid on a running system.
>>
>> In theory i should be able to do this by creating a degraded portion
>> of the raid volume on the empty disk, extend/move my LVM to that disk
>> then rebuild the original disk as part of that raid volume.
>>
>
> This is a softRAID-1, right? That makes the most sense for what you've
> said.
>
> I was wondering if anyone had some documentation of information i
>> could read about this scenario.
>>
>
> I did something like this when I moved my stuff from just 1 disk on
> regular partitions to softRAID-1. First, back up all your junk, because
> there are multiple points in this where you could scribble all over your
> disks. Second, make sure you have a LiveCD or LiveUSB disk to boot from if
> the bootloader goes wonky.
> https://wiki.gentoo.org/wiki/Complete_Handbook/Software_RAID should be
> pretty applicable to working with softRAID and applicable to distros that
> are not Gentoo.
>
> You'd first take the new disk and partition it. I would think you'd need
> at least 2 partitions since having /boot on LVM is not going to work, and
> possibly 3 because having / on LVM has more fiddly bits than having it on a
> regular partition.
>
> So, fdisk /dev/sdb , set it up with 2 or 3 partitions (whichever), and
> then set up the RAID. This'll assume that your largest partition (the one
> that'll be your PV) is /dev/sdb2 . You'd then do
>
> mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb2 missing
>
> This'll set up an array in degraded mode on /dev/md0. You'd then pvcreate
> /dev/md0 , then vgextend $VG_NAME /dev/md0 , then pvmove
> /dev/$OLD_PV_LOCATION . Then vgreduce $VG_NAME /dev/$OLD_PV_LOCATION and
> pvremove /dev/$OLD_PV_LOCATION to remove the old PV from lvm's config.
> Then you'd add the old PV back to the md0 with mdadm /dev/md0 --add
> /dev/$OLD_PV_LOCATION . The disk sync will probably take a while.
>
> You'll have to set things up so that the bootloader can figure everything
> out. Are you going to put / on LVM? That requires that the initrd have
> all the LVM tools on it. I don't know if Ubuntu can handle that
> automatically or not--I would guess so, but ICBW.
>
> --
> Crow202 Blog: http://crow202.org/wordpress
> There is no Darkness in Eternity
> But only Light too dim for us to see.
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--
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Stephen
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