Re: [gentoo-user] How to change from one harddrive to software raid

[Mark Shields <laebshade@gmail.com>]

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On Wed, Mar 30, 2011 at 8:21 PM, Einux <einuxnet@gmail.com> wrote:

> thank you guys, you've been helpful :)
>
> On Wed, Mar 30, 2011 at 3:31 PM, Joost Roeleveld <joost@antarean.org>wrote:
>
>> On Wednesday 30 March 2011 07:28:40 Florian Philipp wrote:
>> > Am 30.03.2011 05:02, schrieb Einux:
>> > > Hi,
>> > >
>> > > I bought a new 1T harddrive which is exactly the same as my previous
>> > > harddrive. So I'm planning to make a Raid-1 layout(for security
>> > > reasons). But here's the problem: I've already setup LVM2 on the
>> > > existing harddrive and I don't want to destroy the existing LVM volume
>> > > groups. I tried to google it, but I'm not sure which is the right
>> > > keyword. Could you guys help me out?
>> > >
>> > > Thanks in advance:)
>> >
>> > 1. Create a degenerated RAID1 with your new disk
>> > mdadm --create /dev/md0 --level=1 --raid-devices=2 missing /dev/sdb
>> >
>> > 2. Partition the raid device
>> >
>> > 3. Add one of the partitions to your LVM volume group.
>> > pvcreate /dev/sdb2
>> > vgextend volume_group /dev/sdb2
>> >
>> > 4. Move everything from the old physical volumes to the new pv.
>> > pvmove /dev/sda3 /dev/sdb2
>> >
>> > 5. Remove the old and now empty physical volume
>> > vgreduce volume_group /dev/sda3
>> >
>> > 6. Move everything else which is not on LVM to your new raid. Guess you
>> > need to go to single user mode to do this safely.
>> >
>> > 7. Grow your raid to also contain the old disk.
>> > mdadm /dev/md0 -a /dev/sda
>> >
>> > No, I have not tested this and you should double-check everything. No
>> > guarantees, etc.
>> >
>> > One warning, though: pvmove is known to create problems from time to
>> > time. Leaking memory, bogging systems with infinite system load and so
>> > on. If it gives you trouble, you can abort it with `pvmove --abort` and
>> > try it again later by calling `pvmove volume_group` (without physical
>> > device specified) to resume it. It SHOULD survive system crashes.
>> > Trying another kernel version sometimes helps when pvmove gives you
>> trouble.
>>
>> To avoid that, with "large" moves, do the following:
>> # pvmove -i 600 /dev/sda3
>>
>> The "-i 600" means, only report every 10 minutes. It's the "reporting"
>> that
>> causes the memory leak.
>>
>> Also, when just wanting to "empty" one physical volume, it is not
>> necessary to
>> specify the "target".
>> It's a good idea to mark the PVs on the existing drive "non-allocatable".
>> Then
>> LVM won't try to move anything to that PV:
>> # pvchange -xn /dev/sda3
>>
>> The rest of the steps read correct. It's how I did a similar operation,
>> but
>> still double-check all the parameters and when in doubt, read the manual
>> and/or ask on the list.
>>
>> --
>> Joost Roeleveld
>>
>>
>>
>
>
> --
> Best Regards,
> Einux
>
> I starred this in Gmail in case I ever need to do something like this.
 Thanks guys!

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