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

[Einux <einuxnet@gmail.com>]

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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

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