Re: [linux-lvm] pvmove: moving a mirror logical volume not supported?

[Morten Torstensen <morten@mortent.org>]

Alasdair G Kergon wrote:
> On Wed, Sep 06, 2006 at 11:14:13AM +0200, Jens Wilke wrote:
>> What is the reason for this?
> 
> No code to do this has yet been written.
> There should be no fundamental problems with doing it.

pvmove is a wrong approach to the problem too, imo. PVs are just storage devices 
for a VG. By moving LVs (or the PEs that the LV resides on), you accomplish the 
same. When there are no PE in use on a PV, it is easy enough to reduce the VG to 
remove the PV.

Like in this scenario when you want to move a VG from an internal disk to, let's 
say SAN volume (with pseudo-commands):

Assuming VG is pn /dev/scsi and new disk is /dev/sandisk.

# extendvg myvg /dev/sandisk
# lvmirror myvg copies=1 strict=1

(one mirror, allocate strict so copies are on different PVs)

Now check that LVs are in sync and that all is OK with the new disk...

# lvmirror myvg copies=0 remove=/dev/scsi
# reducevg myvg /dev/scsi

This strategy would assume that mirroring is done in PE/LE mapping levels.

I have no idea if Linux LVM mirroring supports this. If anyone have links to 
good LVM docs for the mirroring features that will come with LVM in RHEL5 I 
would appreciate it.


-- 

//Morten Torstensen
//Email: morten@mortent.org
//IM: Cartoon@jabber.no morten.torstensen@gmail.com

And if it turns out that there is a God, I don't believe that he is evil.
The worst that can be said is that he's an underachiever.