[libvirt-users] Migrate VM's to different storage pool?

Kashyap Chamarthy kchamart at redhat.com
Fri Feb 22 10:00:31 UTC 2013


On 02/13/2013 12:31 AM, Jamie Fargen wrote:
> Eric,
> 
> Following along with your direction I get stuck at virsh blockcopy. I receive an error
> "unsupported configuration: block copy is not supported with this QEMU binary."
> 
> As I originally explained this host is running Red Hat EL6.3.
> 
> Is live blockcopy supported in EL6.3?


This after discussion from Eric.

A small example. Note this was on latest Fedora, though:

http://kashyapc.fedorapeople.org/virt/lc-2012/live-backup-with-blockcopy.txt


> 
> Packages:
> qemu-kvm-0.12.1.2-2.295.el6_3.2.x86_64
> libvirt-client-0.9.10-21.el6_3.4.x86_64
> 
> Regards,
> Jamie Ian Fargen
> 
> 
> On Tue, Feb 12, 2013 at 10:12 AM, Eric Blake <eblake at redhat.com
> <mailto:eblake at redhat.com>> wrote:
> 
>     On 02/12/2013 06:22 AM, Jamie Fargen wrote:
>     > Eric-
> 
>     [Please don't top-post on technical lists]
> 
>     >
>     > Why wouldn't a 'virsh blockcopy --pivot domain src dest' be sufficient to
>     > migrate the volumes to a new storage pool?
> 
>     It IS sufficient, as part of the sequence I documented here:
> 
>     >>
>     >> # save off the persistent definition for later
>     >> virsh dumpxml --inactive $dom > $dom.xml
>     >> # make the guest transient
>     >> virsh undefine $dom
>     >> # remind myself which disks need migration
>     >> virsh domblklist $dom
>     >> # for each disk (such as "vda"), do a migration
>     >> virsh blockcopy $dom $disk /path/to/new --wait --verbose --pivot
>     >> # make the guest persistent again
>     >> virsh define $dom.xml
> 
>     Or maybe I'm misunderstanding your question.  Are you asking why
>     blockcopy doesn't work with a persistent domain?  And the answer to that
>     is because as of at least qemu 1.4, there is no support for remembering
>     the progress of a block copy across a domain restart; there have been
>     patches proposed for qemu 1.5 that add a persistent bitmap, and there
>     are plans to teach libvirt to use this new feature to allow 'virsh
>     blockcopy' even for a persistent domain, so that you don't have to
>     juggle through the steps of going to a transient domain just to do the
>     blockcopy.
> 
>     --
>     Eric Blake   eblake redhat com    +1-919-301-3266 <tel:%2B1-919-301-3266>
>     Libvirt virtualization library http://libvirt.org
> 
> 
> 
> 
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> 


-- 
/kashyap




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