[libvirt] Migrate not running guests

[Hugh O. Brock]

On Mon, Jul 05, 2010 at 08:37:33PM +0200, Juan Quintela wrote:
> 
> Hi
> 
> In an exercise to use more libvirt, I am trying to use libvirt with my
> normal use.  First, I will explain how I normally run my guests.
> 
> I install guests on a machine with virt-install <....>
> I store all my guests images in a shared directory that is mounted in
> all my hosts.
> 
> Now, it is trivial for me to launch qemu-kvm <options> on any machine,
> it don't matters if I have to use a rhel5, rhel6, fedora13 host.
> Everything works as expected.
> 
> Except for the little fact that I have to remember the whole command
> line when I go from one machine to other, to use ide/virtio/rtl8139/....
> You get the idea.  And thing got worse the more guests that I have.
> 
> Now I can run virt-manager on my desktop (machine A).
> Connect to host B.  And launch my guests VM1 (on host B).  No problem so far.
> I can indeed migrate my guests to machine C.  No problem so far.
> 
> And now I can start my guest VM1 in both host B and host C.  It is there
> on virt-manager, one click away of launching.
> 
> The functionality that I would really like is a "way" to store my guest
> information on my desktop (machine A), and be able to launch the guest
> on any host.  I.e. a menu option when I click on the guest, that let me
> launch it in a different host, not in the one that it is defined.
> 
> If that is difficult to implement for now, a "migrate" for a shut off
> guest will do by now.  It should be something like 
>       virsh dumpxml foo > foo.xml
>       virsh define foo.xml
> 
> (this is the way that I do it by hand now).
> 
> Why do I need this?  because I have hosts with RHEL5/RHEL6/F13/....
> 
> And just now, I have to reinstall, do the previous dumpxml/define each
> time that I have to reproduce one bug in one host or another.  To make
> things worse, sometimes RHEL5.4 and RHEL6.0 xml's are not completely
> compatible and I have to fix it by hand.
> 
> Any better ideas about how to do this?

I think this is a great idea... we would simply need to give
virt-manager the ability to start transient guests off a local libvirt
XML definition. I don't even think this would require that much code,
especially if we didn't get worked up about making it super-robust
(i.e. if the nfs path in your guest definition is wrong for the host
you've tried to run your guest on, tough luck).

Cole? Dan?

Take care,
--Hugh
> 
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