[Libvir] persistent guests (save guest at shutdown and reload it at boot)

[Matthias Pfafferodt]

Am Montag, 17. März 2008 15:37:00 schrieb Daniel Veillard:
> [ Please subscribe, manually approving messages gets boring and unreliable
>   rather quickly, Daniel ]

OK, now I'm on the list ...

>
> On Mon, Mar 17, 2008 at 03:20:26PM +0100, Matthias Pfafferodt wrote:
> > Hello,
> >
> > I added the following entry to the libvirt bugzilla (Bugzilla Bug
> > 437204). Daniel Veillard ask me to post this to the list for discussion.
> >
> > Description of problem:
> >
> > libvirt can save and restore guests. It is also possible to autostart
> > guest at boot time. I miss a similar option: 'persistent'
> >
> > booting the host:
> > * the guest is restored if there is a saved version
> > * else it is booted
> >
> > shutdown of the host
> > * the guest is saved
> >
> > The xendomain script does something like this. There the 'autostart'
> > option checks if the domain was saved. If it was this domain is restored
> > else it is created. At shutdown of the dom0 all running domU's are saved.
>
>   That would assume libvirt is always in control of the guest, and that's
> not the case, I assume you would be fine by a 'best-effort' kind of
> support. This might be doable in libvirtd, assuming it intercepts shudown
> properly, and actually has the time to do this. But the elapsed time for
> a an xmlDomainSave option can be fairly long (nearly linear with the
> size of the memory allocated for the domain), this may slowdown
> significantly the shutdown process.
>   What kind of benefits are you trying to get with this ?
>
> Daniel

At the moment I have a server using xen (version 3.0) and the xendomain boot 
script. The server is powered off from time to time. Do to the script the 
guests are saved and restored with all the processes still running. Now I 
plan to update the server and I think about using libvir and kvm.

Is it possible to update the 'autostart' option to check if the guest was 
saved and restore it before creating a new version?

Matthias