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

[Daniel Veillard]

[ Please subscribe, manually approving messages gets boring and unreliable
  rather quickly, Daniel ]

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

-- 
Red Hat Virtualization group http://redhat.com/virtualization/
Daniel Veillard      | virtualization library  http://libvirt.org/
veillard at redhat.com  | libxml GNOME XML XSLT toolkit  http://xmlsoft.org/
http://veillard.com/ | Rpmfind RPM search engine  http://rpmfind.net/