[libvirt] [PATCH] save state as string

Guido Günther agx at sigxcpu.org
Wed Jan 7 09:38:03 UTC 2009


On Tue, Jan 06, 2009 at 05:51:27PM +0000, Daniel P. Berrange wrote:
[..snip..] 
> > The file we write is /var/run/libvirt/qemu/*.xml where we keep the
> > internal state of a running vm. We can change this at at any time.
> 
> Yes & no, but mostly no.
> 
> These persistent state files will need to be stable across releases of
> libvirt, to allow sensible live upgrade path for hosts. eg, you're
> running libvirtd with several VMs, upgrade to latest RPM which does
> a 'service libvirtd restart' in the %post install section. The new 
> libvirtd needs to cope with the state file created by the old libvirtd.
Maybe I was a bit unclear, what I meant to say is: This is internal to
libvirt so if we change the XML format it's only *us* who need to worry
about what changed. E.g. in this case (if there'd been any releases with
this code) we'd have to keep number and string parsing for 
state=....

> In this particular case though, its not problem changing state=1 to
> state=running, since we've not released this code yet and the named
> attribute is nicer to read.
So o.k. to apply this change?
 -- Guido




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