[Cinder][nova] queens backup

Matthew Booth mbooth at redhat.com
Wed Jan 23 14:18:51 UTC 2019

On Tue, 22 Jan 2019 at 18:51, Sean McGinnis <sean.mcginnis at gmx.com> wrote:
> On Tue, Jan 22, 2019 at 07:04:05PM +0100, Ignazio Cassano wrote:
> > Hi All,
> > Please,  I' d like to know if cinder backup  and/or  cinder snapshot call
> > qemu guest agent for fsfreezing.
> > If Yes, does it freeze file systems in the volume?
> > Regards
> > Ignazio
> Unfortunately no, initiating a snapshot or backup from Cinder does not call out
> to Nova to do any guest quiescing. There would need to be something else
> coordinating the calls between the guest OS and initiating the Cinder snapshot
> to do that.

Although it wouldn't help making a consistent snapshot of an instance
with multiple disks, for a single disk it shouldn't matter if the
guest is quiesced as long as the backend can make an instantaneous
snapshot. I'm pretty sure many (most?) backends would support that;
certainly plain old LVM does. Does cinder use this functionality where
it's available, and would that solve the problem you're trying to


> Sean

Matthew Booth
Red Hat OpenStack Engineer, Compute DFG

Phone: +442070094448 (UK)

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