[Cinder][nova] queens backup
ignaziocassano at gmail.com
Wed Jan 23 18:34:13 UTC 2019
Thanks for the info.
Il giorno Mer 23 Gen 2019 19:29 melanie witt <melwittt at gmail.com> ha
> On Wed, 23 Jan 2019 18:02:56 +0100, Ignazio Cassano
> <ignaziocassano at gmail.com> wrote:
> > Manu thanks.
> > I read a blueprint for providing quiesce function to nova api but I
> > cannot find it.
> > Must I talk directly with libvirt api?
> Quiesce was never added to the nova API as a separate function and a
> spec proposal to add it was last reviewed in Newton . At the time of
> review, only one virt driver, libvirt, supported quiesce and the
> justification to add a new REST API that all but one driver could not
> support, was not compelling enough. AFAIK the libvirt driver is still
> the only one that supports quiesce. There were other concerns beyond
> that though, and they are detailed in the review.
> As Matt Riedemann mentioned in his earlier reply on this thread , a
> quiesce step is integrated into the nova snapshot API, if the driver
> supports it (only libvirt). This is the only way you can quiesce an
> instance today.
>  https://review.openstack.org/295595
> > Il giorno Mer 23 Gen 2019 17:01 Sean McGinnis <sean.mcginnis at gmx.com
> > <mailto:sean.mcginnis at gmx.com>> ha scritto:
> > On Wed, Jan 23, 2019 at 04:56:24PM +0100, Ignazio Cassano wrote:
> > > Hello, I did not understand if you mean cinder snapshot pr netapp
> > snapshot.
> > > Any case, why, we do not need to quiesce the instance ?
> > > Regards
> > > Ignazio
> > >
> > If being crash consistent is good enough for your needs, then you
> > don't. I know
> > some do prefer the coordinated quiescing of IO in the instance to
> > make sure any
> > in-flight transactions are flushed out and application data is more
> > likely to
> > be in a good consistent state.
> > Depending on your application running in the instance, things like
> > databases
> > are pretty good at rolling back incomplete transactions, so it's
> > just a matter
> > of whether you can allow the possibility that something that was
> > successful in
> > the milliseconds before the snap was created to now be rolled back
> > when the
> > application restarts.
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