[libvirt-users] [libvirt] libvirt external disk-only snapshot will pause the VM?

[Yuanzhen Gu]

On Wed, Aug 6, 2014 at 1:23 PM, Eric Blake <eblake at redhat.com> wrote:

> On 08/06/2014 11:17 AM, Yuanzhen Gu wrote:
>
> >> Guest freeze/thaw (virDomainFSFreeze) only works on a live guest.  So
> >> what you will have to do is:
> >>
> >> virDomainFSFreeze(vm1, ...)
> >> virDomainFSFreeze(vm2, ...)
> >> virDomainSuspend(vm1)
> >> virDomainSuspend(vm2)
> >> virDomainSnapshotCreateXML(vm1, ...)
> >> virDomainSnapshotCreateXML(vm2, ...)
> >> virDomainResume(vm1)
> >> virDomainResume(vm2)
> >> virDomainFSThaw(vm1, ...)
> >> virDOmainFSThaw(vm2, ...)
> >>
> >
> >     I see, thanks.
> >
> >>
> >> However, I honestly don't know why you think you need disk snapshots
> >> from the same point in time across multiple VMs, though.
> >
> >
> >    you suggested that external disk-only snapshot, libvirt will
> freeze/thaw
> > before/after taking snapshot
>
> For a single guest, yes, libvirt can handle both the freeze/thaw and any
> necessary pause/resume of the guest automatically.  But as soon as you
> are coordinating multiple guests, it is up to you do to the
> coordination.  Libvirt handles the case of taking a snapshot when the
> guest is already frozen and paused, but the burden of doing the three
> steps in parallel across VMs is now up to you instead of all three steps
> in a single API call for one VM.
>

    I see, thanks Eric.

>
> --
> Eric Blake   eblake redhat com    +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
>
>
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