[openstack-dev] live-snapshot/cloning of virtual machines

Russell Bryant rbryant at redhat.com
Tue Aug 27 13:48:51 UTC 2013

On 08/26/2013 08:15 PM, Tim Smith wrote:
> Hi all,
> On Mon, Aug 19, 2013 at 11:49 PM, Bob Ball <bob.ball at citrix.com
> <mailto:bob.ball at citrix.com>> wrote:
>     I agree with the below from a XenServer perspective.  As with
>     vmware, XenServer supports live snapshotting and creating multiple
>     clones from that live snapshot.
>     I understand that there is a XenAPI equivalent in the works and
>     therefore would argue the API changes need to be accepted as a minimum.
> Can nova technical leadership provide clarification on the current
> standing of this blueprint? Two hypervisor vendors have expressed plans
> for supporting this feature, and one has specifically requested that the
> API changes be merged, but it appears that both the API changeset [1]
> and novaclient support [2] have both been rejected pending libvirt
> support (which has assumedly been ruled out for the Havana release).
> [1] https://review.openstack.org/#/c/34036/
> [2] https://review.openstack.org/#/c/43777/ 
>     In order to minimize the feature divergence between hypervisors, I'd
>     also argue that we should accept the libvirt implementation even if
>     it uses unsupported APIs - perhaps disabled by default with a
>     suitable warning that it isn't considered safe by libvirt/QEmu.
> It's understandable that changes to the libvirt driver would be held
> back until libvirt/qemu-upstream support for live snapshotting is
> established (if ever), but given that other vendors whose release
> cadences don't necessarily align with the nova release schedule have
> expressed plans to support the interface it's unclear why lack of
> libvirt driver support would block the entire blueprint.

Two other driver maintainers have expressed interest in it, but AFAIK,
there are not implementations of this feature ready for review and
merging for these drivers.  Given that's the case, it doesn't make any
sense to me to merge the API with no ability to use it.  I'm only saying
it should wait until it can be merged with something that makes it usable.

Russell Bryant

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