[openstack-dev] [nova] Server Groups - remove VM from group?

Russell Bryant rbryant at redhat.com
Mon Aug 25 17:10:59 UTC 2014

On 08/25/2014 12:56 PM, Joe Cropper wrote:
> That was indeed a rather long (and insightful) thread on the topic.
> It sounds like there are still some healthy discussions worth having
> on the subject -- either exploring your [potentially superseding]
> proposal, or minimally rounding out the existing server group API to
> support "add existing VM" [1] and "remove VM" -- I think these would
> make it a lot more usable (I'm thinking of the poor cloud
> administrator that makes a mistake when they boot an instance and
> either forgets to put it in a group or puts it in the wrong group --
> it's square 1 for them)?
> Is this queued up as a discussion point for Paris?  If so, count me in!

Adding a VM is far from trivial and is why we ripped it out before
merging.  That implies a potential reshuffling of a bunch of existing
VMs.  Consider an affinity group of instances A and B and then you add
running instance C to that group.  What do you expect to happen?  Live
migrate C to the host running A and B?  What if there isn't room?
Reschedule all 3 to find a host and live migrate all of them?  This kind
of orchestration is a good bit outside of the scope of what's done
inside of Nova today.

Russell Bryant

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