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Re: Instance IDs and Multiple Zones

To: Paul Voccio <paul.voccio@xxxxxxxxxxxxx>, Justin Santa Barbara <justin@xxxxxxxxxxxx>, Eric Day <eday@xxxxxxxxxxxx>
From: Ewan Mellor <Ewan.Mellor@xxxxxxxxxxxxx>
Date: Thu, 24 Mar 2011 15:24:19 +0000
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Cc: "openstack@xxxxxxxxxxxxxxxxxxx" <openstack@xxxxxxxxxxxxxxxxxxx>
In-reply-to: <13010_1300922435_p2NNKT8j009492_C9AFE464.155FE%paul.voccio@rackspace.com>
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Thread-topic: [Openstack] Instance IDs and Multiple Zones

> If we were to go with UUIDs and using XenServer, I should be able to use
> the uuid that it generates upon VM creation. I would almost ask your above
> question for XenServer then. When I terminate and launch an VM on the same
> machine, I should be able to give it the same uuid that I was just using,
> but I can't. Maybe I can and I'm making it harder on myself :)

Yes, it would be great if you could use the XenServer-generated UUID.  The reason this doesn't work is because OpenStack is outside of the XenServer design envelope, and is orchestrating on top of it.  If you were using XenServer pools, and only starting, stopping, and migrating VMs within the pool, then you could use our UUID, because the VM retains its identity for the lifetime of all those operations.   It's the fact that OpenStack moves beyond that model that breaks this.  For OpenStack, it might be a VM move, but for XenServer it's a VM copy + VM destroy + VM start for a completely different VM; we lose track of the identity at that point.

Ewan.

References

Re: Instance IDs and Multiple Zones
From: Ewan Mellor, 2011-03-23
Re: Instance IDs and Multiple Zones
From: Paul Voccio, 2011-03-23