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On 06/28/2017 03:34 AM, Sahid Orentino Ferdjaoui wrote:
> On Tue, Jun 27, 2017 at 04:00:35PM +0200, Henning Schild wrote:

>> As far as i remember it was not straight forward to get two novas onto
>> one host in the older release, i am not surprised that causing trouble
>> with the update to mitaka. If we agree on 2 novas and aggregates as the
>> recommended way we should make sure the 2 novas is a supported feature,
>> covered in test-cases and documented.
>> Dedicating a whole machine to either RT or nonRT would imho be no
>> viable option.
>>
>>> The realtime nodes should be isolated by aggregates as you seem to do.
>>
>> Yes, with two novas on one machine. They share one libvirt using
>> different instrance-prefixes and have some other config options set, so
>> they do not collide on resources.
>
> It's clearly not what I was suggesting, you should have 2 groups of
> compute hosts. One aggregate with hosts for the non-RT VMs and an
> other one for hosts with RT VMs.

Not all clouds are large enough to have an entire physical machine dedicated to 
RT VMs.  So Henning divided up the resources of the physical machine between two 
nova-compute instances and put them in separate aggregates.

It would be easier for operators if one single nova instance could manage both 
RT and non-RT instances on the same host (presumably running an RT OS).

Chris