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On Fri, 2014-03-28 at 13:56 +0100, Belmiro Moreira wrote:
> +1 for Phil comments.
> I agree that VMs should spread between different default avzs if user
> doesn't define one at boot time.
> There is a blueprint for that feature that unfortunately didn't make
> it for icehouse.
> https://blueprints.launchpad.net/nova/+spec/schedule-set-availability-zones

That's not at all what I've been talking about.

I'm talking about the concept of EC2 availability zones being improperly
applied in Nova and leading to wrong expectations of the user. Thus, I
am proposing to drop the concept of EC2 AZs in the next major API
version and instead have a general compute node container that may or
may not contain other generic containers of compute nodes.

The HostAggregate concept in Nova was a hack to begin with (it was
originally just XenServer-specific), and then was further hacked to
allow tagging a host aggregate with an AZ -- ostensibly to expose
something to the end user that could be used to direct scheduler hints.

I'm proposing getting rid of the host aggregate hack (or maybe evolving
it?) as well as the availability zone concept and replacing them with a
more flexible generic container object that may be hierarchical in
nature.

Best,
-jay