openstack team mailing list archive

[Armando Migliaccio <amigliaccio@xxxxxxxxxxxx>]

On Tue, Apr 3, 2012 at 7:10 PM, Vishvananda Ishaya
<vishvananda@xxxxxxxxx> wrote:
>
> On Apr 3, 2012, at 6:45 AM, Day, Phil wrote:
>
> Hi John,
>
> Maybe the problem with host aggregates is that it too quickly became
> something that was linked to hypervisor capability, rather than being the
> more general mechanism of which one form of aggregate could be linked to
> hypervisor capabilities ?

The host aggregate model is not tied to no hypervisor-dependent
detail, it's a group of hosts with metadata linked to it. As far as
the the functionality around it, that can evolve to make it work as
you expected it to work. If I understand it correctly, you'd not be
interested in xenapi (whose implementation is wrapped around the
concept of pool), and as far as KVM is concerned, this is still a
blank canvas.

As for the scheduler, as most things in Nova, you can write a new one
(that's host-aggregate aware), or you can extend an existing one to
make sure it understands the metadata related to a host belonging to
an aggregate. The latter, in particular,  was not done in the Essex
timeframe for lack of time ;(

>
> Should we have a “host aggregates 2.0” session at the Design Summit ?
>

I am all in for a "host aggregate 2.0" so to speak, or just the
continuation of the work that was started; at first I got the
impression that we were going to write new abstraction/functionality
from scratch just because the one that already existed did not fit the
bill...I am glad I was wrong :)

>
> + 1
>
> I think the primary use case is associating metadata with groups of hosts
> that can be interpreted by the scheduler.  Obviously, this same metadata can
> be used to create pools/etc. in the hypervisor, but we can't forget about
> the scheduler.  Modifying flags on the hosts for capabilities is ugly.
>
> Vish
>
>
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