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On 07/03/2014 01:53 PM, Sylvain Bauza wrote:
> Hi,
> 
> ==
> tl; dr: A decision has been made to split out the scheduler to a
> separate project not on a feature parity basis with nova-scheduler, your
> comments are welcome.
> ==

...

> During the last Gantt meeting held Tuesday, we discussed about the
> status and the problems we have. As we are close to Juno-2, there are
> some concerns about which blueprints would be implemented by Juno, so
> Gantt would be updated after. Due to the problems raised in the
> different blueprints (please see the links there), it has been agreed to
> follow a path a bit different from the one agreed at the Summit : once
> B/ is merged, Gantt will be updated and work will happen in there while
> work with C/ will happen in parallel. That means we need to backport in
> Gantt all changes happening to the scheduler, but (and this is the most
> important point) until C/ is merged into Gantt, Gantt won't support
> filters which decide on aggregates or instance groups. In other words,
> until C/ happens (but also A/), Gantt won't be feature-parity with
> Nova-scheduler.
> 
> That doesn't mean Gantt will move forward and leave all missing features
> out of it, we will be dedicated to feature-parity as top priority but
> that implies that the first releases of Gantt will be experimental and
> considered for testing purposes only.

I don't think this sounds like the best approach.  It sounds like effort
will go into maintaining two schedulers instead of continuing to focus
effort on the refactoring necessary to decouple the scheduler from Nova.
 It's heading straight for a "nova-network and Neutron" scenario, where
we're maintaining both for much longer than we want to.

I strongly prefer not starting a split until it's clear that the switch
to the new scheduler can be done as quickly as possible.  That means
that we should be able to start a deprecation and removal timer on
nova-scheduler.  Proceeding with a split now will only make it take even
longer to get there, IMO.

This was the primary reason the last gantt split was scraped.  I don't
understand why we'd go at it again without finishing the job first.

-- 
Russell Bryant