> -----Original Message----- > From: Jay Pipes [mailto:jaypi...@gmail.com] > Sent: 08 April 2014 14:25 > To: openstack-dev@lists.openstack.org > Subject: Re: [openstack-dev] [Nova] Hosts within two Availability Zones : > possible or not ? > > On Tue, 2014-04-08 at 10:49 +0000, Day, Phil wrote: > > On a large cloud you’re protect against this to some extent if the > > number of servers is >> number of instances in the quota. > > > > However it does feel that there are a couple of things missing to > > really provide some better protection: > > > > - A quota value on the maximum size of a server group > > - A policy setting so that the ability to use service-groups > > can be controlled on a per project basis > > Alternately, we could just have the affinity filters serve as weighting > filters > instead of returning NoValidHosts. > > That way, a request containing an affinity hint would cause the scheduler to > prefer placing the new VM near (or not-near) other instances in the server > group, but if no hosts exist that meet that criteria, the filter simply finds > a > host with the most (or fewest, in case of anti-affinity) instances that meet > the affinity criteria. >
I agree that "hint" would be more consistent with weighting that filtering ("constraint" would be a better word for that) - but how does the user get feedback on whether the hint has been honoured or not ? In the case of anti-affinity they would need to: - Create a VM - Check the host hash value is different - if they really care delete the VM and try again ... which is pretty much the same cycle they can do without the hint (the filter/weighter just gives it a better chance of working first time a small system) I would guess that affinity is more likely to be a soft requirement that anti-affinity, in that I can see some services just not meeting their HA goals without anti-affinity but I'm struggling to think of a use case why affinity is a must for the service. _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev