[openstack-dev] [ptl][tc] Accessible upgrade support

Graham Hayes gr at ham.ie
Thu Oct 5 11:08:53 UTC 2017



On Thu, 5 Oct 2017, at 09:50, Thierry Carrez wrote:
> Matt Riedemann wrote:
> > What's the difference between this tag and the zero-impact-upgrades tag?
> > I guess the accessible one is, can a user still ssh into their VM while
> > the nova compute service is being upgraded. The zero-impact-upgrade one
> > is more to do with performance degradation during an upgrade. I'm not
> > entirely sure what that might look like, probably need operator input.
> > For example, while upgrading, you're live migrating VMs all over the
> > place which is putting extra strain on the network.
> 
> The zero-impact-upgrade tag means no API downtime and no measurable
> impact on performance, while the accessible-upgrade means that while
> there can be API downtime, the resources provisioned are still
> accessible (you can use the VM even if nova-api is down).
> 
> I still think we have too many of those upgrade tags, and amount of
> information they provide does not compensate the confusion they create.
> If you're not clear on what they mean, imagine a new user looking at the
> Software Navigator...
> 
> In particular, we created two paths in the graph:
> * upgrade < accessible-upgrade
> * upgrade < rolling-upgrade < zero-downtime < zero-impact
> 
> I personally would get rid of zero-impact (not sure there is that much
> additional information it conveys beyond zero-downtime).
> 
> If we could make the requirements of accessible-upgrade a part of
> rolling-upgrade, that would also help (single path in the graph, only 3
> "levels"). Is there any of the current rolling-upgrade things (cinder,
> neutron, nova, swift) that would not qualify for accessible-upgrade as
> well ?

Well, there is projects (like designate) that qualify for accessible
upgrade, but not rolling upgrade.

> 
> -- 
> Thierry Carrez (ttx)
> 
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