Open Stack

> From: Duncan Thomas [mailto:duncan.thomas at gmail.com]
> Sent: Friday, August 28, 2015 2:31 PM
> 
> Except your failure domain includes the cinder volume service, independent
> of the resiliency of you backend, so if they're all on one node then you don't
> really have availability zones.
> 
> I have historically strongly espoused the same view as Ben, though there are
> lots of people who want fake availability zones... No strong use cases though

In case you have Ceph backend (actually I think this applies to any non-LVM backend), you normally run c-vol on your controller nodes in A/P manner. c-vol becomes more like control plane service and we don't provide AZs for control plane. Nova doesn't do it either, AZs are only for compute nodes.

Given that now Nova assumes that Cinder have same set of AZs, we should be able to create fake ones (or have a fallback option like in patch provided by Ned).