Bug 1537150

1. Proposed title of this feature request
Add support for multi-zone PVs when using Cinder volumes through OpenStack cloud provider.

3. What is the nature and description of the request?
 As a I user I would like to be have support for multi zone PVs when using Cinder volumes through OpenStack cloud provider.

At this time it's only possible to run pods attached to Cinder volumes when the Cinder availability zone matches Nova availability zones that the compute nodes are deployed into.
In case a storage backend like Ceph is used, there is no concept of availability zones within OpenStack region for Cinder, hence although it's a valid configuration for OpenStack it doesn't seem to work on OCP 3.6 when NoVolumeZoneConflict predicate is evaluated, producing a "No nodes are available that match all of the following predicates:: NoVolumeZoneConflict" error event.

4. Why does the customer need this? (List the business requirements here)
 Because as explained above in case a storage backend like Ceph (doesn't have the concept of availability zones within the OpenStack region for Cinder) volume will either fail to be created or it will be created but never attached to an instance in OpenStack.

5. How would the customer like to achieve this? (List the functional requirements here)
Be able to handle multi-zones PVs for Cinder volumes.

6. For each functional requirement listed in question 5, specify how Red Hat and the customer can test to confirm the requirement is successfully implemented.
Once scheduler predicate NoVolumeZoneConflict is modified in such a way that allows multi-zones PVs to be paired when using Cinder volumes.

10. List any affected packages or components.
OpenShift/Kubernetes scheduler

Additional info:

There is an upstream issue similar to customer requirements at: https://github.com/kubernetes/kubernetes/issues/51232 and this has been addressed for GCE at https://github.com/kubernetes/kubernetes/pull/51667