Customers expect to be able to configure PVCs for cluster monitoring as per the openshift documentation (https://docs.openshift.com/container-platform/4.6/monitoring/configuring-the-monitoring-stack.html#configuring-persistent-storage) however ARO actively deletes PVC configurations when set.

See https://github.com/Azure/ARO-RP/issues/1454 for an example request and commentary

While there are some known issues with storage being locked to an AZ, there are ways to ensure Kubernetes does not try to create a POD with pvc settings in a wrong AZ (https://kubernetes.io/docs/setup/best-practices/multiple-zones/#storage-access-for-zones) which means there should only be a problem if the whole AZ is evacuated and thus no pod can be scheduled there, which would be an unusual issue.

Secondarily ROSA and OSD on AWS clusters support PVCs (even with the same PVC / AZ pinning) so a customer working with Hybrid clouds will have a different experience.

If we absolutely cannot enable PVCs, we should provide documentation as to why so that customer's aren't tricked by the OCP docs into thinking it should be supported. We should also use an AdmissionController to restrict their ability to add PVCs to the cluster-monitoring-config configMap to restrict them from making the change instead of silently reverting their changes.