clarified single-az cluster minimum infra nodes

 Author:    Josephine Pfeiffer <[email protected]>
 Date:      Wed Feb 22 13:37:03 2023 +0100
 On branch rosa-az-nodes
 Changes to be committed:
	modified:   modules/rosa-policy-failure-points.adoc

Author: pfeifferj

modules/rosa-policy-failure-points.adoc

@@ -35,7 +35,9 @@ When accounting for possible node failures, it is also important to understand h
 
 [id="rosa-policy-container-cluster-failure_{context}"]
 == Cluster failure
-ROSA clusters have at least three control plane nodes and three infrastructure nodes that are preconfigured for high availability, either in a single zone or across multiple zones, depending on the type of cluster you have selected. Control plane and infrastructure nodes have the same resiliency as worker nodes, with the added benefit of being managed completely by Red Hat.
+Single-AZ ROSA clusters have at least three control plane and two infrastructure nodes in the same availability zone (AZ) in the private subnet.
+
+Multi-AZ ROSA clusters have at least three control plane nodes and three infrastructure nodes that are preconfigured for high availability, either in a single zone or across multiple zones, depending on the type of cluster you have selected. Control plane and infrastructure nodes have the same resiliency as worker nodes, with the added benefit of being managed completely by Red Hat.
 
 In the event of a complete control plane outage, the OpenShift APIs will not function, and existing worker node pods are unaffected. However, if there is also a pod or node outage at the same time, the control planes must recover before new pods or nodes can be added or scheduled.