Merge pull request #63960 from EricPonvelle/OSDOCS-6922_InfraNode_Scaling

OSDOCS-6922: Infrastructure Node Utilization Update

Author: EricPonvelle

modules/sd-planning-considerations.adoc

@@ -70,10 +70,10 @@ The maximum number of compute nodes on ROSA is 180.
 
 .Rules for infrastructure node resizing alerts
 
-Resizing alerts are triggered for the infrastructure nodes in a cluster when either of the following scenarios are true: 
+Resizing alerts are triggered for the infrastructure nodes in a cluster when it has high-sustained CPU or memory utilization. This high-sustained utilization status is: 
 
-* Each infrastructure node has less than 16GiB RAM or less than 5 CPUs, and there are more than 25 and less than 101 compute nodes.
-* Each infrastructure node has less than 32GiB RAM or less than 9 CPUs, and there are more than 100 compute nodes.
+* Infrastructure nodes sustain over 50% utilization on average in a classic ROSA cluster with a single availability zone using 2 infrastructure nodes.
+* Infrastructure nodes sustain over 66% utilization on average in a classic ROSA cluster with multiple availability zones using 3 infrastructure nodes.
 +
 [NOTE]
 ====
@@ -85,6 +85,8 @@ ifdef::openshift-dedicated[]
 {product-title} 
 endif::[]
 is 180.
+
+The resizing alerts only appear after sustained periods of high utilization. Short usage spikes, such as a node temporarily going down causing the other node to scale up, do not trigger these alerts.
 ====
 
 The SRE team might scale the control plane and infrastructure nodes for additional reasons, for example to manage an increase in resource consumption on the nodes.