Add general guideline for control plane node scaling

Relates: OCP-840

docs/modules/ROOT/pages/references/cp_node_scaling.adoc

@@ -0,0 +1,42 @@
+= Control Plane Node Scaling
+
+The control plane node resource requirements depent on a number of different metrics.
+CPU requirements generally depend on the ammount on API write requests,
+while memory requirements generally depend on the amount of resource objects (most importantly Pod count) in the cluster.
+
+To avoid cascading failures during a scheduled node reboot or an unexpected node failure,
+it's recommended to keep the overall CPU and memory usage not significantly higher than 60%.
+
+The following guiedlines are an estimate, based on metrics collected from our managed clusters.
+Individual clusters may vary depending on worker node size and individual workload running on the cluster.
+
+[cols="1,1"]
+|===
+| Control Plane Spec  | Cluster Parameters
+
+| 4 CPU
+
+16Gi Memory
+
+| Small Cluster
+
+max. 3 Worker Nodes
+
+
+| 4 CPU
+
+24Gi Memory
+
+| Small Cluster
+
+more than 500 Pods
+
+
+| 4 CPU
+
+32Gi Memory
+
+| Medium Cluster
+
+more than 1000 Pods
+|===

docs/modules/ROOT/partials/nav.adoc

@@ -237,6 +237,7 @@
 ** xref:oc4:ROOT:references/annotations.adoc[]
 ** xref:oc4:ROOT:references/labels.adoc[]
 ** xref:oc4:ROOT:references/projectsyn/developer.adoc[]
+** xref:oc4:ROOT:references/cp_node_scaling.adoc[]
 
 * Decisions
 ** xref:oc4:ROOT:explanations/decisions/machine-api.adoc[]