BZ-1928682: Adding note about the behavior of taints when zone is in partial disruption

Author: bergerhoffer

modules/nodes-scheduler-taints-tolerations-about.adoc

@@ -248,6 +248,10 @@ If you use the `tolerationSeconds` parameter with no value, pods are never evict
 [NOTE]
 ====
 {product-title} evicts pods in a rate-limited way to prevent massive pod evictions in scenarios such as the master becoming partitioned from the nodes.
+
+By default, if more than 55% of nodes in a given zone are unhealthy, the node lifecycle controller changes that zone's state to `PartialDisruption` and the rate of pod evictions is reduced. For small clusters (by default, 50 nodes or less) in this state, nodes in this zone are not tainted and evictions are stopped.
+
+For more information, see link:https://kubernetes.io/docs/concepts/architecture/nodes/#rate-limits-on-eviction[Rate limits on eviction] in the Kubernetes documentation.
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 {product-title} automatically adds a toleration for `node.kubernetes.io/not-ready` and `node.kubernetes.io/unreachable` with `tolerationSeconds=300`, unless the `Pod` configuration specifies either toleration.