diff --git a/docs/setup_installation/admin/upgrade.md b/docs/setup_installation/admin/upgrade.md
index c91d0c31c9..1498aac349 100644
--- a/docs/setup_installation/admin/upgrade.md
+++ b/docs/setup_installation/admin/upgrade.md
@@ -239,6 +239,17 @@ From 5.3 the default is 2048, up from 1024, because at 1 GiB the sidecar was OOM
   While the sidecar restarts, the pod reports `Ready=False` and leaves the endpoints of its service, so the agent, healthy and still running, receives no requests.
   Looking for agent restarts finds none.
 
+### MinIO priority class and registry probes { #upgrade-minio-priority }
+
+- `minio.priorityClassName` sets a priority class on the MinIO StatefulSet; it is empty by default.
+  On a cluster where MinIO keeps its data on a node-local volume, `system-cluster-critical` keeps the kubelet's eviction manager from evicting it under disk pressure, where evicting it frees no disk.
+- The registry's liveness probe checks that the process answers, and its readiness probe keeps `/v2/`.
+  While MinIO is unavailable the registry pods leave the service instead of restarting, and image pulls fail until MinIO is back.
+  The registry pods are recreated by the upgrade.
+- The registry no longer logs its S3 requests (`REGISTRY_STORAGE_S3_LOGLEVEL` is `off`).
+- A new Prometheus alert, `NodeRootFilesystemLow` (warning), fires when a node's root filesystem has less than 15% free for 10 minutes.
+  It is only rendered when `prometheus-node-exporter.enabled` is true.
+
 ## Changes from 5.2.2 { #upgrade-changes-from-522 }
 
 These changes ship in 5.2.2 and 5.3.0.