Merge pull request #32683 from fengzixu/main

doc: update volume health monitoring doc with metrics content

Author: k8s-ci-robot

content/en/docs/concepts/storage/volume-health-monitoring.md

@@ -24,7 +24,7 @@ If a CSI Driver supports Volume Health Monitoring feature from the controller si
 
 The External Health Monitor {{< glossary_tooltip text="controller" term_id="controller" >}} also watches for node failure events. You can enable node failure monitoring by setting the `enable-node-watcher` flag to true. When the external health monitor detects a node failure event, the controller reports an Event will be reported on the PVC to indicate that pods using this PVC are on a failed node.
 
-If a CSI Driver supports Volume Health Monitoring feature from the node side, an Event will be reported on every Pod using the PVC when an abnormal volume condition is detected on a CSI volume.
+If a CSI Driver supports Volume Health Monitoring feature from the node side, an Event will be reported on every Pod using the PVC when an abnormal volume condition is detected on a CSI volume. In addition, Volume Health information is exposed as Kubelet VolumeStats metrics. A new metric kubelet_volume_stats_health_status_abnormal is added. This metric includes two labels: `namespace` and `persistentvolumeclaim`. The count is either 1 or 0. 1 indicates the volume is unhealthy, 0 indicates volume is healthy. For more information, please check [KEP](https://github.com/kubernetes/enhancements/tree/master/keps/sig-storage/1432-volume-health-monitor#kubelet-metrics-changes).
 
 {{< note >}}
 You need to enable the `CSIVolumeHealth` [feature gate](/docs/reference/command-line-tools-reference/feature-gates/) to use this feature from the node side.