# Volume Health Monitoring
LLMS index: [llms.txt](/llms.txt)
---
FEATURE STATE:
Kubernetes v1.21 [alpha]
CSI volume health monitoring allows
CSI Drivers to detect abnormal volume conditions from the underlying storage systems
and report them as events on PVCs
or Pods.
## Volume health monitoring
Kubernetes _volume health monitoring_ is part of how Kubernetes implements the
Container Storage Interface (CSI). Volume health monitoring feature is implemented
in two components: an External Health Monitor controller, and the
kubelet.
If a CSI Driver supports Volume Health Monitoring feature from the controller side,
an event will be reported on the related
PersistentVolumeClaim (PVC)
when an abnormal volume condition is detected on a CSI volume.
The External Health Monitor 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. 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
to use this feature from the node side.