KubePvcCritical: what to do when it fires

Alert rule

alert: KubePvcCritical
expr: kubelet_volume_stats_available_bytes
  / kubelet_volume_stats_capacity_bytes * 100 < 5
and kubelet_volume_stats_capacity_bytes > 0
for: 5m
severity: critical

Alert message: PVC {{ $labels.namespace }}/{{ $labels.persistentvolumeclaim }} is almost full

What it means

Less than 5% is free on a PVC volume. The application is about to be unable to write data.

Common causes

The same as for KubePvcAlmostFull, but the headroom is used up.

Diagnostics

kubectl -n <ns> exec <pod> -- df -h <mount-path>
kubectl -n <ns> exec <pod> -- du -xh --max-depth=2 <mount-path>
kubectl -n <ns> get pvc <name> -o yaml | grep -i -E 'storageClassName|storage:'
kubectl get storageclass <name> -o jsonpath='{.allowVolumeExpansion}'

How to fix

Urgently expand the PVC or free space. For databases, do not delete data files by hand — use the database's own mechanisms (WAL/binlog cleanup, VACUUM and the like).

When it is OK to silence

Not until space has been freed.

Related alerts

• KubePvcAlmostFull
• KubeNodeNotReady
• KubeNodePressure
• KubeJobFailed
• KubeHpaMaxedOut

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