Sign In

Curriculum 17: Storage & Volumes

Persistent Volumes

15 min · 25 XP

Persistent Volumes

A PersistentVolume (PV) is a cluster-level storage resource provisioned by an administrator or dynamically via a StorageClass. PVs have a lifecycle independent of any pod, meaning data persists even when pods are deleted.

Creating a Persistent Volume

apiVersion: v1
kind: PersistentVolume
metadata:
  name: data-pv
spec:
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  storageClassName: standard
  hostPath:
    path: /mnt/data

kubectl apply -f pv.yaml
kubectl get pv data-pv

Access Modes

PVs support three access modes depending on the storage backend:

  • ReadWriteOnce (RWO) -- mounted as read-write by a single node
  • ReadOnlyMany (ROX) -- mounted as read-only by multiple nodes
  • ReadWriteMany (RWX) -- mounted as read-write by multiple nodes
kubectl get pv -o custom-columns=NAME:.metadata.name,ACCESS:.spec.accessModes,CAPACITY:.spec.capacity.storage

Reclaim Policies

When a PVC releases a PV, the reclaim policy determines what happens:

  • Retain -- keeps the PV and its data; requires manual cleanup
  • Delete -- removes the PV and its underlying storage
  • Recycle -- performs a basic scrub (deprecated in favor of dynamic provisioning)

Checking PV Status

kubectl get pv
kubectl describe pv data-pv

PV status progresses through: Available (not yet bound), Bound (claimed by a PVC), Released (PVC deleted but not yet reclaimed), and Failed (automatic reclamation failed). Understanding these states helps troubleshoot storage issues.