Skip to main content

Persistent Volumes

Persistent Volumes (PV) and Persistent Volume Claims (PVC) provide a way for Pods to use durable storage that persists beyond the Pod lifecycle.

  • PersistentVolume (PV): a piece of storage provisioned by an administrator or dynamically via a StorageClass
  • PersistentVolumeClaim (PVC): a request for storage by a user; binds to a PV that satisfies the claim
More Information

PersistentVolume Example​

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

PersistentVolumeClaim Example​

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-pvc
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi

Using a PVC in a Pod​

spec:
  containers:
  - name: app
    image: my-app:latest
    volumeMounts:
    - name: data
      mountPath: /app/data
  volumes:
  - name: data
    persistentVolumeClaim:
      claimName: my-pvc

Access Modes​

  • ReadWriteOnce (RWO): the volume can be mounted as read-write by a single node
  • ReadOnlyMany (ROX): the volume can be mounted as read-only by many nodes
  • ReadWriteMany (RWX): the volume can be mounted as read-write by many nodes
  • ReadWriteOncePod (RWOP): the volume can be mounted as read-write by a single Pod

Reclaim Policies​

  • Retain: the PV is kept after the PVC is deleted; data must be manually cleaned up
  • Delete: the PV and its underlying storage are deleted when the PVC is deleted
  • Recycle (deprecated): basic scrub (rm -rf /volume/*) before making the PV available again

StorageClasses​

  • Enable dynamic provisioning of PVs
  • When a PVC requests a StorageClass, the provisioner automatically creates a PV
  • Eliminates the need for administrators to pre-provision PVs
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: fast
provisioner: kubernetes.io/aws-ebs
parameters:
  type: gp3
reclaimPolicy: Delete

A PVC can request a specific StorageClass:

spec:
  storageClassName: fast
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 20Gi
More Information