Persistent Volume Claims

• A PersistentVolume (PV) is a cluster-level resource representing a piece of storage provisioned by an administrator.
• A PersistentVolumeClaim (PVC) is a user’s request for storage, specifying capacity, access modes, and optional selectors.

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How PV-PVC Binding Works

• Capacity: PV storage ≥ PVC request
• Access Modes: e.g., ReadWriteOnce, ReadOnlyMany
• Volume Mode: e.g., Filesystem or Block
• Storage Class: must match if specified
• Label Selectors (optional): target specific volumes

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Using Label Selectors

# pvc-selector.yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: myclaim
spec:
  selector:
    matchLabels:
      name: my-pv
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 500Mi

# pv-with-label.yaml
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-vol1
  labels:
    name: my-pv
spec:
  capacity:
    storage: 1Gi
  accessModes:
    - ReadWriteOnce
  awsElasticBlockStore:
    volumeID: <volume-id>
    fsType: ext4

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Step-by-Step: Creating a PersistentVolumeClaim

1. Define the PVC
   Save the following manifest as pvc-definition.yaml:
   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: myclaim
   spec:
     accessModes:
       - ReadWriteOnce
     resources:
       requests:
         storage: 500Mi
   
2. Apply the PVC
   kubectl apply -f pvc-definition.yaml
   
3. Verify Status
   kubectl get pvc myclaim
   
   NAME      STATUS    VOLUME   CAPACITY   ACCESS MODES
   myclaim   Pending
   
   Once a matching PV is available, the PVC transitions to Bound:
   kubectl get pvc myclaim
   
   NAME      STATUS   VOLUME    CAPACITY   ACCESS MODES
   myclaim   Bound    pv-vol1   1Gi        RWO
   

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Reclaim Policies

spec:
  persistentVolumeReclaimPolicy: Delete

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Cleaning Up

kubectl delete pvc myclaim

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Links and References

• Kubernetes Persistent Volumes
• Persistent Volume Claims
• Storage Classes
• AWS Elastic Block Store (EBS)