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PersistentVolumeClaim vs emptyDir

Hands-on example​

Assume:

  • A working Kubernetes cluster
  • A default StorageClass exists
  • kubectl is configured

Initial state​

No Pods or PVCs exist.

kubectl get pods
kubectl get pvc
No resources found in default namespace.
No resources found in default namespace.

Step 1: Use emptyDir storage​

Create a Pod with emptyDir.

kubectl apply -f - <<EOF
apiVersion: v1
kind: Pod
metadata:
  name: emptydir-demo
spec:
  containers:
  - name: app
    image: busybox
    command: ["sh", "-c", "echo data > /data/file && sleep 3600"]
    volumeMounts:
    - name: tmp
      mountPath: /data
  volumes:
  - name: tmp
    emptyDir: {}
EOF
pod/emptydir-demo created

Verify data.

kubectl exec emptydir-demo -- cat /data/file
data

Delete the Pod.

kubectl delete pod emptydir-demo
pod "emptydir-demo" deleted

Recreate the same Pod.

kubectl apply -f - <<EOF
apiVersion: v1
kind: Pod
metadata:
  name: emptydir-demo
spec:
  containers:
  - name: app
    image: busybox
    command: ["sh", "-c", "ls /data || true"]
    volumeMounts:
    - name: tmp
      mountPath: /data
  volumes:
  - name: tmp
    emptyDir: {}
EOF
pod/emptydir-demo created

Check contents.

kubectl logs emptydir-demo
ls: /data: No such file or directory

What changed:

  • Data was lost

What did not change:

  • Pod spec stayed the same

Step 2: Use PersistentVolumeClaim storage​

Create a PVC.

kubectl apply -f - <<EOF
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-demo
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
EOF
persistentvolumeclaim/pvc-demo created

Create a Pod using the PVC.

kubectl apply -f - <<EOF
apiVersion: v1
kind: Pod
metadata:
  name: pvc-pod
spec:
  containers:
  - name: app
    image: busybox
    command: ["sh", "-c", "echo data > /data/file && sleep 3600"]
    volumeMounts:
    - name: data
      mountPath: /data
  volumes:
  - name: data
    persistentVolumeClaim:
      claimName: pvc-demo
EOF
pod/pvc-pod created

Verify data.

kubectl exec pvc-pod -- cat /data/file
data

Delete the Pod.

kubectl delete pod pvc-pod
pod "pvc-pod" deleted

Recreate it.

kubectl apply -f - <<EOF
apiVersion: v1
kind: Pod
metadata:
  name: pvc-pod
spec:
  containers:
  - name: app
    image: busybox
    command: ["sh", "-c", "cat /data/file"]
    volumeMounts:
    - name: data
      mountPath: /data
  volumes:
  - name: data
    persistentVolumeClaim:
      claimName: pvc-demo
EOF
pod/pvc-pod created

Check logs.

kubectl logs pvc-pod
data

Key observation​

  • emptyDir is Pod-scoped and disposable
  • PVC-backed storage survives Pod deletion