Skip to main content

StatefulSet With One PVC Per Pod

The official StatefulSet example is curvine-csi/examples/statefulset-curvine.yaml in the Curvine source tree.

Use this pattern when each replica needs its own persistent directory instead of sharing one PVC.

Example Resources​

The example creates:

  • Service/curvine-service
  • StatefulSet/curvine-statefulset
  • namespace curvine-system
  • 3 replicas
  • volumeClaimTemplates entry named data
  • storageClassName: curvine-sc
  • per-pod mount path /usr/share/nginx/html

Apply The Example​

kubectl apply -f curvine-csi/examples/statefulset-curvine.yaml

What Happens​

  • Kubernetes creates one PVC per pod from volumeClaimTemplates.
  • Each pod writes its hostname, timestamp, and PVC name into index.html.
  • The CSI controller dynamically provisions a Curvine directory for each PVC.
  • The CSI node plugin mounts each PVC into the matching pod.

Because each PVC is distinct, each pod gets independent application data even though all of them use the same CSI driver and StorageClass.

Verify PVC Separation​

kubectl get statefulset -n curvine-system curvine-statefulset
kubectl get pods -n curvine-system -l app=curvine-stateful
kubectl get pvc -n curvine-system

Check the rendered content inside each replica:

for pod in curvine-statefulset-0 curvine-statefulset-1 curvine-statefulset-2; do
  echo "=== $pod ==="
  kubectl exec -n curvine-system "$pod" -- cat /usr/share/nginx/html/index.html
done

The output should differ by pod hostname and PVC name.

Check Persistence​

kubectl exec -n curvine-system curvine-statefulset-0 -- sh -c 'echo retained >> /usr/share/nginx/html/index.html'
kubectl delete pod -n curvine-system curvine-statefulset-0
kubectl wait -n curvine-system --for=condition=Ready pod/curvine-statefulset-0 --timeout=120s
kubectl exec -n curvine-system curvine-statefulset-0 -- grep retained /usr/share/nginx/html/index.html

If retained is still present after the pod is recreated, the StatefulSet is correctly reusing the original PVC.

Notes​

  • The example uses ReadWriteOnce in volumeClaimTemplates, which matches the common StatefulSet pattern of one writer per replica.
  • The dynamically created Curvine directory is still derived from the StorageClass fs-path plus the generated PV name, not from the pod ordinal directly.
  • FUSE reuse still happens at the node level based on master-addrs + fs-path; the pod-level data isolation comes from the subdirectory that each PVC points to.