CSI Volume Snapshots and Restore

💡 Quick Answer: Create a VolumeSnapshot referencing a PVC to take a point-in-time backup. Restore by creating a new PVC with dataSource: {kind: VolumeSnapshot, name: my-snapshot}. Requires CSI driver with snapshot support and the snapshot controller installed.

The Problem

You need point-in-time backups of persistent volumes for disaster recovery, pre-upgrade snapshots, or cloning data to new environments — without stopping your application.

The Solution

Prerequisites

# Install snapshot CRDs and controller (if not already present)
kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/master/client/config/crd/snapshot.storage.k8s.io_volumesnapshotclasses.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/master/client/config/crd/snapshot.storage.k8s.io_volumesnapshotcontents.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/master/client/config/crd/snapshot.storage.k8s.io_volumesnapshots.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/master/deploy/kubernetes/snapshot-controller/setup-snapshot-controller.yaml

VolumeSnapshotClass

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshotClass
metadata:
  name: csi-snapclass
  annotations:
    snapshot.storage.kubernetes.io/is-default-class: "true"
driver: ebs.csi.aws.com  # or your CSI driver
deletionPolicy: Delete
parameters:
  # Driver-specific parameters
  encrypted: "true"

Take a Snapshot

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
  name: db-snapshot-20260420
  namespace: production
spec:
  volumeSnapshotClassName: csi-snapclass
  source:
    persistentVolumeClaimName: postgres-data

Restore from Snapshot

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: postgres-data-restored
  namespace: production
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: gp3-encrypted
  resources:
    requests:
      storage: 100Gi
  dataSource:
    name: db-snapshot-20260420
    kind: VolumeSnapshot
    apiGroup: snapshot.storage.k8s.io

Automated Snapshot CronJob

apiVersion: batch/v1
kind: CronJob
metadata:
  name: daily-db-snapshot
  namespace: production
spec:
  schedule: "0 2 * * *"
  jobTemplate:
    spec:
      template:
        spec:
          serviceAccountName: snapshot-creator
          containers:
            - name: snapshot
              image: bitnami/kubectl:1.30
              command:
                - /bin/sh
                - -c
                - |
                  SNAP_NAME="db-snap-$(date +%Y%m%d-%H%M%S)"
                  cat <<EOF | kubectl apply -f -
                  apiVersion: snapshot.storage.k8s.io/v1
                  kind: VolumeSnapshot
                  metadata:
                    name: $SNAP_NAME
                    namespace: production
                    labels:
                      app: postgres
                      type: scheduled
                  spec:
                    volumeSnapshotClassName: csi-snapclass
                    source:
                      persistentVolumeClaimName: postgres-data
                  EOF
                  # Clean up snapshots older than 7 days
                  kubectl get volumesnapshot -n production -l app=postgres \
                    --sort-by=.metadata.creationTimestamp -o name | \
                    head -n -7 | xargs -r kubectl delete -n production
          restartPolicy: OnFailure

Clone a PVC (Without Snapshot)

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: postgres-data-clone
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: gp3-encrypted
  resources:
    requests:
      storage: 100Gi
  dataSource:
    name: postgres-data      # Source PVC
    kind: PersistentVolumeClaim

Verify Snapshot Status

# Check snapshot is ready
kubectl get volumesnapshot db-snapshot-20260420 -o jsonpath='{.status.readyToUse}'
# true

# Check snapshot size
kubectl get volumesnapshot db-snapshot-20260420 -o jsonpath='{.status.restoreSize}'
# 100Gi

# List all snapshots
kubectl get volumesnapshot -A --sort-by=.metadata.creationTimestamp

Common Issues

Best Practices

1. Automate with CronJobs — Schedule daily snapshots for critical data
2. Implement retention — Delete old snapshots to save storage costs
3. Test restores regularly — A snapshot you can’t restore is worthless
4. Label snapshots — Add app, environment, and date labels for management
5. Use deletionPolicy: Retain — For critical snapshots that must survive class deletion

Key Takeaways

• VolumeSnapshot provides native K8s point-in-time backup
• Requires CSI driver support + snapshot controller + CRDs
• Restore creates a new PVC pre-populated with snapshot data
• Automate with CronJobs and implement retention policies
• PVC cloning (dataSource: PVC) works without snapshots but is less flexible