What Are Volume Snapshots in Kubernetes?

Detailed Answer

Volume snapshots provide a standardized way to create point-in-time copies of Persistent Volumes in Kubernetes. They are part of the CSI (Container Storage Interface) specification and work with any CSI driver that supports snapshotting.

The Snapshot Object Model

The snapshot API mirrors the familiar PV/PVC model:

| Storage | Snapshot | |---------|----------| | StorageClass | VolumeSnapshotClass | | PersistentVolume (PV) | VolumeSnapshotContent | | PersistentVolumeClaim (PVC) | VolumeSnapshot |

Prerequisites

1. A CSI driver that supports snapshots (e.g., aws-ebs-csi-driver, csi-driver-nfs, portworx)
2. The snapshot controller and CRDs installed (not included by default)

# Install snapshot CRDs and controller
kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/master/client/config/crd/
kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/master/deploy/kubernetes/snapshot-controller/

Creating a VolumeSnapshotClass

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshotClass
metadata:
  name: ebs-snapshot-class
driver: ebs.csi.aws.com
deletionPolicy: Retain
parameters:
  # Driver-specific parameters
  type: "standard"

deletionPolicy:

• Delete: Deletes the underlying snapshot when the VolumeSnapshot is deleted
• Retain: Keeps the snapshot even after the VolumeSnapshot object is deleted

Taking a Snapshot

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
  name: db-snapshot-2026-03-19
  namespace: production
spec:
  volumeSnapshotClassName: ebs-snapshot-class
  source:
    persistentVolumeClaimName: postgres-data

# Check snapshot status
kubectl get volumesnapshot db-snapshot-2026-03-19 -n production
# NAME                      READYTOUSE   RESTORESIZE   AGE
# db-snapshot-2026-03-19    true         50Gi          30s

Restoring from a Snapshot

Create a new PVC with the snapshot as the data source:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: postgres-data-restored
  namespace: production
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: gp3
  resources:
    requests:
      storage: 50Gi
  dataSource:
    name: db-snapshot-2026-03-19
    kind: VolumeSnapshot
    apiGroup: snapshot.storage.k8s.io

The CSI driver creates a new volume pre-populated with the snapshot data. Mount this PVC in a Pod to access the restored data.

Cloning Volumes

You can also clone a PVC directly (without an intermediate snapshot) using the PVC as a data source:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: postgres-data-clone
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: gp3
  resources:
    requests:
      storage: 50Gi
  dataSource:
    name: postgres-data        # Source PVC
    kind: PersistentVolumeClaim

Scheduled Snapshots with CronJobs

Automate periodic snapshots with a CronJob:

apiVersion: batch/v1
kind: CronJob
metadata:
  name: daily-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
                - |
                  DATE=$(date +%Y-%m-%d)
                  cat <<EOF | kubectl apply -f -
                  apiVersion: snapshot.storage.k8s.io/v1
                  kind: VolumeSnapshot
                  metadata:
                    name: db-snapshot-${DATE}
                    namespace: production
                  spec:
                    volumeSnapshotClassName: ebs-snapshot-class
                    source:
                      persistentVolumeClaimName: postgres-data
                  EOF
              resources:
                requests:
                  cpu: "50m"
                  memory: "64Mi"
          restartPolicy: OnFailure

Snapshot Lifecycle

PVC (source) → VolumeSnapshot (user request)
                    ↓
              VolumeSnapshotContent (actual snapshot)
                    ↓
              New PVC (restore from dataSource)
                    ↓
              New PV (provisioned by CSI driver)

Limitations and Considerations

1. Crash-consistent only: Snapshots capture disk state, not application state. Databases should be quiesced first.
2. Same storage class: Restored PVCs typically must use the same storage backend as the source.
3. Cross-namespace: VolumeSnapshots are namespace-scoped. Use VolumeSnapshotContent for cross-namespace sharing.
4. Cost: Cloud provider snapshots incur storage costs. Implement a retention policy.
5. Not a backup solution: Snapshots are typically stored in the same region/storage system. Use cross-region replication for disaster recovery.

Verifying Snapshot Support

# Check if your CSI driver supports snapshots
kubectl get csidriver -o jsonpath='{range .items[*]}{.metadata.name}: snapshotting={.spec.volumeLifecycleModes}{"\n"}{end}'

# List VolumeSnapshotClasses
kubectl get volumesnapshotclass

# Check snapshot status
kubectl describe volumesnapshot db-snapshot-2026-03-19