Working with Volume Snapshots

1. Installing VolumeSnapshot CRDs

Resource	Description	Installation Method	Notes
VolumeSnapshotClass	Defines a class of snapshot storage with parameters for provisioning snapshots	`kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v6.2.0/client/config/crd/snapshot.storage.k8s.io_volumesnapshotclasses.yaml`	Required for snapshot creation
VolumeSnapshot	Represents a snapshot of a volume to be created or restored from	`kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v6.2.0/client/config/crd/snapshot.storage.k8s.io_volumesnapshots.yaml`	Used to request a snapshot of a PersistentVolumeClaim
VolumeSnapshotContent	Represents a snapshot that has been created in the storage backend	`kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v6.2.0/client/config/crd/snapshot.storage.k8s.io_volumesnapshotcontents.yaml`	Created by the CSI driver when a snapshot is taken

Example: Apply VolumeSnapshot CRDs

kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v6.2.0/client/config/crd/snapshot.storage.k8s.io_volumesnapshotclasses.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v6.2.0/client/config/crd/snapshot.storage.k8s.io_volumesnapshots.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v6.2.0/client/config/crd/snapshot.storage.k8s.io_volumesnapshotcontents.yaml

Note: Ensure that the CSI driver supports volume snapshots before applying these CRDs.

2. Creating VolumeSnapshotClass

Field	Description	Required	Example Value
apiVersion	API version of the VolumeSnapshotClass resource	Yes	`snapshot.storage.k8s.io/v1`
kind	Kind of the Kubernetes resource	Yes	`VolumeSnapshotClass`
metadata.name	Name of the VolumeSnapshotClass	Yes	`fast-ssd-snapshot-class`
driver	CSI driver name that handles snapshots for this class	Yes	`aws-ebs.csi.aws.com`
deletionPolicy	Policy for handling snapshots when the VolumeSnapshot is deleted	Yes	`Retain` or `Delete`
parameters	Driver-specific parameters for snapshot creation	No	`{ "type": "gp2" }`

Example: VolumeSnapshotClass YAML Definition

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshotClass
metadata:
  name: fast-ssd-snapshot-class
driver: aws-ebs.csi.aws.com
deletionPolicy: Retain
parameters:
  type: gp2

Note: The deletionPolicy field determines whether the actual snapshot in the storage backend is deleted when the Kubernetes VolumeSnapshot object is deleted. Retain keeps the snapshot, while Delete deletes it.

3. Creating VolumeSnapshot

Field	Description	Required	Example Value
apiVersion	API version of the VolumeSnapshot resource	Yes	`snapshot.storage.k8s.io/v1`
kind	Kind of the resource (must be VolumeSnapshot)	Yes	`VolumeSnapshot`
metadata.name	Name of the VolumeSnapshot	Yes	`my-snapshot`
spec.source	Source of the VolumeSnapshot (PersistentVolumeClaim or VolumeSnapshotContent)	Yes	`{ "persistentVolumeClaimName": "my-pvc" }`
spec.volumeSnapshotClassName	Name of the VolumeSnapshotClass to use for creating the snapshot	No	`my-snapshot-class`

Example: Creating a VolumeSnapshot from a PVC

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
  name: my-snapshot
spec:
  source:
    persistentVolumeClaimName: my-pvc

Note: The VolumeSnapshot must reference a valid PersistentVolumeClaim that supports snapshots.

4. Listing VolumeSnapshots

Field	Description	Example Value
apiVersion	API version of the VolumeSnapshot resource	`snapshot.storage.k8s.io/v1`
kind	Kind of the resource (must be VolumeSnapshot)	`VolumeSnapshot`
metadata.name	Name of the VolumeSnapshot	`my-snapshot`
spec.source.persistentVolumeClaimName	Name of the PVC from which the snapshot is created	`my-pvc`
status.readyToUse	Indicates whether the snapshot is ready to use	`true`
status.restoreSize	Size of the volume when restored from this snapshot	`10Gi`

Example: Listing VolumeSnapshots using kubectl

kubectl get volumesnapshots

Example: Listing VolumeSnapshots with details using kubectl

kubectl get volumesnapshots -o wide

Example: Listing VolumeSnapshots in a specific namespace

kubectl get volumesnapshots -n my-namespace

5. Describing VolumeSnapshot Details

Field	Description	Example Value
apiVersion	The API version of the VolumeSnapshot resource	`snapshot.storage.k8s.io/v1`
kind	The type of the Kubernetes resource	`VolumeSnapshot`
metadata.name	The name of the VolumeSnapshot resource	`my-snapshot`
metadata.namespace	The namespace where the VolumeSnapshot is created	`default`
spec.source.volumeSnapshotContentName	The name of the VolumeSnapshotContent that this snapshot references	`snapshot-content-12345`
status.boundVolumeSnapshotContentName	The name of the VolumeSnapshotContent that this snapshot is bound to	`snapshot-content-12345`
status.createtime	The timestamp when the VolumeSnapshot was created	`2025-04-05T10:00:00Z`
status.readyToUse	Indicates whether the snapshot is ready to be used	`true`
status.restoreSize	The size of the volume that was snapshotted	`10Gi`

Example: Describe VolumeSnapshot in YAML

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
  name: my-snapshot
  namespace: default
spec:
  source:
    volumeSnapshotContentName: snapshot-content-12345
status:
  boundVolumeSnapshotContentName: snapshot-content-12345
  createtime: "2025-04-05T10:00:00Z"
  readyToUse: true
  restoreSize: "10Gi"

Example: Describe VolumeSnapshot using kubectl

kubectl describe volumesnapshot my-snapshot

6. Restoring PVC from Snapshot

Field	Description	Example Value
apiVersion	API version of the VolumeSnapshotContent resource	`snapshot.storage.k8s.io/v1`
kind	Kind of the resource	`VolumeSnapshotContent`
metadata.name	Name of the VolumeSnapshotContent	`snapshot-content-1`
spec.source.volumeSnapshotContentName	Name of the VolumeSnapshotContent to restore from	`snapshot-content-1`
spec.volumeSnapshotRef.name	Name of the VolumeSnapshot object	`my-snapshot`

Example: Restoring PVC from VolumeSnapshot

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshotContent
metadata:
  name: snapshot-content-1
spec:
  source:
    volumeSnapshotContentName: snapshot-content-1
  volumeSnapshotRef:
    name: my-snapshot

Note: Ensure that the VolumeSnapshotContent is compatible with the storage class used by the PVC.

Warning: Restoring from a snapshot may result in data loss if the original PVC was modified after the snapshot was created.

7. Configuring Snapshot Deletion Policy

Policy	Description	Configuration	Notes
retention	Number of snapshots to retain	`10`	Applies to all volumes in the namespace
autoDelete	Automatically delete oldest snapshots	`true`	When retention limit is exceeded
schedule	Cron expression for snapshot creation	`0 0 * * *`	Runs daily at midnight

Example: Snapshot Deletion Policy Configuration

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshotClass
metadata:
  name: example-snapshot-class
deletionPolicy: Retain
parameters:
  retention: "5"
  autoDelete: "true"
  schedule: "0 0 * * *"

Note: The deletionPolicy field controls whether snapshots are deleted when the VolumeSnapshot is deleted.

Warning: Setting autoDelete to true can lead to data loss if not properly configured.

8. Using Snapshot with CSI Drivers

Property	Description	Values	Notes
driver	CSI driver name	`aws-ebs.csi.aws.com`	Must be registered in the cluster
snapshotHandle	Unique identifier for the snapshot	`snapshot-1234567890abcdef0`	Provided by CSI driver
creationTime	Timestamp of snapshot creation	`2024-05-15T10:30:00Z`	ISO 8601 format
readyToUse	Indicates if snapshot is ready for use	`true` or `false`	Used in volume creation

Example: Create Volume from Snapshot

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: pvc-from-snapshot
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi
  dataSource:
    apiGroup: snapshot.storage.k8s.io
    kind: VolumeSnapshot
    name: example-snapshot

Note: The dataSource field must reference a valid VolumeSnapshot resource in the same namespace.

Warning: Ensure that the CSI driver supports volume cloning or snapshotting features before using them.

9. Deleting VolumeSnapshots

Field	Description	Values
apiVersion	API version of the VolumeSnapshot resource	`snapshot.storage.k8s.io/v1`
kind	Kind of the resource	`VolumeSnapshot`
metadata.name	Name of the VolumeSnapshot to delete	`snapshot-name`

Example: Delete VolumeSnapshot using kubectl

kubectl delete volumesnapshot &lt;snapshot-name&gt;

Note: Deleting a VolumeSnapshot will also delete the underlying snapshot in the storage provider.

Warning: Ensure that no pods are using the volume associated with this snapshot before deletion.

10. Troubleshooting Snapshot Issues

Issue	Potential Causes	Solution Steps
Snapshot creation fails	`StorageClass` does not support snapshots, insufficient permissions, or volume is in use.	Verify `StorageClass` supports snapshots. Check permissions for CSI driver and volume. Ensure volume is not mounted in any pod.
Snapshot status stuck as "Pending"	Storage backend is slow or unresponsive, missing CSI driver support.	Check logs from CSI driver and storage backend. Confirm snapshot is supported by the volume plugin.
Snapshot restore fails	Snapshot is corrupted, incompatible with source volume, or missing from storage backend.	Validate snapshot integrity using `kubectl describe volumesnapshot`. Ensure source and restore volume types match.

Example: Describe VolumeSnapshot for diagnostics

kubectl describe volumesnapshot &lt;snapshot-name&gt;

Note: Use kubectl get volumesnapshot to check the status and kubectl get volumesnapshotcontent for underlying storage details.

Warning: Do not delete a VolumeSnapshotContent if it is still referenced by a VolumeSnapshot, as this can lead to data loss.