Chapter 12. Volume Snapshots

A volume snapshot is the state of the storage volume in a cluster at a particular point in time. These snapshots help to use storage more efficiently by not having to make a full copy each time and can be used as building blocks for developing an application.

You can create multiple snapshots of the same persistent volume claim (PVC). For CephFS, you can create up to 100 snapshots per PVC. For RADOS Block Device (RBD), you can create up to 512 snapshots per PVC.

Note

You cannot schedule periodic creation of snapshots.

12.1. Creating volume snapshots

You can create a volume snapshot either from the Persistent Volume Claim (PVC) page or the Volume Snapshots page.

Prerequisites

  • For a consistent snapshot, the PVC should not be in use or Bound state. Ensure to stop all IO before taking the snapshot.
Note

OpenShift Container Storage only provides crash consistency for a volume snapshot of a PVC if a pod is using it. For application consistency, be sure to first tear down a running pod to ensure consistent snapshots or use any quiesce mechanism provided by the application to ensure it.

Procedure

From the Persistent Volume Claims page
  1. Click StoragePersistent Volume Claims from the OpenShift Web Console.
  2. To create a volume snapshot, do one of the following:

    • Beside the desired PVC, click Action menu (⋮)Create Snapshot.
    • Click on the PVC for which you want to create the snapshot and click ActionsCreate Snapshot.
  3. Enter a Name for the volume snapshot.
  4. Choose the Snapshot Class from the drop-down list.
  5. Click Create. You will be redirected to the Details page of the volume snapshot that is created.
From the Volume Snapshots page
  1. Click StorageVolume Snapshots from the OpenShift Web Console.
  2. In the Volume Snapshots page, click Create Volume Snapshot.
  3. Choose the required Project from the drop-down list.
  4. Choose the Persistent Volume Claim from the drop-down list.
  5. Enter a Name for the snapshot.
  6. Choose the Snapshot Class from the drop-down list.
  7. Click Create. You will be redirected to the Details page of the volume snapshot that is created.

Verification steps

  • Go to the Details page of the PVC and click the Volume Snapshots tab to see the list of volume snapshots. Verify that the new volume snapshot is listed.
  • Click StorageVolume Snapshots from the OpenShift Web Console. Verify that the new volume snapshot is listed.
  • Wait for the volume snapshot to be in Ready state.

12.2. Restoring volume snapshots

When you restore a volume snapshot, a new Persistent Volume Claim (PVC) gets created. The restored PVC is independent of the volume snapshot and the parent PVC.

You can restore a volume snapshot from either the Persistent Volume Claim page or the Volume Snapshots page.

Procedure

From the Persistent Volume Claims page

You can restore volume snapshot from the Persistent Volume Claims page only if the parent PVC is present.

  1. Click StoragePersistent Volume Claims from the OpenShift Web Console.
  2. Click on the PVC name with the volume snapshot to restore a volume snapshot as a new PVC.
  3. In the Volume Snapshots tab, click the Action menu (⋮) next to the volume snapshot you want to restore.
  4. Click Restore as new PVC.
  5. Enter a name for the new PVC.
  6. Select the Access Mode of your choice.

    Important

    The ReadOnlyMany (ROX) access mode is a Developer Preview feature and is subject to Developer Preview support limitations. Developer Preview releases are not intended to be run in production environments and are not supported through the Red Hat Customer Portal case management system. If you need assistance with ReadOnlyMany feature, reach out to the ocs-devpreview@redhat.com mailing list and a member of the Red Hat Development Team will assist you as quickly as possible based on availability and work schedules. See Creating a clone or restoring a snapshot with the new readonly access mode to use the ROX access mode.

  7. Select the Storage Class name.

    Note

    For Rados Block Device (RBD), you must select a storage class with the same pool as that of the parent PVC.

  8. Click Restore. You are redirected to the new PVC details page.
From the Volume Snapshots page
  1. Click StorageVolume Snapshots from the OpenShift Web Console.
  2. In the Volume Snapshots tab, click the Action menu (⋮) next to the volume snapshot you want to restore.
  3. Click Restore as new PVC.
  4. Enter a name for the new PVC.
  5. Select the Access Mode of your choice.

    Important

    The ReadOnlyMany (ROX) access mode is a Developer Preview feature and is subject to Developer Preview support limitations. Developer Preview releases are not intended to be run in production environments and are not supported through the Red Hat Customer Portal case management system. If you need assistance with ReadOnlyMany feature, reach out to the ocs-devpreview@redhat.com mailing list and a member of the Red Hat Development Team will assist you as quickly as possible based on availability and work schedules. See Creating a clone or restoring a snapshot with the new readonly access mode to use the ROX access mode.

  6. Select the Storage Class name.

    Note

    For Rados Block Device (RBD), you must select a storage class with the same pool as that of the parent PVC.

  7. Click Restore. You are redirected to the new PVC details page.

Verification steps

  • Click StoragePersistent Volume Claims from the OpenShift Web Console and confirm that the new PVC is listed in the Persistent Volume Claims page.
  • Wait for the new PVC to reach Bound state.

12.3. Deleting volume snapshots

Prerequisites

  • For deleting a volume snapshot, the volume snapshot class which is used in that particular volume snapshot should be present.

Procedure

From Persistent Volume Claims page
  1. Click StoragePersistent Volume Claims from the OpenShift Web Console.
  2. Click on the PVC name which has the volume snapshot that needs to be deleted.
  3. In the Volume Snapshots tab, beside the desired volume snapshot, click Action menu (⋮)Delete Volume Snapshot.
From Volume Snapshots page
  1. Click StorageVolume Snapshots from the OpenShift Web Console.
  2. In the Volume Snapshots page, beside the desired volume snapshot click Action menu (⋮)Delete Volume Snapshot.

Verfication steps

  • Ensure that the deleted volume snapshot is not present in the Volume Snapshots tab of the PVC details page.
  • Click StorageVolume Snapshots and ensure that the deleted volume snapshot is not listed.