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Snapshots

Prerequisites

  • Rook officially supports v1 snapshots for Kubernetes v1.20+.

  • Install the snapshot controller and snapshot v1 CRD as required. More info can be found here.

Note

If only Alpha snapshots are available, enable snapshotter in rook-ceph-operator-config or helm chart values.yaml, change the external-snapshotter image to registry.k8s.io/sig-storage/csi-snapshotter:v1.2.2 and refer to the alpha snapshots documentation

VolumeSnapshot betav1 is deprecated in Kubernetes 1.20+ and removed in 1.24.0. If you still require betav1 snapshots, change the external-snapshotter image to registry.k8s.io/sig-storage/csi-snapshotter:v5.0.1 and refer to the betav1 snapshots documentation

  • We also need a VolumeSnapshotClass for volume snapshot to work. The purpose of a VolumeSnapshotClass is defined in the kubernetes documentation. In short, as the documentation describes it:

Info

Just like StorageClass provides a way for administrators to describe the "classes" of storage they offer when provisioning a volume, VolumeSnapshotClass provides a way to describe the "classes" of storage when provisioning a volume snapshot.

Upgrade Snapshot API

If your Kubernetes version is updated to a newer version of the snapshot API, follow the upgrade guide here to upgrade from v1alpha1 to v1beta1, or v1beta1 to v1.

RBD Snapshots

VolumeSnapshotClass

In VolumeSnapshotClass, the csi.storage.k8s.io/snapshotter-secret-name parameter should reference the name of the secret created for the rbdplugin and pool to reflect the Ceph pool name.

Update the value of the clusterID field to match the namespace that Koor Storage Distribution is running in. When Ceph CSI is deployed by Rook, the operator will automatically maintain a configmap whose contents will match this key. By default this is "rook-ceph".

kubectl create -f deploy/examples/csi/rbd/snapshotclass.yaml

Volumesnapshot

In snapshot, volumeSnapshotClassName should be the name of the VolumeSnapshotClass previously created. The persistentVolumeClaimName should be the name of the PVC which is already created by the RBD CSI driver.

kubectl create -f deploy/examples/csi/rbd/snapshot.yaml

Verify RBD Snapshot Creation

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$ kubectl get volumesnapshotclass
NAME                      DRIVER                       DELETIONPOLICY   AGE
csi-rbdplugin-snapclass   rook-ceph.rbd.csi.ceph.com   Delete           3h55m
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$ kubectl get volumesnapshot
NAME               READYTOUSE   SOURCEPVC   SOURCESNAPSHOTCONTENT   RESTORESIZE   SNAPSHOTCLASS             SNAPSHOTCONTENT                                    CREATIONTIME   AGE
rbd-pvc-snapshot   true         rbd-pvc                             1Gi           csi-rbdplugin-snapclass   snapcontent-79090db0-7c66-4b18-bf4a-634772c7cac7   3h50m          3h51m

The snapshot will be ready to restore to a new PVC when the READYTOUSE field of the volumesnapshot is set to true.

Restore the snapshot to a new PVC

In pvc-restore, dataSource should be the name of the VolumeSnapshot previously created. The dataSource kind should be the VolumeSnapshot.

Create a new PVC from the snapshot

kubectl create -f deploy/examples/csi/rbd/pvc-restore.yaml

Verify RBD Clone PVC Creation

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$ kubectl get pvc
NAME              STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS          AGE
rbd-pvc           Bound    pvc-84294e34-577a-11e9-b34f-525400581048   1Gi        RWO            rook-ceph-block       34m
rbd-pvc-restore   Bound    pvc-575537bf-577f-11e9-b34f-525400581048   1Gi        RWO            rook-ceph-block       8s

RBD snapshot resource Cleanup

To clean your cluster of the resources created by this example, run the following:

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kubectl delete -f deploy/examples/csi/rbd/pvc-restore.yaml
kubectl delete -f deploy/examples/csi/rbd/snapshot.yaml
kubectl delete -f deploy/examples/csi/rbd/snapshotclass.yaml

CephFS Snapshots

VolumeSnapshotClass

In VolumeSnapshotClass, the csi.storage.k8s.io/snapshotter-secret-name parameter should reference the name of the secret created for the cephfsplugin.

In the volumesnapshotclass, update the value of the clusterID field to match the namespace that Koor Storage Distribution is running in. When Ceph CSI is deployed by Rook, the operator will automatically maintain a configmap whose contents will match this key. By default this is "rook-ceph".

kubectl create -f deploy/examples/csi/cephfs/snapshotclass.yaml

VolumeSnapshot

In snapshot, volumeSnapshotClassName should be the name of the VolumeSnapshotClass previously created. The persistentVolumeClaimName should be the name of the PVC which is already created by the CephFS CSI driver.

kubectl create -f deploy/examples/csi/cephfs/snapshot.yaml

Verify CephFS Snapshot Creation

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$ kubectl get volumesnapshotclass
NAME                        DRIVER                          DELETIONPOLICY   AGE
csi-cephfslugin-snapclass   rook-ceph.cephfs.csi.ceph.com   Delete           3h55m
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$ kubectl get volumesnapshot
NAME                  READYTOUSE   SOURCEPVC   SOURCESNAPSHOTCONTENT  RESTORESIZE   SNAPSHOTCLASS                SNAPSHOTCONTENT                                   CREATIONTIME   AGE
cephfs-pvc-snapshot   true         cephfs-pvc                         1Gi           csi-cephfsplugin-snapclass   snapcontent-34476204-a14a-4d59-bfbc-2bbba695652c  3h50m          3h51m

The snapshot will be ready to restore to a new PVC when READYTOUSE field of the volumesnapshot is set to true.

Restore the snapshot to a new PVC

In pvc-restore, dataSource should be the name of the VolumeSnapshot previously created. The dataSource kind should be the VolumeSnapshot.

Create a new PVC from the snapshot

kubectl create -f deploy/examples/csi/cephfs/pvc-restore.yaml

Verify CephFS Restore PVC Creation

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$ kubectl get pvc
NAME                 STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS      AGE
cephfs-pvc           Bound    pvc-74734901-577a-11e9-b34f-525400581048   1Gi        RWX            rook-cephfs       55m
cephfs-pvc-restore   Bound    pvc-95308c75-6c93-4928-a551-6b5137192209   1Gi        RWX            rook-cephfs       34s

CephFS snapshot resource Cleanup

To clean your cluster of the resources created by this example, run the following:

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kubectl delete -f deploy/examples/csi/cephfs/pvc-restore.yaml
kubectl delete -f deploy/examples/csi/cephfs/snapshot.yaml
kubectl delete -f deploy/examples/csi/cephfs/snapshotclass.yaml

Limitations

  • There is a limit of 400 snapshots per cephFS filesystem.
  • The PVC cannot be deleted if it has snapshots. make sure all the snapshots on the PVC are deleted before you delete the PVC.
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