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title: Volume Group Snapshots
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---
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Ceph provides the ability to create crash-consistent snapshots of multiple volumes.
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A group snapshot represents “copies” from multiple volumes that are taken at the same point in time.
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A group snapshot can be used either to rehydrate new volumes (pre-populated with the snapshot data)
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or to restore existing volumes to a previous state (represented by the snapshots)
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## Prerequisites
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- Install the [snapshot controller, volume group snapshot and snapshot CRDs](https://github.com/kubernetes-csi/external-snapshotter/tree/master#usage),
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refer to VolumeGroupSnapshot documentation
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[here](https://github.com/kubernetes-csi/external-snapshotter/tree/master#volume-group-snapshot-support) for more details.
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- A `VolumeGroupSnapshotClass` is needed for the volume group snapshot to work. The purpose of a `VolumeGroupSnapshotClass` is
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defined in [the kubernetes
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documentation](https://kubernetes.io/blog/2023/05/08/kubernetes-1-27-volume-group-snapshot-alpha/).
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In short, as the documentation describes it:
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!!! info
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Created by cluster administrators to describe how volume group snapshots
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should be created. including the driver information, the deletion policy, etc.
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## Volume Group Snapshots
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### CephFS VolumeGroupSnapshotClass
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In [VolumeGroupSnapshotClass](https://github.com/rook/rook/tree/master/deploy/examples/csi/cephfs/groupsnapshotclass.yaml),
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the `csi.storage.k8s.io/group-snapshotter-secret-name` parameter should reference the
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name of the secret created for the cephfs-plugin.
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In the `VolumeGroupSnapshotClass`, update the value of the `clusterID` field to match the namespace
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that Rook is running in. When Ceph CSI is deployed by Rook, the operator will automatically
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maintain a configmap whose contents will match this key. By default this is
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"rook-ceph".
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```console
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kubectl create -f deploy/examples/csi/cephfs/groupsnapshotclass.yaml
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```
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### CephFS VolumeGroupSnapshot
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In [VolumeGroupSnapshot](https://github.com/rook/rook/tree/master/deploy/examples/csi/cephfs/groupsnapshot.yaml),
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`volumeGroupSnapshotClassName` should be the name of the `VolumeGroupSnapshotClass`
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previously created. The labels inside `matchLabels` should be present on the
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PVCs that are already created by the CephFS CSI driver.
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```console
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kubectl create -f deploy/examples/csi/cephfs/groupsnapshot.yaml
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```
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### Verify CephFS GroupSnapshot Creation
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```console
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$ kubectl get volumegroupsnapshotclass
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NAME DRIVER DELETIONPOLICY AGE
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csi-cephfsplugin-groupsnapclass rook-ceph.cephfs.csi.ceph.com Delete 21m
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```
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```console
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$ kubectl get volumegroupsnapshot
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NAME READYTOUSE VOLUMEGROUPSNAPSHOTCLASS VOLUMEGROUPSNAPSHOTCONTENT CREATIONTIME AGE
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cephfs-groupsnapshot true csi-cephfsplugin-groupsnapclass groupsnapcontent-d13f4d95-8822-4729-9586-4f222a3f788e 5m37s 5m39s
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```
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The snapshot will be ready to restore to a new PVC when `READYTOUSE` field of the
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`volumegroupsnapshot` is set to true.
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### Restore the CephFS volume group snapshot to a new PVC
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Find the name of the snapshots created by the `VolumeGroupSnapshot` first by running:
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```console
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$ kubectl get volumegroupsnapshot/cephfs-groupsnapshot -o=jsonpath='{range .status.pvcVolumeSnapshotRefList[*]}PVC: {.persistentVolumeClaimRef.name}, Snapshot: {.volumeSnapshotRef.name}{"\n"}{end}'
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PVC: cephfs-pvc, Snapshot: snapshot-9d21b143904c10f49ddc92664a7e8fe93c23387d0a88549c14337484ebaf1011-2024-09-12-3.49.13
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```
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It will list the PVC's name followed by its snapshot name.
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In
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[pvc-restore](https://github.com/rook/rook/tree/master/deploy/examples/csi/cephfs/pvc-restore.yaml),
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`dataSource` should be one of the `Snapshot` that we just
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found. The `dataSource` kind should be the `VolumeSnapshot`.
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Create a new PVC from the snapshot
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```console
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kubectl create -f deploy/examples/csi/cephfs/pvc-restore.yaml
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```
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### Verify CephFS Restore PVC Creation
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```console
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$ kubectl get pvc
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cephfs-pvc Bound pvc-9ae60bf9-4931-4f9a-9de1-7f45f31fe4da 1Gi RWO rook-cephfs <unset> 171m
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cephfs-pvc-restore Bound pvc-b4b73cbb-5061-48c7-9ac8-e1202508cf97 1Gi RWO rook-cephfs <unset> 46s
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```
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## CephFS volume group snapshot resource Cleanup
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To clean the resources created by this example, run the following:
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```console
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kubectl delete -f deploy/examples/csi/cephfs/pvc-restore.yaml
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kubectl delete -f deploy/examples/csi/cephfs/groupsnapshot.yaml
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kubectl delete -f deploy/examples/csi/cephfs/groupsnapshotclass.yaml
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```
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