## Prerequisite For clone, we need to have `VolumeSnapshotDataSource` support, which is in beta in Kubernetes 1.17. If you are using the Kubernetes version less than 1.17, you have to enable the `VolumeSnapshotDataSource` feature gate at kubelet and kube-apiserver. ## Create Clone From Snapshot We can create a clone volume from a snapshot and use that volume for some application. We can create a PVC YAML and mention the snapshot name in the datasource. ``` $ cat clone.yaml kind: PersistentVolumeClaim apiVersion: v1 metadata: name: zfspv-clone spec: storageClassName: openebs-zfspv dataSource: name: zfspv-snap kind: VolumeSnapshot apiGroup: snapshot.storage.k8s.io accessModes: - ReadWriteOnce resources: requests: storage: 4Gi ``` The above yaml says that create a volume from the snapshot zfspv-snap. Applying the above yaml will create a clone volume on the same node where the original volume is present. The newly created clone PV will also be there on the same node where the original PV is there. Apply the clone yaml ``` $ kubectl apply -f clone.yaml persistentvolumeclaim/zfspv-clone created ``` Note that the clone PVC should also be of the same size as that of the original volume. Currently resize is not supported. Also, note that the poolname should also be same, as across the ZPOOL clone is not supported. So, if you are using a separate storageclass for the clone PVC, please make sure it refers to the same ZPOOL. ``` $ kubectl get pvc NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE csi-zfspv Bound pvc-73402f6e-d054-4ec2-95a4-eb8452724afb 4Gi RWO openebs-zfspv 13m zfspv-clone Bound pvc-c095aa52-8d09-4bbe-ac3c-bb88a0e7be19 4Gi RWO openebs-zfspv 34s ``` We can see in the above output that zfspv-clone claim has been created and it is bound. Also, we can check the zfs list on node and verify that clone volume is created. ``` $ zfs list -t all NAME USED AVAIL REFER MOUNTPOINT test-pool 834K 9.63G 24K /test-pool test-pool/pvc-73402f6e-d054-4ec2-95a4-eb8452724afb 24K 4.00G 24K /var/lib/kubelet/pods/3862895a-8a67-446e-80f7-f3c18881e391/volumes/kubernetes.io~csi/pvc-73402f6e-d054-4ec2-95a4-eb8452724afb/mount test-pool/pvc-73402f6e-d054-4ec2-95a4-eb8452724afb@snapshot-3cbd5e59-4c6f-4bd6-95ba-7f72c9f12fcd 0B - 24K - test-pool/pvc-c095aa52-8d09-4bbe-ac3c-bb88a0e7be19 0B 9.63G 24K none ``` The clone volume will have properties same as snapshot properties which are the properties when that snapshot has been created. The ZFSVolume object for the clone volume will be something like below: ``` $ kubectl describe zv pvc-c095aa52-8d09-4bbe-ac3c-bb88a0e7be19 -n openebs Name: pvc-c095aa52-8d09-4bbe-ac3c-bb88a0e7be19 Namespace: openebs Labels: kubernetes.io/nodename=e2e1-node2 Annotations: none API Version: openebs.io/v1alpha1 Kind: ZFSVolume Metadata: Creation Timestamp: 2020-02-25T08:34:25Z Finalizers: zfs.openebs.io/finalizer Generation: 1 Resource Version: 448930 Self Link: /apis/openebs.io/v1alpha1/namespaces/openebs/zfsvolumes/pvc-c095aa52-8d09-4bbe-ac3c-bb88a0e7be19 UID: e38a9f9a-fb76-466b-a6f9-8d070e0bec6f Spec: Capacity: 4294967296 Fs Type: zfs Owner Node ID: e2e1-node2 Pool Name: test-pool Snapname: pvc-73402f6e-d054-4ec2-95a4-eb8452724afb@snapshot-3cbd5e59-4c6f-4bd6-95ba-7f72c9f12fcd Volume Type: DATASET Events: none ``` Here you can note that this resource has Snapname field which tells that this volume is created from that snapshot. ## Create Clone From Volume We can create a clone volume from an existing volume and use that volume for some application. We can create a PVC YAML and mention the source volume name from where we want to create the clone in the datasource. ``` $ cat clone.yaml kind: PersistentVolumeClaim apiVersion: v1 metadata: name: zfspv-clone spec: storageClassName: openebs-zfspv dataSource: name: zfspv-pvc kind: PersistentVolumeClaim accessModes: - ReadWriteOnce resources: requests: storage: 4Gi ``` The above yaml says that create a clone from the pvc zfspv-pvc as source. Applying the above yaml will create a clone volume on the same node where the original volume is present. The newly created clone PV will also be there on the same node where the original PV is there. Apply the clone yaml ``` $ kubectl apply -f clone.yaml persistentvolumeclaim/zfspv-clone created ``` Note that the clone PVC should also be of the same size as that of the original volume. Also, note that the poolname should also be same, as across the ZPOOL clone is not supported. So, if you are using a separate storageclass for the clone PVC, please make sure it refers to the same ZPOOL. ``` $ kubectl get pvc NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE zfspv-clone Bound pvc-b757fbca-f008-49c6-954e-7ea3e1c1bbc7 4Gi RWO openebs-zfspv 52s zfspv-pvc Bound pvc-9df1e7ba-bcb1-414a-b318-5084f4f6edeb 4Gi RWO openebs-zfspv 92s ``` We can see in the above output that zfspv-clone claim has been created and it is bound. Also, we can check the zfs list on node and verify that clone volume is created. ``` $ zfs list -t all NAME USED AVAIL REFER MOUNTPOINT zfspv-pool 4.26G 497G 24K /zfspv-pool zfspv-pool/pvc-9df1e7ba-bcb1-414a-b318-5084f4f6edeb 4.25G 502G 130M - zfspv-pool/pvc-9df1e7ba-bcb1-414a-b318-5084f4f6edeb@pvc-b757fbca-f008-49c6-954e-7ea3e1c1bbc7 0B - 130M - zfspv-pool/pvc-b757fbca-f008-49c6-954e-7ea3e1c1bbc7 67K 497G 130M - ``` The clone volume will have properties same as source volume properties at the time of creating the clone. The ZFSVolume object for the clone volume will be something like below: ``` $ kubectl describe zv pvc-b757fbca-f008-49c6-954e-7ea3e1c1bbc7 -n openebs Name: pvc-b757fbca-f008-49c6-954e-7ea3e1c1bbc7 Namespace: openebs Labels: kubernetes.io/nodename=pawan-node-1 openebs.io/source-volume=pvc-9df1e7ba-bcb1-414a-b318-5084f4f6edeb Annotations: API Version: zfs.openebs.io/v1 Kind: ZFSVolume Metadata: Creation Timestamp: 2020-12-10T05:00:54Z Finalizers: zfs.openebs.io/finalizer Generation: 2 Resource Version: 53615100 Self Link: /apis/zfs.openebs.io/v1/namespaces/openebs/zfsvolumes/pvc-b757fbca-f008-49c6-954e-7ea3e1c1bbc7 UID: b67ea231-0f5c-4d15-918c-425160706953 Spec: Capacity: 4294967296 Owner Node ID: pawan-node-1 Pool Name: zfspv-pool Snapname: pvc-9df1e7ba-bcb1-414a-b318-5084f4f6edeb@pvc-b757fbca-f008-49c6-954e-7ea3e1c1bbc7 Volume Type: ZVOL Status: State: Ready Events: ``` The ZFS-LocalPV driver creates an internal snapshot on the source volume with the name same as clone volume name and then creates the clone from that snapshot. Here you can note that this resource has Snapname field which tells that this volume is created from that internal snapshot.