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chore(doc): updating readme with snapshot and clone details
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Signed-off-by: Pawan <pawan@mayadata.io>
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@pawanpraka1 @kmova
pawanpraka1 authored and kmova committed Feb 29, 2020
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Expand Up @@ -328,7 +328,185 @@ below command on the node:
zfs get all zfspv-pool/pvc-34133838-0d0d-11ea-96e3-42010a800114
```

#### 7. Deprovisioning
#### 7. Snapshot

We can create a snapshot of a volume which can be used further for creating a clone and for taking a backup. To create a snapshot, we have to first create a snapshotclass just like a storage class.

```yaml
kind: VolumeSnapshotClass
apiVersion: snapshot.storage.k8s.io/v1beta1
metadata:
name: zfspv-snapclass
annotations:
snapshot.storage.kubernetes.io/is-default-class: "true"
driver: zfs.csi.openebs.io
deletionPolicy: Delete
```

Then create the snapshot using the above snapshotclass :

```yaml
apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshot
metadata:
name: zfspv-snap
spec:
volumeSnapshotClassName: zfspv-snapclass
source:
persistentVolumeClaimName: csi-zfspv
```
Plese note that, you have to create the snapshot in the same namespace where the pvc is created. Check the created snapshot resource, make sure readyToUse field is true, before using this snapshot for any purpose.

```
$ kubectl get volumesnapshot.snapshot
NAME AGE
zfspv-snap 2m8s
$ kubectl get volumesnapshot.snapshot zfspv-snap -o yaml
apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshot
metadata:
annotations:
kubectl.kubernetes.io/last-applied-configuration: |
{"apiVersion":"snapshot.storage.k8s.io/v1beta1","kind":"VolumeSnapshot","metadata":{"annotations":{},"name":"zfspv-snap","namespace":"default"},"spec":{"source":{"persistentVolumeClaimName":"csi-zfspv"},"volumeSnapshotClassName":"zfspv-snapclass"}}
creationTimestamp: "2020-02-25T08:25:51Z"
finalizers:
- snapshot.storage.kubernetes.io/volumesnapshot-as-source-protection
- snapshot.storage.kubernetes.io/volumesnapshot-bound-protection
generation: 1
name: zfspv-snap
namespace: default
resourceVersion: "447494"
selfLink: /apis/snapshot.storage.k8s.io/v1beta1/namespaces/default/volumesnapshots/zfspv-snap
uid: 3cbd5e59-4c6f-4bd6-95ba-7f72c9f12fcd
spec:
source:
persistentVolumeClaimName: csi-zfspv
volumeSnapshotClassName: zfspv-snapclass
status:
boundVolumeSnapshotContentName: snapcontent-3cbd5e59-4c6f-4bd6-95ba-7f72c9f12fcd
creationTime: "2020-02-25T08:25:51Z"
readyToUse: true
restoreSize: "0"
```

Check the OpenEBS resource for the created snapshot. Check, status should be Ready.

```
$ kubectl get zfssnap -n openebs
NAME AGE
snapshot-3cbd5e59-4c6f-4bd6-95ba-7f72c9f12fcd 3m32s
$ kubectl get zfssnap snapshot-3cbd5e59-4c6f-4bd6-95ba-7f72c9f12fcd -n openebs -oyaml
apiVersion: openebs.io/v1alpha1
kind: ZFSSnapshot
metadata:
creationTimestamp: "2020-02-25T08:25:51Z"
finalizers:
- zfs.openebs.io/finalizer
generation: 2
labels:
kubernetes.io/nodename: zfspv-node1
openebs.io/persistent-volume: pvc-34133838-0d0d-11ea-96e3-42010a800114
name: snapshot-3cbd5e59-4c6f-4bd6-95ba-7f72c9f12fcd
namespace: openebs
resourceVersion: "447328"
selfLink: /apis/openebs.io/v1alpha1/namespaces/openebs/zfssnapshots/snapshot-3cbd5e59-4c6f-4bd6-95ba-7f72c9f12fcd
uid: 6142492c-3785-498f-aa4a-569ec6c0e2b8
spec:
capacity: "4294967296"
fsType: zfs
ownerNodeID: zfspv-node1
poolName: zfspv-pool
volumeType: DATASET
status:
state: Ready
```

we can go to the node and confirm that snapshot has been created :-

```
$ zfs list -t all
NAME USED AVAIL REFER MOUNTPOINT
zfspv-pool 468K 96.4G 96K /zfspv-pool
zfspv-pool/pvc-34133838-0d0d-11ea-96e3-42010a800114 96K 4.00G 96K none
zfspv-pool/pvc-34133838-0d0d-11ea-96e3-42010a800114@snapshot-3cbd5e59-4c6f-4bd6-95ba-7f72c9f12fcd 0B - 96K -
```

#### 8. Clone

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. Please note that for kubernetes version less than 1.17, `VolumeSnapshotDataSource` feature gate needs to be enabled at kubelet and kube-apiserver

```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.

Note that the clone PVC should also be of the same size as that of the original volume as right now 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-34133838-0d0d-11ea-96e3-42010a800114 4Gi RWO openebs-zfspv 3h42m
zfspv-clone Bound pvc-e1230d2c-b32a-48f7-8b76-ca335b253dcd 4Gi RWO openebs-zfspv 78s
```

We can see in the above output that zfspv-clone claim has been created and it is bound also. 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 444K 96.4G 96K /zfspv-pool
zfspv-pool/pvc-e1230d2c-b32a-48f7-8b76-ca335b253dcd 0B 4G 96K none
zfspv-pool/pvc-34133838-0d0d-11ea-96e3-42010a800114 96K 4.00G 96K none
zfspv-pool/pvc-34133838-0d0d-11ea-96e3-42010a800114@snapshot-3cbd5e59-4c6f-4bd6-95ba-7f72c9f12fcd 0B - 96K -
```

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-e1230d2c-b32a-48f7-8b76-ca335b253dcd -n openebs
Name: pvc-e1230d2c-b32a-48f7-8b76-ca335b253dcd
Namespace: openebs
Labels: kubernetes.io/nodename=zfspv-node1
Annotations: <none>
API Version: openebs.io/v1alpha1
Kind: ZFSVolume
Metadata:
Creation Timestamp: 2019-11-22T09:49:29Z
Finalizers:
zfs.openebs.io/finalizer
Generation: 1
Resource Version: 2881
Self Link: /apis/openebs.io/v1alpha1/namespaces/openebs/zfsvolumes/pvc-e1230d2c-b32a-48f7-8b76-ca335b253dcd
UID: 60bc4df2-0d0d-11ea-96e3-42010a800114
Spec:
Capacity: 4294967296
Fs Type: zfs
Owner Node ID: zfspv-node1
Pool Name: zfspv-pool
Snap Name: pvc-34133838-0d0d-11ea-96e3-42010a800114@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.
```
#### 9. Deprovisioning
for deprovisioning the volume we can delete the application which is using the volume and then we can go ahead and delete the pv, as part of deletion of pv this volume will also be deleted from the ZFS pool and data will be freed.

```
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