HPE SimpliVity CSI Driver - Volume Snapshots

For dynamic volume creation, creating a PersistentVolumeClaim (PVC) initiates the creation of a PersistentVolume (PV) which contains the data. A PVC also specifies a StorageClass which provides additional attributes (e.g. SimpliVity datastore).

The CSI snapshot feature follows the same pattern. Creating a VolumeSnapshot triggers creation of a VolumeSnapshotContent object which contains the snapshot data. A VolumeSnapshot also specifies a VolumeSnapshotClass to provide additional attributes (e.g. retention policy).

VolumeSnapshotContent: The Kubernetes cluster resource that represents a snapshot of a persistent volume.
VolumeSnapshot: A snapshot request. Creating a VolumeSnapshot triggers a snapshot (VolumeSnapshotContent) and the objects are bound together. There is a one-to-one mapping between VolumeSnapshot and VolumeSnapshotContent objects.
VolumeSnapshotClass: Dynamically provisioned snapshots specify a VolumeSnapshotClass to provide additional parameters for the snapshot operation. This is similar to how a StorageClass is used for PVs, and allows volumes created from the same StorageClass to be snapshotted with different options (e.g. retention policy).

Volume Snapshot Provisioning

There are two types of snapshot provisioning in a Kubernetes cluster:

Dynamic Volume Snapshot: Create an on-demand snapshot.
Static Volume Snapshot: Create a snapshot for a pre-existing HPE SimpliVity snapshot. For example, to create a Kubernetes snapshot from a scheduled backup.

Dynamic Volume Snapshot

Volume snapshots of HPE SimpliVity volumes can be created on demand using the Kubernetes CLI. To do so, create a VolumeSnapshot object containing the PersistentVolumeClaim that you wish to snap. Kubernetes does not quiesce IO during a snapshot operation and thus the snapshot will just be crash consistent. To take an application consistent snapshot, you must take additional steps (e.g. shutdown the pod consuming the PV).

Dynamic Snapshot Procedure

Define a VolumeSnapshotClass. The deletionPolicy enables you to configure what happens to a VolumeSnapshotContent object when the VolumeSnapshot object to which it is bound is deleted. The deletionPolicy of a volume snapshot can either be Retain or Delete.

apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshotClass
metadata:
  name: hpe-simplivity-snapclass
driver: csi.simplivity.hpe.com
deletionPolicy: Delete
parameters:
  description: "Snapshot created by the HPE SimpliVity vSphere CSI Driver"

Create the VolumeSnapshotClass object.

$ kubectl create -f example-snapshotclass.yaml

Define a VolumeSnapshot object. volumeSnapshotClassName specifies the snapshot options (defined in step 2) and persistentVolumeClaim identifies the snapshot source volume.

apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshot
metadata:
  name: www-web-snap-1
spec:
  volumeSnapshotClassName: hpe-simplivity-snapclass
  source:
    persistentVolumeClaimName: www-web-0

Create the VolumeSnapshot object to request a snapshot.
```
$ kubectl create -f dynamic-snapshot.yaml
```

Verify the VolumeSnapshot object was created in Kubernetes.

$ kubectl describe volumesnapshot www-web-snap-1
Name:         www-web-snap-1
Namespace:    default
Labels:       <none>
Annotations:  <none>
API Version:  snapshot.storage.k8s.io/v1beta1
Kind:         VolumeSnapshot
Metadata:
  Creation Timestamp:  2020-06-12T19:00:42Z
  Finalizers:
    snapshot.storage.kubernetes.io/volumesnapshot-as-source-protection
    snapshot.storage.kubernetes.io/volumesnapshot-bound-protection
  Generation:        1
  Resource Version:  8840186
  Self Link:         /apis/snapshot.storage.k8s.io/v1beta1/namespaces/default/volumesnapshots/www-web-snap-1
  UID:               7fa13b4b-f370-40c4-9946-4c7e2c72dcdc
Spec:
  Source:
    Persistent Volume Claim Name:  www-web-0
  Volume Snapshot Class Name:      hpe-simplivity-snapclass
Status:
  Bound Volume Snapshot Content Name:  snapcontent-7fa13b4b-f370-40c4-9946-4c7e2c72dcdc
  Creation Time:                       2020-06-12T19:01:08Z
  Ready To Use:                        true
  Restore Size:                        1Gi
Events:                                <none>

You can also verify the backup from HPE SimpliVity.

$ svt-backup-show --pv pvc-e3fe7f3b-e00a-4b0d-9d65-89c3564081be_fcd --datastore svt-ds
.----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------.
| Backups for PV 'pvc-e3fe7f3b-e00a-4b0d-9d65-89c3564081be_fcd' on datastore 'svt-ds'                                                                                                        |
+-----------------------------------------------+--------+-------------+----------------------+------------+------------+----------------+-----------+----------+------+-------------+---------+
| Backup                                        | Backup | Consistency | Backup               | Expiration | Datacenter | Cluster Or     | Status    | Size     | Sent | Replication | Family  |
| Name                                          | Type   | Type        | Time                 | Time       |            | External Store |           |          |      | End Time    |         |
+-----------------------------------------------+--------+-------------+----------------------+------------+------------+----------------+-----------+----------+------+-------------+---------+
| snapshot-7fa13b4b-f370-40c4-9946-4c7e2c72dcdc | Manual | None        | 2020-Jun-12 19:01:08 | N/A        | K8DC1      | K8Cluster1     | Protected | 656.00KB |   0B | N/A         | vSphere |
'-----------------------------------------------+--------+-------------+----------------------+------------+------------+----------------+-----------+----------+------+-------------+---------'

Static Volume Snapshot

Static volume snapshot provisioning allows cluster administrators to make existing snapshots available to a cluster. A common HPE SimpliVity use case is creating a snapshot from a scheduled backup.

Static Snapshot Procedure

Use the HPE SimpliVity svt-backup-show CLI to retrieve the ID of the backup that you wish to restore.

$ svt-backup-show --pv pvc-e3fe7f3b-e00a-4b0d-9d65-89c3564081be_fcd --datastore svt-ds --backup 2020-06-15T11:10:00-04:00 --output xml
<CommandResult>
    <Backup>
        <dsRemoved></dsRemoved>
        <datacenter>K8DC1</datacenter>
        <expirationTime>1592320200</expirationTime>
        <replicationStartTime>0</replicationStartTime>
        <datacenterName>K8DC1</datacenterName>
        <partial></partial>
        <associatedCluster>00000000-0000-0000-0000-000000000000</associatedCluster>
        <zoneStatus>1</zoneStatus>
        <computeClusterName>K8Cluster1</computeClusterName>
        <consistent></consistent>
        <lastTimeSizeCalc>0</lastTimeSizeCalc>
        <treeId>e8f03589-bdf3-4cc4-b401-e00c05c8ad11</treeId>
        <percentComp>0</percentComp>
        <uniqueSize>0</uniqueSize>
        <percentTrans>0</percentTrans>
        <dcId>e871a438-bcfc-476b-9081-7042a466771c</dcId>
        <sentSize>0</sentSize>
        <timestamp>1592233800</timestamp>
        <repTaskId>00000000-0000-0000-0000-000000000000</repTaskId>
        <computeClusterHmsId>9168aa17-f5a7-4d3c-94f6-5f7293bb80c3:ClusterComputeResource:domain-c7</computeClusterHmsId>
        <datacenterHmsId>9168aa17-f5a7-4d3c-94f6-5f7293bb80c3:Datacenter:datacenter-2</datacenterHmsId>
        <dsId>833a131c-09f2-46a3-94a9-e4b4342a9efe</dsId>
        <datastore>svt-ds</datastore>
        <hypervisorType>1</hypervisorType>
        <replicationElapsedSeconds>0</replicationElapsedSeconds>
        <externalStoreName></externalStoreName>
        <pedigree>1</pedigree>
        <omnistackClusterId>e871a438-bcfc-476b-9081-7042a466771c</omnistackClusterId>
        <logicalSize>671744</logicalSize>
        <consistency>0</consistency>
        <replicationAttempts>0</replicationAttempts>
        <hiveId>559273a8-f909-477d-8ca9-c6707b9208c3</hiveId>
        <name>2020-06-15T11:10:00-04:00</name>
        <replicationEndTime>0</replicationEndTime>
        <id>3edb760f-d9ad-4975-b8e4-0e1bc0394644</id>
        <hiveName>pvc-e3fe7f3b-e00a-4b0d-9d65-89c3564081be_fcd</hiveName>
        <backupId>3edb760f-d9ad-4975-b8e4-0e1bc0394644</backupId>
        <consistencyType>2</consistencyType>
        <replicaSet>c59a1042-3e83-d0c9-c28a-71bf95b68d64</replicaSet>
        <state>4</state>
        <hiveVolumeId>559273a8-f909-477d-8ca9-c6707b9208c3</hiveVolumeId>
        <backupStoreType>0</backupStoreType>
    </Backup>
</CommandResult>

Define a VolumeSnapshotContent object representing the pre-existing snapshot. The VolumeSnapshotContent name is a unique name of your choosing to represent the object in Kubernetes. The deletionPolicy enables you to configure what happens to a VolumeSnapshotContent object when the VolumeSnapshot object to which it is bound is deleted. The deletionPolicy of a volume snapshot can either be Retain or Delete. The snapshotHandle is the backup ID you retrieved in step 1. The volume snapshot reference name should be set to a unique name that you will set on the VolumeSnapshot object that will be bound to this VolumeSnapshotContent.
```
apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshotContent
metadata:
  name: static-snap-content
spec:
  deletionPolicy: Delete
  driver: csi.simplivity.hpe.com
  source:
    snapshotHandle: 3edb760f-d9ad-4975-b8e4-0e1bc0394644
  volumeSnapshotRef:
    name: static-snap-example
    namespace: default
```

Create the VolumeSnapshotContent object.

$ kubectl create -f static-snapshot-content.yaml

Define a VolumeSnapshot object. The name should match the volume snapshot reference name from the VolumeSnapshotContent object created in step 3. volumeSnapshotContentName specifies the name of the VolumeSnapshotContent object created in step 3.
```
kind: VolumeSnapshot
metadata:
  name: static-snap-example
spec:
  source:
    volumeSnapshotContentName: static-snap-content
```
Create the VolumeSnapshot object to bind the snapshot.
```
$ kubectl create -f static-snapshot.yaml
```

Verify the VolumeSnapshot object was created in Kubernetes.

$ kubectl describe volumesnapshot static-snap-example
Name:         static-snap-example
Namespace:    default
Labels:       <none>
Annotations:  <none>
API Version:  snapshot.storage.k8s.io/v1beta1
Kind:         VolumeSnapshot
Metadata:
  Creation Timestamp:  2020-06-15T16:07:22Z
  Finalizers:
    snapshot.storage.kubernetes.io/volumesnapshot-as-source-protection
    snapshot.storage.kubernetes.io/volumesnapshot-bound-protection
  Generation:        1
  Resource Version:  9789090
  Self Link:         /apis/snapshot.storage.k8s.io/v1beta1/namespaces/default/volumesnapshots/static-snap-example
  UID:               f90e5b74-cf68-40f2-bb28-95e85944d56b
Spec:
  Source:
    Volume Snapshot Content Name:  static-snap-content
Status:
  Bound Volume Snapshot Content Name:  static-snap-content
  Creation Time:                       2020-06-15T15:10:00Z
  Ready To Use:                        true
  Restore Size:                        0
Events:                                <none>

Restoring a Volume Snapshot

Once the VolumeSnapshot object is bound and ready to use, you can restore the volume using the VolumeSnapshotContent object. To do so, create a persistent volume claim which specifies the volume snapshot object as the volume source.

Snapshot Restore Procedure

Define a PersistentVolumeClaim. The dataSource allows you to specify the snapshot being restored.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: www-web-restore-1
spec:
  storageClassName: svt-sc
  dataSource:
    name: www-web-snap-1
    kind: VolumeSnapshot
    apiGroup: snapshot.storage.k8s.io
  accessModes:
    - ReadWriteOnce
  volumeMode: Filesystem
  resources:
    requests:
      storage: 1Gi

Create the PVC object.

$ kubectl create -f snap-restore.yaml
persistentvolumeclaim/www-web-restore-1 created

Verify the PVC was created successfully.

$ kubectl describe pvc www-web-restore-1
Name:          www-web-restore-1
Namespace:     default
StorageClass:  svt-sc
Status:        Bound
Volume:        pvc-72fb5f0e-5a93-44fd-a5fe-c82339093115
Labels:        <none>
Annotations:   pv.kubernetes.io/bind-completed: yes
              pv.kubernetes.io/bound-by-controller: yes
              volume.beta.kubernetes.io/storage-provisioner: csi.simplivity.hpe.com
Finalizers:    [kubernetes.io/pvc-protection]
Capacity:      1Gi
Access Modes:  RWO
VolumeMode:    Filesystem
DataSource:
  APIGroup:  snapshot.storage.k8s.io
  Kind:      VolumeSnapshot
  Name:      www-web-snap-1
Mounted By:  <none>
Events:
  Type    Reason                 Age                   From                                                                                             Message
  ----    ------                 ----                  ----                                                                                             -------
  Normal  Provisioning           6m6s                  csi.simplivity.hpe.com_svt-csi-controller-5844ff4c8c-jgv9k_2164c1a6-89af-4837-b6b6-c10015aa07c6  External provisioner is provisioning volume for claim "default/www-web-restore-1"
  Normal  ExternalProvisioning   5m13s (x5 over 6m5s)  persistentvolume-controller                                                                      waiting for a volume to be created, either by external provisioner "csi.simplivity.hpe.com" or manually created by system administrator
  Normal  ProvisioningSucceeded  5m10s                 csi.simplivity.hpe.com_svt-csi-controller-5844ff4c8c-jgv9k_2164c1a6-89af-4837-b6b6-c10015aa07c6  Successfully provisioned volume pvc-72fb5f0e-5a93-44fd-a5fe-c82339093115

Deleting a Volume Snapshot

Snapshots can be deleted when no longer needed.

Snapshot Delete Procedure

The VolumeSnapshotContent object Deletion Policy determines whether or not the underlying VolumeSnapshotContent object will be deleted or not when the VolumeSnapshot is deleted. If it is set to Retain then both the VolumeSnapshot and VolumeSnapshotContent object must be deleted to fully delete the snapshot. In this case, it is set to Delete and thus we only need to remove the VolumeSnapshot object.

$ kubectl describe volumesnapshotcontent snapcontent-7fa13b4b-f370-40c4-9946-4c7e2c72dcdc
Name:         snapcontent-7fa13b4b-f370-40c4-9946-4c7e2c72dcdc
Namespace:
Labels:       <none>
Annotations:  <none>
API Version:  snapshot.storage.k8s.io/v1beta1
Kind:         VolumeSnapshotContent
Metadata:
  Creation Timestamp:  2020-06-12T19:00:42Z
  Finalizers:
    snapshot.storage.kubernetes.io/volumesnapshotcontent-bound-protection
  Generation:        1
  Resource Version:  8840185
  Self Link:         /apis/snapshot.storage.k8s.io/v1beta1/volumesnapshotcontents/snapcontent-7fa13b4b-f370-40c4-9946-4c7e2c72dcdc
  UID:               15f8f342-e9d9-4039-8c26-4ec321a8f60e
Spec:
  Deletion Policy:  Delete
  Driver:           csi.simplivity.hpe.com
  Source:
    Volume Handle:             202797ef-40e3-41ba-a8b1-3850cfc93901
  Volume Snapshot Class Name:  hpe-simplivity-snapclass
  Volume Snapshot Ref:
    API Version:       snapshot.storage.k8s.io/v1beta1
    Kind:              VolumeSnapshot
    Name:              www-web-snap-1
    Namespace:         default
    Resource Version:  8840043
    UID:               7fa13b4b-f370-40c4-9946-4c7e2c72dcdc
Status:
  Creation Time:    1591988468000000000
  Ready To Use:     true
  Restore Size:     1073741824
  Snapshot Handle:  996730a3-6005-4f4c-a758-5203892faa0b
Events:             <none>

Delete the VolumeSnapshot object.

$ kubectl delete volumesnapshot www-web-snap-1
volumesnapshot.snapshot.storage.k8s.io "www-web-snap-1" deleted

Verify the snapshot and content are removed.

$ kubectl get volumesnapshot www-web-snap-1
Error from server (NotFound): volumesnapshots.snapshot.storage.k8s.io "www-web-snap-1" not found
$ kubectl get volumesnapshotcontent snapcontent-7fa13b4b-f370-40c4-9946-4c7e2c72dcdc
Error from server (NotFound): volumesnapshotcontents.snapshot.storage.k8s.io "snapcontent-7fa13b4b-f370-40c4-9946-4c7e2c72dcdc" not found

Verify that the backup has been deleted from HPE SimpliVity.

$ svt-backup-show --pv pvc-e3fe7f3b-e00a-4b0d-9d65-89c3564081be_fcd --datastore svt-ds
No backups found.