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Snapshot Management

In Kubernetes, a VolumeSnapshot is a snapshot of a volume on a storage system. The VolumeSnapshot capability provides Kubernetes users with a standard way to replicate the content of a volume at a specified point in time without creating a volume. For example, this function enables database administrators to back up the database before making changes such as editing or deleting.

This section describes how to create a VolumeSnapshot using Huawei CSI. To create a VolumeSnapshot, perform the following steps:

  • Checking information about volume snapshot-dependent components
  • Configuring a VolumeSnapshotClass
  • Configuring a VolumeSnapshot

Prerequisites

  • Compatibility and Features lists storage that support VolumeSnapshot creation. You need to search by the storage type and service type.
  • For details about the Kubernetes versions that support VolumeSnapshot creation, see Table 1 .
  • If you need to use volume snapshots and features associated with volume snapshots in the container environment, perform the operations in Checking Volume Snapshot-Dependent Components to check whether volume snapshot-dependent components have been deployed in your environment and check the api-versions information about volume snapshots.
  • The source PVC exists, and the backend where the PVC resides supports VolumeSnapshot creation.

1 - Configuring a Volume Snapshot

Creating a Volume Snapshot Class

VolumeSnapshotClass provides a way to describe the “classes” of storage when provisioning a VolumeSnapshot. Each VolumeSnapshotClass contains the driver, deletionPolicy, and parameters fields, which are used when a VolumeSnapshot belonging to the class needs to be dynamically provisioned.

The name of a VolumeSnapshotClass object is significant, and is how users can request a particular class. Administrators set the name and other parameters of a class when first creating VolumeSnapshotClass objects, and the objects cannot be updated once they are created.

The following is an example of a VolumeSnapshotClass used by Huawei CSI:

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshotClass
metadata:
  name: mysnapclass
driver: csi.huawei.com
deletionPolicy: Delete

You can modify the parameters according to Table 1 . Currently, Huawei CSI does not support user-defined parameters (parameters) in a VolumeSnapshotClass. Therefore, you are advised to create a VolumeSnapshotClass for all snapshots.

Table 1 VolumeSnapshotClass parameters

Parameter

Description

Remarks

metadata.name

User-defined name of a VolumeSnapshotClass object.

Take Kubernetes v1.22.1 as an example. The value can contain digits, lowercase letters, hyphens (-), and periods (.), and must start and end with a letter or digit.

driver

driver identifier. This parameter is mandatory.

Set this parameter to the driver name set during Huawei CSI installation. The default driver name is csi.huawei.com.

deletionPolicy

Snapshot deletion policy. This parameter is mandatory. The value can be:

  • Delete
  • Retain
  • If the deletion policy is Delete, the snapshot on the storage device will be deleted together with the VolumeSnapshotContent object.
  • If the deletion policy is Retain, the snapshot and VolumeSnapshotContent object on the storage device will be retained.

Procedure

  1. Run the following command to create a VolumeSnapshotClass using the created VolumeSnapshotClass configuration file.

    kubectl create -f mysnapclass.yaml

  2. Run the following command to view the information about the created VolumeSnapshotClass.

    kubectl get volumesnapshotclass

    The following is an example of the command output.

    NAME          DRIVER           DELETIONPOLICY   AGE
mysnapclass   csi.huawei.com   Delete           25s

Creating a Snapshot for a Volume

VolumeSnapshot can be provisioned in two ways: pre-provisioning and dynamic provisioning . Currently, Huawei CSI supports only dynamic provisioning. This section describes how to dynamically provision a VolumeSnapshot using Huawei CSI. The following is an example of the VolumeSnapshot configuration file:

apiVersion: snapshot.storage.k8s.io/v1
kind: VolumeSnapshot
metadata:
  name: mysnapshot
spec:
  volumeSnapshotClassName: mysnapclass
  source:
    persistentVolumeClaimName: mypvc

You can modify the parameters according to Table 2 .

Table 2 VolumeSnapshot parameters

Parameter

Description

Remarks

metadata.name

User-defined name of a VolumeSnapshot object.

Take Kubernetes v1.22.1 as an example. The value can contain digits, lowercase letters, hyphens (-), and periods (.), and must start and end with a letter or digit.

spec.volumeSnapshotClassName

Name of the VolumeSnapshotClass object.

--

spec.source.persistentVolumeClaimName

Name of the source PVC object.

Name of the source PVC of the snapshot

Procedure

  1. Run the following command to create a VolumeSnapshot using the created VolumeSnapshot configuration file.

    kubectl create -f mysnapshot.yaml

  2. Run the following command to view the information about the created VolumeSnapshot.

    kubectl get volumesnapshot

    The following is an example of the command output.

    NAME         READYTOUSE   SOURCEPVC   SOURCESNAPSHOTCONTENT   RESTORESIZE   SNAPSHOTCLASS   SNAPSHOTCONTENT                                    CREATIONTIME   AGE
mysnapshot   true         mypvc                               100Gi         mysnapclass     snapcontent-1009af0a-24c2-4435-861c-516224503f2d   <invalid>      78s

2 - Managing Volume Snapshots

2.1 - Querying a VolumeSnapshot

Viewing a VolumeSnapshotClass

  1. Run the following command to view the information about the created VolumeSnapshotClass.

    kubectl get volumesnapshotclass

    The following is an example of the command output.

    NAME          DRIVER           DELETIONPOLICY   AGE
mysnapclass   csi.huawei.com   Delete           25s

Querying a Volume Snapshot

  1. Run the following command to view the information about the created VolumeSnapshot.

    kubectl get volumesnapshot

    The following is an example of the command output.

    NAME         READYTOUSE   SOURCEPVC   SOURCESNAPSHOTCONTENT   RESTORESIZE   SNAPSHOTCLASS   SNAPSHOTCONTENT                                    CREATIONTIME   AGE
mysnapshot   true         mypvc                               100Gi         mysnapclass     snapcontent-1009af0a-24c2-4435-861c-516224503f2d   <invalid>      78s

2.2 - Creating a PV Using a VolumeSnapshot

Prerequisites

  • Compatibility and Features lists storage that support PVC creation using a VolumeSnapshot. You need to search by the storage type and service type.
  • Kubernetes Feature Matrix lists the Kubernetes versions that support PVC creation using a VolumeSnapshot.
  • A VolumeSnapshot exists, and the backend where the VolumeSnapshot resides supports cloning.

When creating a PVC, you need to specify a VolumeSnapshot as the data source. The following is an example of creating a PVC using a VolumeSnapshot. In this example, mysnapshot is used as the data source and a PVC named myrestore is created.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: myrestore
spec:
  storageClassName: mysc
  dataSource:
    name: mysnapshot
    kind: VolumeSnapshot
    apiGroup: snapshot.storage.k8s.io
  volumeMode: Filesystem
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 100Gi

  • The specified storageClassName must be the same as the StorageClass of the snapshot source volume in dataSource.
  • The capacity of the clone volume must be greater than or equal to that of the snapshot. Equal capacity is recommended.

Procedure

  1. Run the following command to create a PVC based on the configuration file for creating a volume using a snapshot.

    kubectl create -f myrestore.yaml

2.3 - Deleting a VolumeSnapshot

Deleting a VolumeSnapshot

Perform this operation when the volume snapshot is no longer required.

Procedure

  1. Run the following command to view the information about the created VolumeSnapshot.

    kubectl get volumesnapshot

    The following is an example of the command output.

    NAME         READYTOUSE   SOURCEPVC   SOURCESNAPSHOTCONTENT   RESTORESIZE   SNAPSHOTCLASS   SNAPSHOTCONTENT                                    CREATIONTIME   AGE
mysnapshot   true         mypvc                               100Gi         mysnapclass     snapcontent-1009af0a-24c2-4435-861c-516224503f2d   <invalid>      78s

  2. Run the following command to delete the VolumeSnapshot:

    kubectl delete volumesnapshot mysnapshot

    If the following information is displayed, the deletion is successful:

    volumesnapshot.snapshot.storage.k8s.io "mysnapshot" deleted

Deleting a VolumeSnapshotClass

Perform this operation when the VolumeSnapshotClass is not bound to any VolumeSnapshot and the VolumeSnapshotClass is no longer required.

Procedure

  1. Run the following command to view the VolumeSnapshotClass:

    kubectl get vsclass

    The following is an example of the command output.

    NAME          DRIVER           DELETIONPOLICY   AGE
mysnapclass   csi.huawei.com   Delete           25s

  2. Run the following command to delete the StorageClass:

    kubectl delete vsclass mysnapclass

    If the following information is displayed, the deletion is successful:

    volumesnapshotclass.snapshot.storage.k8s.io "mysnapclass" deleted