Configuring PVC Changes

• 1: Creating a PVC Change
• 1.1: Preparing a PVC Change File
• 1.2: Creating a PVC Change Resource
• 2: Querying a PVC Change
• 3: Deleting a PVC Change

1 - Creating a PVC Change

Prerequisites

The storage backends associated with the PVC to be changed are HyperMetro storage backends. If they are not HyperMetro storage backends, configure them by following the instructions in Manually Updating a Storage Backend.

1.1 - Preparing a PVC Change File

PVC Change File Description

The sample template of the PVC change file is /examples/volumemodifyclaim.yaml. The following table lists the configuration items.

Table 1 Parameter description

• The spec.source.kind and spec.source.name parameters are used to specify the volume change scope. For example, if they are set to a StorageClass and the corresponding name respectively, all PVCs in the Bound state provisioned using the target StorageClass will be changed.
• After all associated PVCs are changed, Huawei CSI will replace the original StorageClass and add the spec.parameters parameter of the VolumeModifyClaim so that the PVCs meet the StorageClass definition.

For details about the configuration in typical scenarios, see the following example:

Changing a Common Volume to a HyperMetro Volume

The following is an example of changing a common volume to a HyperMetro volume:

apiVersion: xuanwu.huawei.io/v1
kind: VolumeModifyClaim
metadata:
  name: myvmc
spec:
  source:
    kind: StorageClass
    name: mysc
  parameters:
    hyperMetro: "true"

1.2 - Creating a PVC Change Resource

This section describes how to create a PVC change resource based on a configured PVC change file.

• Only the HyperMetro active-active (AA) mode is supported.
• When a common volume is changed to a HyperMetro volume, only the storage volume at the primary site can be changed.
• Do not use Huawei CSI to manage a PVC during PVC change resource creation.
• Multiple VolumeModifyClaim resources cannot be created for the same PVC. If the target PVC needs to be changed for multiple times, perform the changes one by one.

Procedure

1. Use a remote access tool, such as PuTTY, to log in to any master node in the Kubernetes cluster through the management IP address.

2. Run the following command to create a PVC change.

   kubectl create -f volumemodifyclaim.yaml 
   

3. Query the creation result by following the instructions in Querying a PVC Change.

2 - Querying a PVC Change

This section describes how to use Kubectl to query the PVC change status. Currently, Huawei CSI provides the following APIs through CRD.

Querying a VolumeModifyClaim

To query a VolumeModifyClaim using kubectl, perform the following steps.

1. Use a remote access tool, such as PuTTY, to log in to any master node in the Kubernetes cluster through the management IP address.

2. Run the following command to query a PVC change. In the command, vmc-name indicates the name of the VolumeModifyClaim resource.

   kubectl get volumemodifyclaims <vmc-name> -owide
   

   The following is an example of the command output.

   NAME    STATUS      READY   SOURCEKIND     SOURCENAME   STARTEDAT              COMPLETEDAT            AGE
   myvmc   Completed   1/1     StorageClass   mysc         2024-06-06T03:19:13Z   2024-06-06T03:19:16Z   2m2s
   

   Table 1 Command output description

   Parameter	Description
   NAME	VolumeModifyClaim resource name.
   STATUS	VolumeModifyClaim resource status. The value can be: Pending: initial status. Creating: The VolumeModifyClaim has completed basic verification and the server has received the change task, but the task has not been completed. Completed: All associated PVCs are changed. Rollback: When associated PVCs are partially changed, a user deletes PVCs. Deleting: When all associated PVCs are changed, a user deletes PVCs.
   READY	Ratio of the number of changed PVCs to the total number of PVCs that need to be changed.
   SOURCEKIND	Data source type, for example, StorageClass.
   SOURCENAME	Data source name, for example, StorageClass name.
   STARTEDAT	Change start time, that is, the timestamp when the server receives the task and starts to process the task.
   COMPLETEDAT	Change completion time, that is, the timestamp when the changes of all associated PVCs are complete. This parameter exists only when STATUS is Completed.
   AGE	Lifetime of a VolumeModifyClaim from the time when it is created to the current time.

You can use kubectl to view the Events information of a VolumeModifyClaim. If a VolumeModifyClaim cannot meet the creation requirements or an error occurs during the creation, the server will record the Events information. The following command is used as an example:

kubectl describe volumemodifyclaims local-to-hypermetro 

Querying a VolumeModifyContent

A VolumeModifyContent is created using a VolumeModifyClaim and records the change details of a single PVC. To query a VolumeModifyContent using kubectl, perform the following steps:

1. Use a remote access tool, such as PuTTY, to log in to any master node in the Kubernetes cluster through the management IP address.

2. Run the following command to query a PVC change. In the command, myvmc-uid indicates the VolumeModifyContent resource name.

   kubectl get volumemodifycontents myvmc-uid  -owide
   

   The following is an example of the command output.

   NAME         STATUS      MODIFYCLAIMNAME     SOURCEVOLUME   STARTEDAT              COMPLETEDAT            AGE
   myvmc-uid    Completed   myvmc               default/mypvc  2024-06-06T03:19:07Z   2024-06-06T03:19:09Z   36m
   

   Table 2 Command output description

   Parameter	Description
   NAME	VolumeModifyContent resource name. The format is VolumeModifyClaim name-UID of the associated PVC.
   STATUS	VolumeModifyContent resource status. The value can be: Pending: initial status. Creating: The VolumeModifyContent has completed basic verification and the server has received the change task, but the task has not been completed. Completed: The associated PVC is changed. Rollback: The PVC change is being rolled back.
   MODIFYCLAIMNAME	Name of the associated VolumeModifyClaim.
   SOURCEVOLUME	Information about the associated PVC. The format is Namespace name/PVC name.
   STARTEDAT	PVC change start time, that is, the timestamp when the server receives the task and starts to process the task.
   COMPLETEDAT	PVC change completion time, that is, the timestamp when the changes of all associated PVCs are complete. This parameter exists only when STATUS is Completed.
   AGE	Lifetime of a VolumeModifyContent from the time when it is created to the current time.

You can use kubectl to view the Events information of a VolumeModifyContent. If a VolumeModifyContent cannot meet the creation requirements or an error occurs during the PVC change, the server will record the Events information. The following command is used as an example:

kubectl describe volumemodifycontents myvmc-uid

3 - Deleting a PVC Change

• If STATUS of a VolumeModifyClaim is Creating, deleting the VolumeModifyClaim resource will delete the created resource on the storage side and then remove the cluster resource. After the deletion, if you continue to use the original StorageClass for PVC management, you need to restore the associated storage backend to a non-HyperMetro storage backend.
• If STATUS of a VolumeModifyClaim is Pending or Completed, deleting the VolumeModifyClaim resource will only remove the cluster resource and will not delete the created resource on the storage side (that is, there is not interaction with the storage side).
• VolumeModifyContent resources are managed by VolumeModifyClaim. Do not manually manage VolumeModifyContent resources.
• If some PVCs among the PVCs to be changed meet the change requirements and the batch change fails, all PVC changes will be removed. As a result, the PVCs that meet the change requirements will not meet the change requirements.
• If a PVC to be changed has been manually managed on the storage side, the change may fail. Do not manually manage storage volumes when using the change feature.

This section describes how to use kubectl to delete a PVC change. The procedure is as follows.

Procedure

1. Use a remote access tool, such as PuTTY, to log in to any master node in the Kubernetes cluster through the management IP address.

2. Run the following command to delete a PVC change. In the command, vmc-name indicates the name of the VolumeModifyClaim resource.

   kubectl delete volumemodifyclaims <vmc-name>
   

3. Query the deletion result by following the instructions in Creating a PVC Change Resource.