Container Service for Kubernetes:Expand a dynamically provisioned volume without service interruptions

Usage notes

• Data backup

  Before you expand a disk volume, create a snapshot for the disk in case data issues occur during disk volume expansion.

• Scenarios

  • You can expand only dynamically provisioned persistent volumes (PVs) without service interruptions, which are mounted by using persistent volume claims (PVCs) that contain the StorageClassName parameter.

  • You cannot expand disk volumes of the inline type. This type of disk volume is not created by using PVs and PVCs.

  • You cannot expand volumes that are associated with basic disks without service interruptions.

  • Specify AllowVolumeExpansion: True for the StorageClass. The AllowVolumeExpansion parameter is automatically set to True for StorageClasses that are created by ACK. For StorageClasses that are manually created, you must manually set the AllowVolumeExpansion parameter to True.

  • Pods must remain in the Running state during volume expansion.

• Plug-in version

  Make sure that the CSI plug-in is updated to the latest version.

Grant the ResizeDisk permission to the Resource Access Management (RAM) role of the cluster

Before you expand a disk volume without service interruptions, you must grant the ResizeDisk permission to the RAM role of the cluster. Perform the following steps to grant the ResizeDisk permission based on the cluster type and the volume plug-in that is used:

ACK dedicated clusters that use CSI plug-in

1. Log on to the ACK console.

2. In the left-side navigation pane, click Clusters.

3. On the Clusters page, click Details in the Actions column of the cluster that you want to manage.

4. In the left-side navigation pane, click Cluster Information.

5. Click the Cluster Resources tab and click the hyperlink next to Master RAM Role.

6. In the RAM console, grant the ResizeDisk permission to the RAM role. For more information about how to grant the permissions, see Modify the document and description of a custom policy.

ACK dedicated clusters that use FlexVolume or ACK managed clusters

Perform the preceding Step 1 to Step 4 and click the hyperlink next to Master RAM Role.

Expand a disk volume without starting the application pods

1. Use a command-line tool to connect to the ACK cluster. For more information, see Step 2: Select a type of cluster credentials.

   In this example, the pod that you want to manage is in the following state.

   Run the following command to query pod information:

   kubectl get pod

   Expected output:

   <YOUR-POD-NAME>         1/1     Running   0          42s

   Run the following command to query the volume that is mounted to the pod:

   kubectl exec <YOUR-POD-NAME>  -- df /data

   Expected output:

   Filesystem     1K-blocks  Used   Available Use% Mounted on
   /dev/vdb       20511312   45080  20449848  1%   /data

   Run the following command to query PVC information:

   kubectl get pvc

   Expected output:

   NAME              STATUS   VOLUME                   CAPACITY   ACCESS MODES   STORAGECLASS                     AGE
   <your-PVC-name>   Bound    d-wz9hpoifm43yn9zi****   20Gi       RWO            alicloud-disk-topology-alltype   57s

   Run the following command to query PV information:

   kubectl get pv

   Expected output:

   NAME                     CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS     CLAIM                     STORAGECLASS                     REASON   AGE
   d-wz9hpoifm43yn9zi****   20Gi       RWO            Delete           Bound      default/<your-PVC-name>   alicloud-disk-topology-alltype            65s

2. Run the following command to expand the disk volume when the requirements in the Usage notes section are met:

   kubectl patch pvc <your-PVC-name> -p '{"spec":{"resources":{"requests":{"storage":"30Gi"}}}}'

   Wait 1 minute and then check whether the PV is expanded.

   Run the following command to query PV information:

   kubectl get pv d-wz9hpoifm43yn9zi****

   Expected output:

   NAME                     CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                    STORAGECLASS                     REASON   AGE
   d-wz9hpoifm43yn9zi****   30Gi       RWO            Delete           Bound    default/<your-PVC-name>   alicloud-disk-topology-alltype           5m23s

   Run the following command to query PVC information:

   kubectl get pvc

   Expected output:

   NAME             STATUS   VOLUME                   CAPACITY   ACCESS MODES   STORAGECLASS                     AGE
   <your-PVC-name>   Bound    d-wz9hpoifm43yn9zi****   30Gi       RWO           alicloud-disk-topology-alltype   5m10s

   Run the following command to query the volume that is mounted to the pod:

   kubectl exec <YOUR-POD-NAME> -- df /data

   Expected output:

   Filesystem     1K-blocks  Used   Available  Use%  Mounted on
   /dev/vdb       30832548   45036  30771128   1%    /data

   To expand a disk volume without service interruptions, you need to only run the preceding command.

References

For information about how to automatically expand a disk volume when the utilization of the disk volume exceeds a specified threshold value, see Automatically expand a disk volume (public preview).