Container Service for Kubernetes:Expand a cloud disk volume online

Expand a disk volume using kubectl

The following example uses a disk volume created in Create a dynamically provisioned disk volume. Modifying the PVC triggers the CSI plug-in to resize the underlying disk and expand the filesystem online — the pod keeps running throughout.

1. Connect to your cluster. See Obtain the kubeconfig file of a cluster and use kubectl to connect to the cluster or Use kubectl on Workbench or Cloud Shell to connect to ACK clusters.

2. Verify that the pod is in the Running state.

   kubectl get pod -l app=nginx

   Expected output:

   NAME          READY   STATUS    RESTARTS   AGE
   disk-test-0   1/1     Running   0          23h

3. Check the current disk usage and PVC.

   Important

   For a statically provisioned disk volume, make sure that storageClassName in the PVC is not blank and that a StorageClass with that name exists in the cluster. If no matching StorageClass exists, create one with the existing disk's attributes and set allowVolumeExpansion: true.

   kubectl exec disk-test-0 -- df -h /data

   Expected output:

   Filesystem      Size  Used Avail Use% Mounted on
   /dev/vdb         20G   24K   20G   1% /data

   kubectl get pvc

   Expected output (PVC disk-pvc is bound with 20 GiB capacity):

   NAME       STATUS   VOLUME                   CAPACITY   ACCESS MODES   STORAGECLASS                            VOLUMEATTRIBUTESCLASS   AGE
   disk-pvc   Bound    d-uf6axyb1er071h6o****   20Gi       RWO            alicloud-disk-wait-for-first-consumer   <unset>                 23h

4. Confirm the StorageClass has allowVolumeExpansion: true.

   kubectl get sc alicloud-disk-wait-for-first-consumer -o yaml

   Expected output:

   allowVolumeExpansion: true
   apiVersion: storage.k8s.io/v1
   kind: StorageClass
   metadata:
     creationTimestamp: "2025-01-21T08:48:26Z"
     name: alicloud-disk-wait-for-first-consumer
     resourceVersion: "59936"
     uid: 5bdb798e-5888-40df-9f91-259ee8510f34
   parameters:
     type: cloud_auto,cloud_essd,cloud_ssd
   provisioner: diskplugin.csi.alibabacloud.com
   reclaimPolicy: Retain
   volumeBindingMode: WaitForFirstConsumer

5. Patch the PVC to request 30 GiB.

   kubectl patch pvc disk-pvc -p '{"spec":{"resources":{"requests":{"storage":"30Gi"}}}}'

6. Wait for a minute, then verify the new capacity.

   kubectl get pvc

   Expected output:

   NAME       STATUS   VOLUME                   CAPACITY   ACCESS MODES   STORAGECLASS                            VOLUMEATTRIBUTESCLASS   AGE
   disk-pvc   Bound    d-uf6axyb1er071h6o****   30Gi       RWO            alicloud-disk-wait-for-first-consumer   <unset>                 23h

   kubectl exec disk-test-0 -- df -h /data

   Expected output:

   Filesystem      Size  Used Avail Use% Mounted on
   /dev/vdb         30G   24K   30G   1% /data

Expand a disk volume using the ACK console

1. Log on to the ACK console and click Clusters.

2. Click the cluster name to go to the cluster management page.

3. Verify the pod state and find the PVC.

   1. In the left-side navigation pane, choose Workloads > StatefulSets.

   2. Click the application name. On the Pods tab, confirm the pod is in the Running state.

   3. Click the pod name. On the Volumes tab, note the PVC used by the pod.

4. Confirm the StorageClass has expansion enabled.

   1. In the left-side navigation pane, choose Volumes > Storage Classes.

   2. Find the StorageClass used by the disk volume and click View in YAML.

   3. Confirm allowVolumeExpansion: true is present.

5. Expand the PVC.

   1. In the left-side navigation pane, choose Volumes > Persistent Volume Claims.

   2. Find the PVC and click Expand.

   3. Enter the new capacity, select I understand and agree to the preceding operations, and click OK.

   4. Wait for expansion to complete, then verify the PVC shows the new capacity.