Expand Cloud Disk PVCs Online in ACK Serverless - Container Service for Kubernetes

As application data grows, cloud disk storage on an ACK Serverless cluster can run out of capacity. For dynamically provisioned cloud disk persistent volumes, you can expand storage without stopping pods—keeping your workloads uninterrupted throughout the process.

Limitations

The following limitations apply to cloud disk persistent volume expansion on ACK Serverless clusters:

InlineVolume is not supported. Only volumes attached through a PersistentVolumeClaim (PVC) can be expanded.
Static provisioning is not supported. The persistent volume (PV) bound to the PVC must be associated with a StorageClass (dynamically provisioned only).
Basic disks cannot be expanded.
Cross-type expansion is not supported. Expand only within the capacity range of the current cloud disk type. Do not change the cloud disk type.

Prerequisites

Before you begin, make sure that you have:

The Container Storage Interface (CSI) storage component installed and upgraded to the latest version. For more information, see Install and Upgrade the csi-provisioner Component.
A pod in Running state with the cloud disk attached.
A StorageClass with allowVolumeExpansion: true. This is the default. If you did not set allowVolumeExpansion when creating the StorageClass, the system sets it to true automatically.
(Optional) A cloud disk snapshot for backup. Create one before expanding to prevent data loss from unexpected issues. Delete the snapshot after the expansion completes to avoid ongoing snapshot fees. For more information, see Manually Create a Single Snapshot.

Enable online cloud disk expansion

ACK Serverless clusters do not support cloud disk expansion by default. Enable it by setting enablePVCController to true in the eci-profile ConfigMap.

Use kubectl

Connect to the cluster. For more information, see Obtain Cluster KubeConfig and Connect to the Cluster Using kubectl.

Edit eci-profile.

kubectl edit configmap eci-profile -n kube-system

Set enablePVCController to true and save.

Use the console

Log on to the Container Service Management Console. In the left navigation pane, click Clusters.
Click the name of your cluster. In the left navigation pane, choose Configurations > ConfigMaps.
Select the kube-system namespace.
Find eci-profile and click Edit.
Set enablePVCController to true, then click OK.

Expand a cloud disk online

Connect to the cluster. For more information, see Obtain Cluster KubeConfig and Connect to the Cluster Using kubectl.

Check the current disk usage. The following example uses pod test-0 with mount path /data.

kubectl exec test-0 -- df /data

Expected output:

Filesystem     1K-blocks  Used Available Use% Mounted on
/dev/vdb        25626852    24  25610444   1% /data

List PVCs to identify the one to expand.

kubectl get pvc

Expected output. In this example, the PVC test-pvc is bound to cloud disk d-uf68pljc3sppvhss**** with a capacity of 25 GiB.

NAME       STATUS   VOLUME                   CAPACITY   ACCESS MODES   STORAGECLASS   VOLUMEATTRIBUTESCLASS   AGE
test-pvc   Bound    d-uf68pljc3sppvhss****   25Gi       RWO            test-sc        <unset>                 7m38s

Patch the PVC to request the new capacity. The following example expands test-pvc to 30 GiB.
```
kubectl patch pvc test-pvc -p '{"spec":{"resources":{"requests":{"storage":"30Gi"}}}}'
```

After a period, verify that expansion succeeded.

Check that the PVC capacity has updated.

kubectl get pvc

Expected output. The cloud disk d-uf68pljc3sppvhss**** now shows 30 GiB.

NAME       STATUS   VOLUME                   CAPACITY   ACCESS MODES   STORAGECLASS   VOLUMEATTRIBUTESCLASS   AGE
test-pvc   Bound    d-uf68pljc3sppvhss****   30Gi       RWO            test-sc        <unset>                 18m

Confirm the new capacity is visible inside the pod.

kubectl exec test-0 -- df /data

Expected output:

Filesystem     1K-blocks  Used Available Use% Mounted on
/dev/vdb        30787492    24  30771084   1% /data