Alauda Container Platform

Cloning a PVC

PVC cloning creates a new PersistentVolumeClaim (PVC) with a copy of the data in an existing PVC. Use a clone when an application needs an independent writable copy of data, for example, to prepare a test environment from existing application data.

A clone is created directly from a source PVC. In contrast, a volume snapshot captures the PVC at a point in time and can be retained or used later to create a PVC. Choose a clone for a direct copy and a volume snapshot when you need a recoverable point-in-time copy.

NOTE

ACP does not currently provide a UI for cloning PVCs. Create the cloned PVC by applying a YAML manifest with kubectl.

TOC

PrerequisitesACP storage supportCreate a cloned PVCVerify the clone

Prerequisites

  • PVC cloning is available only for dynamically provisioned PVCs whose CSI driver supports cloning. Static provisioning does not support PVC cloning.
  • The source PVC is in the Bound phase and is not in use.
  • The source and target PVCs are in the same namespace.
  • The target PVC requests storage capacity that is at least the source PVC capacity.
  • The source and target PVCs use the same volume mode. The target access mode must be supported by its storage class and CSI driver.

ACP storage support

The target PVC can use a different storage class only when the CSI driver and storage backend support cloning from the source volume to that storage class. Kubernetes does not validate this backend compatibility.

Storage typePVC clone supportStorage class requirements
CephRBD Block StorageSupportedThe source and target must use compatible RBD storage classes in the same Ceph cluster. A different RBD storage class, including one that uses a different pool, can be used when Ceph CSI supports the selected backend configuration.
CephFS File StorageSupportedThe source and target must use compatible storage classes for the same Ceph cluster and CephFS file system.
TopoLVMSupported for thin-provisioned volumesUse the same storage class for the source and target. A clone created with a different storage class can fail to schedule when its device class differs from the source.
NFS Shared StorageNot supportedNFS Shared Storage does not support PVC cloning.

For information about creating a source PVC, see Creating PVCs.

Create a cloned PVC

Create a manifest named clone-pvc.yaml. Replace the namespace, storage class, access mode, volume mode, capacity, and PVC names with values supported by your storage driver. See ACP storage support before choosing a target storage class.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: cloned-pvc
  namespace: application-space
spec:
  storageClassName: clone-capable-csi
  accessModes:
    - ReadWriteOnce
  volumeMode: Filesystem
  resources:
    requests:
      storage: 10Gi
  dataSource:
    apiGroup: ""
    kind: PersistentVolumeClaim
    name: source-pvc

Apply the manifest:

kubectl apply -f clone-pvc.yaml

Verify the clone

Check the status of the target PVC:

kubectl get pvc cloned-pvc -n application-space

When the STATUS column shows Bound, the storage driver has provisioned and bound the cloned volume. You can then mount cloned-pvc in a workload and verify that the expected source data is available.

Inspect the PVC events for provisioning or cloning errors:

kubectl describe pvc cloned-pvc -n application-space

If the PVC remains in Pending or creation fails, review the events shown by this command. Confirm that the selected storage class supports PVC cloning and that the source PVC, namespace, requested capacity, volume mode, and access mode meet the prerequisites.