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Cloning a virtual machine disk into a new DataVolume

You can clone the PersistentVolumeClaim (PVC) of a virtual machine disk into a new DataVolume by referencing the source PVC in your DataVolume configuration file.

Cloning operations between different volume modes are not supported. The volumeMode values must match in both the source and target specifications.

For example, if you attempt to clone from a PersistentVolume (PV) with volumeMode: Block to a PV with volumeMode: Filesystem, the operation fails with an error message.

Prerequisites

About DataVolumes

DataVolume objects are custom resources that are provided by the Containerized Data Importer (CDI) project. DataVolumes orchestrate import, clone, and upload operations that are associated with an underlying PersistentVolumeClaim (PVC). DataVolumes are integrated with KubeVirt, and they prevent a virtual machine from being started before the PVC has been prepared.

Cloning the PersistentVolumeClaim of a virtual machine disk into a new DataVolume

You can clone a PersistentVolumeClaim (PVC) of an existing virtual machine disk into a new DataVolume. The new DataVolume can then be used for a new virtual machine.

When a DataVolume is created independently of a virtual machine, the lifecycle of the DataVolume is independent of the virtual machine. If the virtual machine is deleted, neither the DataVolume nor its associated PVC is deleted.
Prerequisites

  • Determine the PVC of an existing virtual machine disk to use. You must power down the virtual machine that is associated with the PVC before you can clone it.

  • Install the OpenShift CLI (oc).

Procedure

  1. Examine the virtual machine disk you want to clone to identify the name and namespace of the associated PVC.

  2. Create a YAML file for a DataVolume object that specifies the name of the new DataVolume, the name and namespace of the source PVC, and the size of the new DataVolume.

    For example:

    apiVersion: cdi.kubevirt.io/v1alpha1
kind: DataVolume
metadata:
  name: <cloner-datavolume> (1)
spec:
  source:
    pvc:
      namespace: "<source-namespace>" (2)
      name: "<my-favorite-vm-disk>" (3)
  pvc:
    accessModes:
      - ReadWriteOnce
    resources:
      requests:
        storage: <2Gi> (4)
    1 The name of the new DataVolume.
    2 The namespace where the source PVC exists.
    3 The name of the source PVC.
    4 The size of the new DataVolume. You must allocate enough space, or the cloning operation fails. The size must be the same as or larger than the source PVC.

  3. Start cloning the PVC by creating the DataVolume:

    $ oc create -f <cloner-datavolume>.yaml

    DataVolumes prevent a virtual machine from starting before the PVC is prepared, so you can create a virtual machine that references the new DataVolume while the PVC clones.

Template: DataVolume clone configuration file

example-clone-dv.yaml

apiVersion: cdi.kubevirt.io/v1alpha1
kind: DataVolume
metadata:
  name: "example-clone-dv"
spec:
  source:
      pvc:
        name: source-pvc
        namespace: example-ns
  pvc:
    accessModes:
      - ReadWriteOnce
    resources:
      requests:
        storage: "1G"

CDI supported operations matrix

This matrix shows the supported CDI operations for content types against endpoints, and which of these operations requires scratch space.

Content types HTTP HTTPS HTTP basic auth Registry Upload

KubeVirt(QCOW2)

✓ QCOW2
✓ GZ*
✓ XZ*

✓ QCOW2**
✓ GZ*
✓ XZ*

✓ QCOW2
✓ GZ*
✓ XZ*

✓ QCOW2*
□ GZ
□ XZ

✓ QCOW2*
✓ GZ*
✓ XZ*

KubeVirt (RAW)

✓ RAW
✓ GZ
✓ XZ

✓ RAW
✓ GZ
✓ XZ

✓ RAW
✓ GZ
✓ XZ

✓ RAW*
□ GZ
□ XZ

✓ RAW*
✓ GZ*
✓ XZ*

✓ Supported operation

□ Unsupported operation

* Requires scratch space

** Requires scratch space if a custom certificate authority is required