virt-migration-workflow.adoc

Detailed migration workflow

You can use the detailed migration workflow to troubleshoot a failed migration.

The workflow describes the following steps:

Warm Migration or migration to a remote {ocp-name} cluster:

1. When you create the Migration custom resource (CR) to run a migration plan, the Migration Controller service creates a DataVolume CR for each source VM disk.

   For each VM disk:

2. The Containerized Data Importer (CDI) Controller service creates a persistent volume claim (PVC) based on the parameters specified in the DataVolume CR.



3. If the StorageClass has a dynamic provisioner, the persistent volume (PV) is dynamically provisioned by the StorageClass provisioner.

4. The CDI Controller service creates an importer pod.

5. The importer pod streams the VM disk to the PV.

   After the VM disks are transferred:

6. The Migration Controller service creates a conversion pod with the PVCs attached to it when importing from VMWare.

   The conversion pod runs virt-v2v, which installs and configures device drivers on the PVCs of the target VM.

7. The Migration Controller service creates a VirtualMachine CR for each source virtual machine (VM), connected to the PVCs.

8. If the VM ran on the source environment, the Migration Controller powers on the VM, the KubeVirt Controller service creates a virt-launcher pod and a VirtualMachineInstance CR.

   The virt-launcher pod runs QEMU-KVM with the PVCs attached as VM disks.

Cold migration from {rhv-short} or {osp} to the local {ocp-name} cluster:

1. When you create a Migration custom resource (CR) to run a migration plan, the Migration Controller service creates for each source VM disk a PersistentVolumeClaim CR, and an OvirtVolumePopulator when the source is {rhv-short}, or an OpenstackVolumePopulator CR when the source is {osp}.

   For each VM disk:

2. The Populator Controller service creates a temporarily persistent volume claim (PVC).

3. If the StorageClass has a dynamic provisioner, the persistent volume (PV) is dynamically provisioned by the StorageClass provisioner.

   • The Migration Controller service creates a dummy pod to bind all PVCs. The name of the pod contains pvcinit.

4. The Populator Controller service creates a populator pod.

5. The populator pod transfers the disk data to the PV.

   After the VM disks are transferred:

6. The temporary PVC is deleted, and the initial PVC points to the PV with the data.

7. The Migration Controller service creates a VirtualMachine CR for each source virtual machine (VM), connected to the PVCs.

8. If the VM ran on the source environment, the Migration Controller powers on the VM, the KubeVirt Controller service creates a virt-launcher pod and a VirtualMachineInstance CR.

   The virt-launcher pod runs QEMU-KVM with the PVCs attached as VM disks.

Cold migration from VMWare to the local {ocp-name} cluster:

1. When you create a Migration custom resource (CR) to run a migration plan, the Migration Controller service creates a DataVolume CR for each source VM disk.

   For each VM disk:

2. The Containerized Data Importer (CDI) Controller service creates a blank persistent volume claim (PVC) based on the parameters specified in the DataVolume CR.



3. If the StorageClass has a dynamic provisioner, the persistent volume (PV) is dynamically provisioned by the StorageClass provisioner.

For all VM disks:

1. The Migration Controller service creates a dummy pod to bind all PVCs. The name of the pod contains pvcinit.

2. The Migration Controller service creates a conversion pod for all PVCs.

3. The conversion pod runs virt-v2v, which converts the VM to the KVM hypervisor and transfers the disks' data to their corresponding PVs.

   After the VM disks are transferred:

4. The Migration Controller service creates a VirtualMachine CR for each source virtual machine (VM), connected to the PVCs.

5. If the VM ran on the source environment, the Migration Controller powers on the VM, the KubeVirt Controller service creates a virt-launcher pod and a VirtualMachineInstance CR.

   The virt-launcher pod runs QEMU-KVM with the PVCs attached as VM disks.