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Enabling cross-cluster live migration for virtual machines

Cross-cluster live migration enables users to move a virtual machine (VM) workload from one OKD cluster to another cluster without disruption. You enable cross-cluster live migration by setting cluster feature gates in OpenShift Virtualization and Migration Toolkit for Virtualization (MTV).

Prerequisites

  • OpenShift Virtualization 4.20 or later must be installed.

  • The OKD and OpenShift Virtualization minor release versions must match. For example, if the OKD version is 4.20.0, the OpenShift Virtualization must also be 4.20.0.

  • Two OKD clusters are required, and the migration network for both clusters must be connected to the same L2 network segment.

  • You must have cluster administration privileges and appropriate RBAC privileges to manage VMs on both clusters.

Cross-cluster live migration is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

For more information about the support scope of Red Hat Technology Preview features, see Technology Preview Features Support Scope.

Setting a live migration feature gate for each cluster in OpenShift Virtualization

To enable cross-cluster live migration, you must set a feature gate for each of the two clusters in OpenShift Virtualization.

Prerequisites

  • You have installed the OpenShift CLI (oc).

  • You must have cluster admin privileges.

  • The virt-synchronization-controller pods must be running.

Procedure

  • Set the feature gate by running the following command for each cluster:

    $ oc patch hyperconverged kubevirt-hyperconverged -n openshift-cnv --type json -p '[{"op":"replace", "path": "/spec/featureGates/decentralizedLiveMigration", "value": true}]'
Verification

  • To verify that the feature gate enablement is successful for each cluster, run the following command in the OpenShift Virtualization namespace to locate the synchronization pods:

    $ oc get -n {CNVNamespace} pod | grep virt-synchronization

    Example output:

    virt-synchronization-controller-898789f8fc-nsbsm      1/1     Running   0               5d1h
virt-synchronization-controller-898789f8fc-vmmfj      1/1     Running   0               5d1h

Setting a live migration feature gate in the Migration Toolkit for Virtualization (MTV)

You enable the OKD live migration feature gate in the Migration Toolkit for Virtualization (MTV) to allow virtual machines to migrate between clusters during cross-cluster live migration. This feature gate must be enabled in both clusters that participate in the migration.

Prerequisites

  • You have installed the OpenShift CLI (oc).

  • You must have cluster admin privileges.

  • The virt-synchronization-controller pods must be running.

Procedure

  • To enable the feature gate by modifying the CR, run the following command:

    $ oc patch ForkliftController forklift-controller -n openshift-mtv --type json -p '[{"op": "add", "path": "/spec/feature_ocp_live_migration", "value": "true"}]'
Verification

  • Verify that the feature gate is enabled by checking the ForkliftController custom resource (CR). Run the following command:

    $ oc get ForkliftController forklift-controller -n openshift-mtv -o yaml

    Confirm that the feature_ocp_live_migration key value is set to true, as shown in the following example:

    apiVersion: forklift.konveyor.io/v1beta1
kind: ForkliftController
metadata:
  name: forklift-controller
  namespace: openshift-mtv
spec:
  feature_ocp_live_migration: "true"
  feature_ui_plugin: "true"
  feature_validation: "true"
  feature_volume_populator: "true"