Understanding node maintenance mode

Placing a node into maintenance marks the node as unschedulable and drains all the virtual machines and pods from it. Virtual machine instances that have a LiveMigrate eviction strategy are live migrated to another node without loss of service. This eviction strategy is configured by default in virtual machine created from common templates but must be configured manually for custom virtual machines.

Virtual machine instances without an eviction strategy will be deleted on the node and recreated on another node.

NFS shared volumes are the only shared data volume type supported for live migration in container-native virtualization 2.0.

Place a node into maintenance from either the web console or the CLI.

Setting a node to maintenance mode in the web console

Set a node to maintenance mode using the Options menu kebab found on each node in the ComputeNodes list, or using the Actions control of the Node Details screen.

Procedure
  1. In the container-native virtualization console, click ComputeNodes.

  2. You can set the node to maintenance from this screen, which makes it easier to perform actions on multiple nodes in the one screen or from the Node Details screen where you can view comprehensive details of the selected node:

    • Click the Options menu kebab at the end of the node and select Start Maintenance.

    • Click the node name to open the Node Details screen and click ActionsStart Maintenance.

  3. Click Start Maintenance in the confirmation window.

The node will live migrate virtual machine instances that have the liveMigration eviction strategy, and the node is no longer schedulable. All other pods and virtual machines on the node are deleted and recreated on another node.

Setting a node to maintenance mode in the CLI

Set a node to maintenance mode by creating a NodeMaintenance Custom Resource (CR) object that references the node name and the reason for setting it to maintenance mode.

Procedure
  1. Create the node maintenance CR configuration. This example uses a CR that is called node02-maintenance.yaml:

    apiVersion: kubevirt.io/v1alpha1
    kind: NodeMaintenance
    metadata:
      name: node02-maintenance
    spec:
      nodeName: node02
      reason: "Replacing node02"
  2. Create the NodeMaintenance object in the cluster:

    $ oc apply -f <node02-maintenance.yaml>

The node live migrates virtual machine instances that have the liveMigration eviction strategy, and taint the node so that it is no longer schedulable. All other pods and virtual machines on the node are deleted and recreated on another node.