Chapter 17. Migrating virtual machine instances between Compute nodes

Procedure

1. Access the remote shell for the OpenStackClient pod from your workstation:

   $ oc rsh -n openstack openstackclient

2. List the instances on the source Compute node and locate the ID of the instance or instances that you want to migrate:

    $ openstack server list --host <source> --all-projects

   Replace <source> with the name or ID of the source Compute node.

3. Optional: If you are migrating instances from a source Compute node to perform maintenance on the node, you must disable the node to prevent the scheduler from assigning new instances to the node during maintenance:

    $ openstack compute service set <source> nova-compute --disable

   Replace <source> with the host name of the source Compute node.

4. Exit the OpenStackClient pod:

   $ exit

Procedure

1. Access the remote shell for the OpenStackClient pod from your workstation:

   $ oc rsh -n openstack openstackclient

2. To cold migrate an instance, enter the following command to power off and move the instance:

    $ openstack server migrate <instance> --wait

   • Replace <instance> with the name or ID of the instance to migrate.
   • Specify the --block-migration flag if migrating a locally stored volume.
   • Specify the --wait flag to indicate that you must wait for the migration to complete.
3. While you wait for the instance migration to complete, you can open another terminal window and check the migration status. For more information, see Checking migration status.

4. Check the status of the instance:

    $ openstack server list --all-projects

   A status of "VERIFY_RESIZE" indicates you need to confirm or revert the migration:

   • If the migration worked as expected, confirm it:

      $ openstack server resize --confirm <instance>

     Replace <instance> with the name or ID of the instance to migrate. A status of "ACTIVE" indicates that the instance is ready to use.

   • If the migration did not work as expected, revert it:

      $ openstack server resize --revert <instance>

     Replace <instance> with the name or ID of the instance.

5. Restart the instance:

    $ openstack server start <instance>

   Replace <instance> with the name or ID of the instance.

6. Optional: If you disabled the source Compute node for maintenance, you must re-enable the node so that new instances can be assigned to it:

    $ openstack compute service set <source> nova-compute --enable

   Replace <source> with the hostname of the source Compute node.

7. Exit the OpenStackClient pod:

   $ exit

Procedure

1. Access the remote shell for the OpenStackClient pod from your workstation:

   $ oc rsh -n openstack openstackclient

2. To live migrate an instance, specify the instance and the destination Compute node:

    $ openstack server migrate <instance> --live-migration [--host <dest>] --wait

   • Replace <instance> with the name or ID of the instance.

   • Replace <dest> with the name or ID of the destination Compute node.

     Note

     The openstack server migrate command covers migrating instances with shared storage, which is the default. Specify the --block-migration flag to migrate a locally stored volume:

      $ openstack server migrate <instance> --live-migration [--host <dest>] --wait --block-migration

3. Confirm that the instance is migrating:

    $ openstack server show <instance>
   
   +----------------------+--------------------------------------+
   | Field                | Value                                |
   +----------------------+--------------------------------------+
   | ...                  | ...                                  |
   | status               | MIGRATING                            |
   | ...                  | ...                                  |
   +----------------------+--------------------------------------+

4. Wait for migration to complete. While you wait for the instance migration to complete, you can check the migration status. For more information, see Checking migration status.

5. Check the status of the instance to confirm if the migration was successful:

    $ openstack server list --host <dest> --all-projects

   Replace <dest> with the name or ID of the destination Compute node.

6. Optional: If you disabled the source Compute node for maintenance, you must re-enable the node so that new instances can be assigned to it:

    $ openstack compute service set <source> nova-compute --enable

   Replace <source> with the host name of the source Compute node.

7. Exit the OpenStackClient pod:

   $ exit

Procedure

1. Create or update the ConfigMap CR named nova-extra-config and set the value of [libvirt] live_migration_parallel_connections to a value greater than 1, for example 4, and set [libvirt]live_migration_permit_post_copy to false:

   apiVersion: v1
   kind: ConfigMap
   Metadata:
       name: nova-extra-config
       namespace: openstack
   data:
       42-nova-parallel-connections.conf: |
         [notifications]
         live_migration_parallel_connections = 4
         live_migration_permit_post_copy = false

   For more information about creating ConfigMap objects, see Creating and using config maps in Nodes.

2. Create a new OpenStackDataPlaneDeployment CR to configure the services on the data plane nodes and deploy the data plane, and save it to a file named compute-parallel-connections_deploy.yaml on your workstation:

   apiVersion: dataplane.openstack.org/v1beta1
   kind: OpenStackDataPlaneDeployment
   metadata:
     name: compute-parallel-connections

   For more information about creating an OpenStackDataPlaneDeployment CR, see Deploying the data plane in Deploying Red Hat OpenStack Services on OpenShift.

3. In the compute-parallel-connections_deploy.yaml, specify nodeSets to include all the OpenStackDataPlaneNodeSet CRs you want to deploy. Ensure that you include the OpenStackDataPlaneNodeSet CR that you selected as a prerequisite. That OpenStackDataPlaneNodeSet CR defines the nodes you want to designate for parallel connections.

   Warning

   If your deployment has more than one node set, changes to the nova-extra-config.yaml ConfigMap might directly affect more than one node set, depending on how the node sets and the DataPlaneServices are configured. To check if a node set uses the nova-extra-config ConfigMap and therefore will be affected by the reconfiguration, complete the following steps:

   1. Check the services list of the node set and find the name of the DataPlaneService that points to nova.

   2. Ensure that the value of the edpmServiceType field of the DataPlaneService is set to nova.

      If the dataSources list of the DataPlaneService contains a configMapRef named nova-extra-config, then this node set uses this ConfigMap and therefore will be affected by the configuration changes in this ConfigMap. If some of the node sets that are affected should not be reconfigured, you must create a new DataPlaneService pointing to a separate ConfigMap for these node sets.

   apiVersion: dataplane.openstack.org/v1beta1
   kind: OpenStackDataPlaneDeployment
   metadata:
     name: compute-parallel-connections
   spec:
     nodeSets:
       - openstack-edpm
       - compute-parallel-connections
       - ...
       - <nodeSet_name>

   • Replace <nodeSet_name> with the names of the OpenStackDataPlaneNodeSet CRs that you want to include in your data plane deployment.
4. Save the compute-parallel-connections_deploy.yaml deployment file.

5. Deploy the data plane:

   $ oc create -f compute-parallel-connections_deploy.yaml

6. Verify that the data plane is deployed:

   $ oc get openstackdataplanenodeset
   NAME           STATUS MESSAGE
   compute-parallel-connections True   Deployed

7. Access the remote shell for openstackclient and verify that the deployed Compute nodes are visible on the control plane:

   $ oc rsh -n openstack openstackclient
   $ openstack resource provider list

1. Queued: The Compute service has accepted the request to migrate an instance, and migration is pending.
2. Preparing: The Compute service is preparing to migrate the instance.
3. Running: The Compute service is migrating the instance.
4. Post-migrating: The Compute service has built the instance on the destination Compute node and is releasing resources on the source Compute node.
5. Completed: The Compute service has completed migrating the instance and finished releasing resources on the source Compute node.

Procedure

1. Access the remote shell for the OpenStackClient pod from your workstation:

   $ oc rsh -n openstack openstackclient

2. Retrieve the list of migration IDs for the instance:

   $ openstack server migration list --server <instance>
   +----+-------------+-----------  (...)
   | Id | Source Node | Dest Node | (...)
   +----+-------------+-----------+ (...)
   | 2  | -           | -         | (...)
   +----+-------------+-----------+ (...)

   Replace <instance> with the name or ID of the instance.

3. Show the status of the migration:

   $ openstack server migration show <instance> <migration_id>

   • Replace <instance> with the name or ID of the instance.

   • Replace <migration_id> with the ID of the migration.

     Running the openstack server migration show command returns the following example output:

     +------------------------+--------------------------------------+
     | Property               | Value                                |
     +------------------------+--------------------------------------+
     | created_at             | 2017-03-08T02:53:06.000000           |
     | dest_compute           | controller                           |
     | dest_host              | -                                    |
     | dest_node              | -                                    |
     | disk_processed_bytes   | 0                                    |
     | disk_remaining_bytes   | 0                                    |
     | disk_total_bytes       | 0                                    |
     | id                     | 2                                    |
     | memory_processed_bytes | 65502513                             |
     | memory_remaining_bytes | 786427904                            |
     | memory_total_bytes     | 1091379200                           |
     | server_uuid            | d1df1b5a-70c4-4fed-98b7-423362f2c47c |
     | source_compute         | compute2                             |
     | source_node            | -                                    |
     | status                 | running                              |
     | updated_at             | 2017-03-08T02:53:47.000000           |
     +------------------------+--------------------------------------+

     Tip

     The Compute service measures progress of the migration by the number of remaining memory bytes to copy. If this number does not decrease over time, the migration might be unable to complete, and the Compute service might abort it.

4. Exit the OpenStackClient pod:

   $ exit

   Sometimes instance migration can take a long time or encounter errors. For more information, see Troubleshooting migration.