Chapter 12. Rebooting Nodes

You may need to reboot the nodes in the undercloud and overcloud. Use the following procedures to understand how to reboot different node types. Be aware of the following notes:

  • If rebooting all nodes in one role, it is advisable to reboot each node individually. If you reboot all nodes in a role simultaneously, you might encounter service downtime during the reboot operation.
  • If rebooting all nodes in your OpenStack Platform environment, reboot the nodes in the following sequential order:

Recommended Node Reboot Order

  1. Reboot the undercloud node
  2. Reboot Controller and other composable nodes
  3. Reboot standalone Ceph MON nodes
  4. Reboot Ceph Storage nodes
  5. Reboot Compute nodes

12.1. Rebooting the undercloud node

Complete the following steps to reboot the undercloud node.

Procedure

  1. Log into the undercloud as the stack user.
  2. Reboot the undercloud:

    $ sudo reboot
  3. Wait until the node boots.

12.2. Rebooting controller and composable nodes

Complete the following steps to reboot controller nodes and standalone nodes based on composable roles, excluding Compute nodes and Ceph Storage nodes.

Procedure

  1. Select a node to reboot. Log into the node and stop the cluster before rebooting:

    [heat-admin@overcloud-controller-0 ~]$ sudo pcs cluster stop
  2. Reboot the node:

    [heat-admin@overcloud-controller-0 ~]$ sudo reboot
  3. Wait until the node boots.
  4. Re-enable the cluster for the node:

    [heat-admin@overcloud-controller-0 ~]$ sudo pcs cluster start
  5. Log into the node and check the services:

    1. If the node uses Pacemaker services, check the node has rejoined the cluster:

      [heat-admin@overcloud-controller-0 ~]$ sudo pcs status
    2. If the node uses Systemd services, check all services are enabled:

      [heat-admin@overcloud-controller-0 ~]$ sudo systemctl status
    3. If the node uses containerized services, check all containers on the node are active:

      [heat-admin@overcloud-controller-0 ~]$ sudo docker ps

12.3. Rebooting standalone Ceph MON nodes

Procedure

  1. Log into a Ceph MON node.
  2. Reboot the node:

    $ sudo reboot
  3. Wait until the node boots and rejoins the MON cluster.

Repeat these steps for each MON node in the cluster.

12.4. Rebooting a Ceph Storage (OSD) cluster

Complete the following steps to reboot a cluster of Ceph Storage (OSD) nodes.

Procedure

  1. Log into a Ceph MON or Controller node and disable Ceph Storage cluster rebalancing temporarily:

    $ sudo ceph osd set noout
    $ sudo ceph osd set norebalance
  2. Select the first Ceph Storage node to reboot and log into the node.
  3. Reboot the node:

    $ sudo reboot
  4. Wait until the node boots.
  5. Log into the node and check the cluster status:

    $ sudo ceph -s

    Check the pgmap reports all pgs as normal (active+clean).

  6. Log out of the node, reboot the next node, and check its status. Repeat this process until you have rebooted all Ceph storage nodes.
  7. When complete, log into a Ceph MON or Controller node and enable cluster rebalancing again:

    $ sudo ceph osd unset noout
    $ sudo ceph osd unset norebalance
  8. Perform a final status check to verify the cluster reports HEALTH_OK:

    $ sudo ceph status

12.5. Rebooting compute nodes

Complete the following steps to reboot Compute nodes. To ensure minimal downtime of instances in your OpenStack Platform environment, this procedure also includes instructions about migrating instances from the Compute node you want to reboot. This involves the following workflow:

  • Select and disable the Compute node you want to reboot so that it does not provision new instances.
  • Migrate the instances to another Compute node.
  • Reboot the empty Compute node.
  • Enable the empty Compute node.

Procedure

  1. Log into the undercloud as the stack user.
  2. List all Compute nodes and their UUIDs:

    $ source ~/stackrc
    (undercloud) $ openstack server list --name compute

    Identify the UUID of the Compute node you want to reboot.

  3. From the undercloud, select a Compute Node. Disable the node:

    $ source ~/overcloudrc
    (overcloud) $ openstack compute service list
    (overcloud) $ openstack compute service set [hostname] nova-compute --disable
  4. List all instances on the Compute node:

    (overcloud) $ openstack server list --host [hostname] --all-projects
  5. Use one of the following commands to migrate your instances:

    1. Migrate the instance to a different host:

      (overcloud) $ openstack server migrate [instance-id] --live [target-host]--wait
    2. Let nova-scheduler automatically select the target host:

      (overcloud) $ nova live-migration [instance-id]
    3. Live migrate all instances at once:

      $ nova host-evacuate-live [hostname]
      Note

      The nova command might cause some deprecation warnings, which are safe to ignore.

  6. Wait until migration completes.
  7. Confirm the migration was successful:

    (overcloud) $ openstack server list --host [hostname] --all-projects
  8. Continue migrating instances until none remain on the chosen Compute Node.
  9. Log into the Compute Node. Reboot the node:

    [heat-admin@overcloud-compute-0 ~]$ sudo reboot
  10. Wait until the node boots.
  11. Enable the Compute Node again:

    $ source ~/overcloudrc
    (overcloud) $ openstack compute service set [hostname] nova-compute --enable
  12. Check whether the Compute node is enabled:

    (overcloud) $ openstack compute service list