Chapter 17. Rebooting nodes You might need to reboot the nodes in the undercloud and overcloud. Use the following procedures to understand how to reboot different node types. If you reboot all nodes in one role, it is advisable to reboot each node individually. If you reboot all nodes in a role simultaneously, service downtime can occurduring the reboot operation. If you reboot all nodes in your OpenStack Platform environment, reboot the nodes in the following sequential order: Recommended node reboot order Reboot the undercloud node. Reboot Controller and other composable nodes. Reboot standalone Ceph MON nodes. Reboot Ceph Storage nodes. Reboot Compute nodes. 17.1. Rebooting the undercloud node Complete the following steps to reboot the undercloud node. Procedure Log in to the undercloud as the stack user. Reboot the undercloud: Wait until the node boots. 17.2. 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 Log in to the node that you want to reboot. Optional: If the node uses Pacemaker resources, stop the cluster: Reboot the node: Wait until the node boots. Check the services. For example: If the node uses Pacemaker services, check that the node has rejoined the cluster: If the node uses Systemd services, check that all services are enabled: If the node uses containerized services, check that all containers on the node are active: 17.3. Rebooting standalone Ceph MON nodes Complete the following steps to reboot standalone Ceph MON nodes. Procedure Log in to a Ceph MON node. Reboot the node: Wait until the node boots and rejoins the MON cluster. Repeat these steps for each MON node in the cluster. 17.4. Rebooting a Ceph Storage (OSD) cluster Complete the following steps to reboot a cluster of Ceph Storage (OSD) nodes. Procedure Log in to a Ceph MON or Controller node and disable Ceph Storage cluster rebalancing temporarily: Select the first Ceph Storage node that you want to reboot and log in to the node. Reboot the node: Wait until the node boots. Log in to the node and check the cluster status: Check that the pgmap reports all pgs as normal ( active+clean ). Log out of the node, reboot the node, and check its status. Repeat this process until you have rebooted all Ceph storage nodes. When complete, log into a Ceph MON or Controller node and re-enable cluster rebalancing: Perform a final status check to verify that the cluster reports HEALTH_OK : 17.5. Rebooting Compute nodes Complete the following steps to reboot Compute nodes. To ensure minimal downtime of instances in your Red Hat OpenStack Platform environment, this procedure also includes instructions about migrating instances from the Compute node that you want to reboot. This involves the following workflow: Decide whether to migrate instances to another Compute node before rebooting the node. 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. Prerequisites Before you reboot the Compute node, you must decide whether to migrate instances to another Compute node while the node is rebooting. If for some reason you cannot or do not want to migrate the instances, you can set the following core template parameters to control the state of the instances after the Compute node reboots: NovaResumeGuestsStateOnHostBoot Determines whether to return instances to the same state on the Compute node after reboot. When set to False , the instances will remain down and you must start them manually. Default value is: False NovaResumeGuestsShutdownTimeout Number of seconds to wait for an instance to shut down before rebooting. It is not recommended to set this value to 0 . Default value is: 300 NovaResumeGuestsShutdownTimeout Number of seconds to wait for an instance to shut down before rebooting. It is not recommended to set this value to 0 . Default value is: 300 For more information about overcloud parameters and their usage, see Overcloud Parameters . Procedure Log in to the undercloud as the stack user. List all Compute nodes and their UUIDs: Identify the UUID of the Compute node that you want to reboot. From the undercloud, select a Compute node. Disable the node: List all instances on the Compute node: If you decide not to migrate instances, skip to this step . If you decide to migrate the instances to another Compute node, use one of the following commands: Migrate the instance to a different host: Let nova-scheduler automatically select the target host: Live migrate all instances at once: Note The nova command might cause some deprecation warnings, which are safe to ignore. Wait until migration completes. Confirm that the migration was successful: Continue to migrate instances until none remain on the chosen Compute node. Log in to the Compute node and reboot the node: Wait until the node boots. Re-enable the Compute node: Check that the Compute node is enabled:

Commands:
sudo reboot
[heat-admin@overcloud-controller-0 ~]USD sudo pcs cluster stop
[heat-admin@overcloud-controller-0 ~]USD sudo reboot
[heat-admin@overcloud-controller-0 ~]USD sudo pcs status
[heat-admin@overcloud-controller-0 ~]USD sudo systemctl status
[heat-admin@overcloud-controller-0 ~]USD sudo podman ps
sudo reboot
sudo podman exec -it ceph-mon-controller-0 ceph osd set noout sudo podman exec -it ceph-mon-controller-0 ceph osd set norebalance
sudo reboot
sudo podman exec -it ceph-mon-controller-0 ceph status
sudo podman exec -it ceph-mon-controller-0 ceph osd unset noout sudo podman exec -it ceph-mon-controller-0 ceph osd unset norebalance
sudo podman exec -it ceph-mon-controller-0 ceph status
source ~/stackrc (undercloud) USD openstack server list --name compute
source ~/overcloudrc (overcloud) USD openstack compute service list (overcloud) USD openstack compute service set [hostname] nova-compute --disable
(overcloud) USD openstack server list --host [hostname] --all-projects
(overcloud) USD openstack server migrate [instance-id] --live [target-host]--wait
(overcloud) USD nova live-migration [instance-id]
nova host-evacuate-live [hostname]
(overcloud) USD openstack server list --host [hostname] --all-projects
[heat-admin@overcloud-compute-0 ~]USD sudo reboot
source ~/overcloudrc (overcloud) USD openstack compute service set [hostname] nova-compute --enable
(overcloud) USD openstack compute service list