Problem
Hosts often need to be brought down for maintenance and having instances scheduled to those hosts can disrupt workloads at such times. Hence the option to enable Maintenance Mode on a host.
This option disables the nova-compute service so that no new resources are created on the host.
Environment
- Platform9 Managed OpenStack - All Versions
- Nova
- OpenStack CLI
- Clarity UI
Procedure
- Log in to the Clarity UI as an Admin user.
- Select the Host -> Toggle Maintenance Mode
Note: Enabling Maintenance Mode will prevent additional Instances from being created on the Host. All Instances running on the Host should be removed prior to performing maintenance. If there are instances on the host after enabling maintenance mode those will need to be moved to another host using nova-evacuate. - Use the OpenStack CLI to verify if the compute service on the host is disabled.
$ openstack compute service list | grep <host_uuid>
Example:nova-compute | 394cb179-543e-4e20-979c-b6bf0a6bc4d1 | nova | disabled | up |