It is possible to move an instance from one compute host to another in OpenStack. This is a common task when compute node has issues or maintenance has to be done on it. The openstack server migrate command is used to migrate an openstack instance from one compute host to another.
The Nova scheduler will automatically choose the destination compute host based on its settings. The migration process does not assume instance has shared storage available on the target host. For those using SSH tunneling, ensure that each node is configured with SSH key authentication so that the Compute service can use SSH to move disks to other nodes.
You can do a Live migration or Non-live migration. In Non-live migration, the instance is shut down, then moved to another hypervisor and restarted. The instance recognizes that it was rebooted, and the application running on the instance is disrupted.