Suspending a host for maintenance

Often times a host needs to be taken offline to have memory replaced, an operating system upgraded, or other routine maintenance done. In order to ensure that running instances are not adversely affected, we use the openstack compute service set command.

Getting ready

In order to place a host into maintenance mode, you will need the following information:

• The openstack command-line utility

• The nova command-line utility

• An openrc file with admin credentials

• The name of the host

The host we will put into maintenance mode is as follows:

• Compute host: compute-03

How to do it…

To remove a hypervisor for maintenance, carry out the following steps:

1. First, we will list the available hosts:

   source ~/openrc
   openstack compute service list -c Binary -c Host -c Status -f table
   

   This will bring back an output like the following:

   

2. Next, we will disable the service called nova-compute for the compute host, so we will specify:

   openstack compute service set --disable compute-03 nova-compute...