Before you begin, you will need to ensure that the following has been carried out:

• Create the necessary baselines. Read the Creating patch baselines and Creating Host upgrade baselines recipes for instructions. 
• DRS should be enabled on the cluster. Update Manager will attempt to place the host into maintenance mode. Maintenance mode relies on DRS to migrate VMs with other hosts.
• What happens to the VMs on the host being put into maintenance mode by Update Manager can be controlled by using the Remediation Settings. Read the Configuring Update Manager's Remediation Settings recipe for more information.