You place a host in maintenance mode when you need to service it, for example, to install more memory. A host enters or leaves maintenance mode only as the result of a user request.

Virtual machines that are running on a host entering maintenance mode need to be migrated to another host (either manually or automatically by DRS) or shut down. The host is in a state of Entering Maintenance Mode until all running virtual machines are powered down or migrated to different hosts. You cannot power on virtual machines or migrate virtual machines to a host entering maintenance mode.

When no more running virtual machines are on the host, the host’s icon changes to include under maintenance and the host’s Summary panel indicates the new state. While in maintenance mode, the host does not allow you to deploy or power on a virtual machine.

Note

DRS does not recommend (or perform, in fully automated mode) any virtual machine migrations off of a host entering maintenance or standby mode if the VMware HA failover level would be violated after the host enters the requested mode.