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.

Zerto Virtual Replication enables moving recovery disks managed by a VRA on a host that needs maintaining to be moved to another host for the duration of the maintenance, as described in “Managing Protection During VMware Host Maintenance”, on page 306.