If you are using the service console and want to put the ESX server into maintenance mode, simple run the following commands:
Enter maintenance mode:
vimsh -n -e /hostsvc/maintenance_mode_enter
Exit maintenance mode:
vimsh -n -e /hostsvc/maintenance_mode_exit
How do you check whether you are in maintenance mode or not?
vimsh -n -e /hostsvc/runtimeinfo | grep inMaintenanceMode | awk ‘{print $3}’