In Spectrum Protect v7.1.3 an additional method to place the server in maintenance mode was introduced. In the documentation maintenance mode is described as “….the preferred method for starting the server before you begin maintenance or reconfiguration tasks”. Actions like verifying a server upgrade or a restored server database comes to mind. During maintenance mode, operations that might disrupt maintenance or reconfiguration tasks are automatically disabled. Basically all tasks that are related to the adjustment and movement of data. These are:
Administrative schedules Client schedules Reclamation Expiration Migration Client sessions are actively refused
During maintenance mode, the manual start of reclamation, expiration and migration is allowed.
The DSMSERV utility is now extended and placing a server in maintenance mode is now as simple as issuing: DSMSERV MAINTENANCE

Check for the output of ANR3415I:

This is the corresponding help text:

A piece of history for the old timers:
In the past maintenance mode was called starting the server in “Stand-alone” (sometimes “Single-user”) mode. But that list also included disabling all administrative sessions. The above list can be translated to:
Description | Option or command | Remark |
Disable administrative and client schedules |
DISABLESCheds Yes |
Translates to: ANR2718W Schedule manager disabled |
Reclamation and migration |
NOMIGRRECL |
|
Expiration |
EXPINterval 0 |
|
Administrative and client sessions are actively refused |
DISAble SESSions CLIent |
|
The only noticeable difference is that in the new, out of the box, maintenance mode it is not purely stand-alone as other administrators then yourself are allowed to connect to the Spectrum Protect server. But that can be easily fixed with the “disable sessions all” command.
To place a server in stand-alone mode: halt the server, place NOMIGRRECL, DISABLESCHEDS YES and EXPINTERVAL in dsmserv.opt, start the server and type “disable sessions all” as soon as it is available.
The return to normal mode: halt the server, remove the options from dsmserv.opt, start the server and type “enable sessions all”.
This was the procedure for many years, but now there is the convenient DSMSERV MAINTENANCE option. Explore it and update all your DR procedures 
For an IBM Training demo of this, check this YouTube video:
—- Tommy Hueber
Original author: tommy