How to properly shut down your AS/400
It is strongly recommended to properly shut down the machine if you need to power it off for any reason. If you just pull the plug, objects may get damaged. At least, the next IPL will take a lot more time.
If in an emergency, you may press the white power-on button twice to signal the machine a fast-power-off, that should happen in some ten seconds. That's not as harsh as pulling the plug but also not recommended, as the next IPL will also take longer than usual.
To properly shut down the machine ASAP, you need to be signed on as QSECOFR. Shutdown can be achieved with the Power-Menu:
and select the appropriate menu number for shutdown. Or you may also type
to signal the machine to end all jobs and do a proper system shutdown without waiting for other users to save data and end their sessions.
No matter which way you take, don't power off your twinax terminal yet, nor should you close your tn5250 session as long as the white status line text on the bottom of the display indicates that shutdown is in progress. If the twinax terminal only shows a blinking cursor and/or the tn5250 session(s) have been closed by the AS/400, it's safe to power off the terminal and/or close the tn5250 application.
Power down will initiate a lot of disk activity and you'll be presented again with SRCs on the LCD for knowing what the machine's currently doing. Shutdown usually takes about 2..3 Minutes from sending the command to final automatic power off of the machine.