# oslevel 18.104.22.168
smitty it say's it needs a reboot, but I don't want to reboot. How can I change the TimeZone to UTC without rebooting?
You can change the timezone with smitty, the reason it wants a reboot is because services like cron are running with the old settings.
In order to avoid the reboot you would need to,
If you don't care that services are running with the wrong timezone, then you don't need to reboot the server.
As a minimum, to avoid rebooting you should kill cron and let init restart it. Other services may or may not need restarting depending on your preference and what logs you don't mind being wrong.
Google is your friend. From here: