I am responsible for managing both our production server (mail, web, database are all on one server) and our test server. Both are built on Debian. However as I am very new to system administration, I have only been installing updates as I come across things that have to be updated so that I can have newer features and get bug fixes. Its a pretty ad hoc process right now, and I'd like to make it less so.
So I am wondering how people who know what they're doing handle this? How often do you perform upgrades on your servers? Is the upgrade process different between test and production? Do you always upgrade any test servers first? And do you do a full update of all software, or do you just install selected updates?