What is the most important thing in administering a Linux (or any other) system?
Ken Hess listed 5 Things Every Good Linux Administrator Knows and left out the most important thing. It is more important than uptime. It is more important than controlling the network services. It is more important than making users happy. It is more important than documentation.
REGULAR BACKUPS!
UPDATE (2008 Nov 07):
A day after I wrote the above, Ken Hess added 3 More Things Every Good Linux Adminstrator Knows, the first of which is regular backups.
I agree. Backups are very important. Too many beginners don’t realise that, until they encounter a data loss, which teaches them a lesson for life.