Server maintenance best practices. What do you do?

I recently had a 3TB Apple RAID set trash its disk directory out of the blue. The Xserve OS runs on a separate drive and has been humming along with not a hitch for the last three years. Threre have been the occasional planned reboots and OS patches. The RAID also had absolutely no warning indications that there were any problems and the logs looked just fine. Everyting is on a UPS and there have been zero unexpected reboots or crashes that would normally explain disk directory corruption on the level that I saw.

My question is, what is the best practice for preventing such things from happening? Do you perform some kind of regular maintenance on your servers and RAID volumes and if so, what and how often? I’m a bit freaked out about the other RAID’s that have so far been running trouble free. Everything was backed up and the backups are working fine but restoring 3TB’s of data isn’t exactly a fast process.