uptime asks: "I've got a friend that needs some help with his web server availability. On two separate occasions, his server has had a problem that caused it to be unavailable for a period of time. One was early on and was probably preventable, but this latest one was due to two drives failing simultaneously in a RAID5 array. As a web business moves from a small site to a fairly busy one, availability and reliability becomes not only more important, but more difficult to accomplish it seems. Hardware gets bigger, services get more expensive, and options seem to multiply. Where could one find material on recommended strategies for increasing server availability? Anything related to equipment, configurations, software, or techniques would be appreciated."