Interesting point I haven't seen discussed directly before: System administration, which includes operator actions, system configuration, and system mainte

Interesting point I haven't seen discussed directly before: System administration, which includes operator actions, system configuration, and system maintenance was the main source of failures -- 42%. Software and hardware maintenance was the largest category. High availability systems allow users to add software and hardware and to do preventative maintenance while the system is operating. By and large, online maintenance works VERY well. It extends system availability by two orders of magnitude. I've usually seen the online vs offline maintenance tradeoff depicted as the availability benefits of online maintenance vs the massive development cost of a system that remains available despite operator error during maintenance -- but if you meet the much easier standard of fail-fast (human error causes the system to go down but doesn't corrupt the database) then online maintenance is still an overall win even if it's the primary cause of failures.