Good advice. Raid 1+0 (stripes of individual mirrors) is the most expensive (100% hardware redundancy required) but by far the highest performance. Raid 5 is roughly 3 to 1 times slower in write speed and about the same in read speed. If you lose a hard disk in RAID 5, all performance bets are off. Reconstruction / rebuild after replacing a failed 200 GB disk can take DAYS to complete for a RAID 5 system. This still beats having to reload / rebuild hundreds of GigaBytes of data. Software RAID is very slow compared to hardware solutions (roughly 10 to 1 penalty in my experiance) and uses a LOT of native CPU cycles. It's cheap but don't expect spectacular performance.