That is only RAID 1 or mirrored. There is also RAID 0 which is \"striped\" or using 2 drives in parallel. Each one feeds 1/2 of the data to the processor. It does not work out to be twice as fast as a single drive due to \"overhead\" but somewhere on the order of maybe 70% faster. So two 40 gig 7,200 rpm drives are faster and lots cheaper than one 80 gig 10,000 rpm drive using RAID 0. IDE RAID can be set up for RAID 0 or 1 if you have 2 drives of the same size.