Game Development Dictionary
To Use RAID 0 or 1 you need 2 hard drives (any normal IDE), and for 0+1 you need at least 4 drives, while for spanning you can have any number greater then 2.
RAID 1 impoves your proformence by turning your connected hard drives effectively into one large one, as well as sharing the work between them, which doubles the proformence of the drives.
RAID 0 creates and stores a on the fly copy of your first hard disk onto the seccond drive in case of failure.
RAID 0+1, you have a RAID 0 working which is backed up onto other drives which are running in RAID 1.
SPAN connects any number of drives >2 togethor so that they appear as one big drive, however it DOES NOT share work between them like RAID 0, so you don't get a proformence increase.