You can setup just Raid 0 or just Raid 1 with minmum of two hard drives but it'll take four hard drives to setup both Raid 10. Raid 0+1 is doing disk striping, Raid 0 writes data across two disk drives to improve disk performance and also at the same time doing disk mirroring, Raid 1 data written to one disk drive is simultaneously written to another disk drive. If one hard drive fails, you can keep your pc running with the data stored on the other hard drive and to reconstruct the failed drive. Raid 1 is more suitable for pc servers.