I'm interested in picking up a Glyph GT 062 Hard Drive but I can't figure one thing out. Since it supports RAID 0 and 1 is it actually the size its shown to be or is it half of that? For example if I got a 500gb one, would it actually be 250gb? If you've used one of these drives and have experience with them let me know. http://www.guitarcenter.com/Glyph-GT-062-FireWire-USB-2-0-External-Drive-241803-i1387275.gc Thanks!