Well, the reason is so I didn't have to buy another piece of gear. warwickt I think explained it well and I do plan to get an eSATA box to hold four drives. I'll probably buy two drives new drives, thinking Seagate es-2 1TB drives, and put two of my external drives in there, and leave one external 1 TB drive as a backup/floater. I'm waiting to see if I can cancel my order on 3 additional 1.5 TB drives for this new overall solution. ThanksIf I understood you right, you are going to be connecting 4 individual eSATA units. Why not use a single enclosure that holds 4 drives? If that's the case, you really should consider a single enclosure that holds 4 or more drives. As opposed to using 4 individually contained, individually powered drives. That's just not a good way to go about doing a reliable RAID setup.