This disk drive is bigger than I wanted, but newer and it worked perfectly in the RAID volume, replacing the broken 320 GB disk that I removed. The computer recognized it and rebuilt (mirrored) the functional drive. Very happy that I got a new drive, vs the one I ordered. All the really old disk drives (like the one I originally wanted to buy)had problems-bad sectors etc, so I got the 1 Terabyte unit instead. Worked like a champ.