Western Digital put out one of the largest capacity dual-disk external drives on Thursday by introducing a 6TB version of the My Book Studio Edition II. The drive pairs two of the still-rare 3TB drives, optionally in a RAID mirror or stripe, and is aimed primarily at creative pros who deal with very large photos or videos on a regular basis. It comes pre-formatted for Macs; it can be reformatted for Windows, but it needs at least Vista or 7 to see more than 2.1TB.