Hitachi Deskstar 7K4000 (HDS724040ALE640)
This is Hitachi's high-performance 7200 RPM 4 TB drive. It's also based on a five-platter design, but it includes 64 MB of cache, instead of 32.
Power consumption in performance-idle mode (which means the drive is still spinning) is rated at 6.9 W. That's 40% more than the Deskstar 5K4000. In exchange, however, rated transfer rates increase from 161 MB/s to 205 MB/s, representing at least a 24% increase. The effective net performance is 163 MB/s. Although this is a solid result, it cannot match Seagate's Barracuda at 194 MB/s.
The Seagate drive isn't designed for 24/7 availability though, and the 7K4000 is. In other words, this Hitachi disk is the fastest high-end hard drive for performance-oriented applications that require lots of throughput. As far as I/O performance is concerned, let's just say we'd recommend looking for SSDs instead of disk drives.