The email server profile is a demanding 8k test with a 50 percent read and 50 percent write distribution. This application is indicative of the performance in heavy write workloads.
The HGST Ultrastar He6 averages 206 IOPS at QD256, while the 7K4000 averages 221 IOPS.
The He6 averages 8.05 watts, much lower than the 9.35 watts from the 7K4000.
The He6 manages to slightly best the 7K4000's efficiency in our final test.