PC Perspective posted a review on the Western Digital RE RAID Edition 4TB SATA Enterprise Drive
The Western Digital RAID Edition line of hard drives has been around for some time now, and has largely impressed us with each subsequent release. Since the launches of the RE4-GP and later, the faster spinning RE4, WD's enterprise line had been capped at the 2TB mark. Now that has changed with the introduction of a new line: simply named the RE Series:Western Digital RE RAID Edition 4TB SATA Enterprise Drive - Full Review
Yup, that's right. 4 TeraBytes! With the Green and Red series capped at 3TB, this new RE is the largest capacity drive available from Western Digital. The catch is that, since it's tailored and built for enterprise use, it comes at a rather hefty price premium.