For quite some time now, 4TB hard drives have been conspicuously absent from Western Digital's lineup. That changes today with the introduction of a new family of RE models aimed at the server crowd. These latest offerings are available with SATA or SAS interfaces, and they boast capacities up to 4TB.
WD reaches the 4TB mark using five 800GB platters. The platter count is notable because WD has traditionally stuck with four or fewer platters. Turns out the RE 4TB has the same number of platters as the Ultrastar 7K4000 4TB, a similarly enterprise-oriented drive sold by Hitachi Global Storage products, which is now owned by WD. Both drives also feature dual-stage actuators, a technology we saw first in Western Digital products.
SAS versions of the RE will be available in 1, 2, 3, and 4TB capacities. The Serial ATA line drops the terabyte model and has slightly lower sequential throughput ratings. You don't buy these puppies for speed, though. The RE line is all about maximizing capacity, particularly for rack-mounted servers and storage. Indeed, Dell will be using the RE 4TB in its PowerVault MD3 series.
Although they won't set any benchmark records, the new REs still feature 7,200-RPM spindle speeds. SATA models have 64MB of cache, while SAS flavors sport half that. The cache will be the only thing fast enough to exploit the 6Gbps transfer rates offered by the respective interfaces.
The RE drives should be shipping as you read this. WD is charging $229, $349, and $549 for 2, 3, and 4TB versions of the SATA variant, respectively. SAS will cost you an extra 20 bucks per drive, with the terabyte model slated to sell for $139. Those prices aren't cheap, but they're largely in-line with the cost of the Ultrastar 7K4000. Keep in mind these are enterprise-grade drives. They're subjected to additional validation testing, including a "extended burn-in test with thermal cycling." The REs also feature RAID-specific error recovery routines, and they're more tolerant of high-vibration environments like densely packed servers. WD kicks in a five-year warranty, too.