Western Digital packs 1 Tbyte into 2.5-in. disk
By Brian Dipert, Senior Technical Editor -- EDN, August 20, 2009
Western Digital recently broke its own record, becoming the first to shoehorn 1 Tbyte into a 2.5-in.hard-disk drive. This breakthrough comes on the heels of the company’s becoming, in January, the first to ship a 2-Tbyte, 3.5-in. drive by squeezing four 500-Mbyte platters into the form factor. This approach was reminiscent of Hitachi’s four-platter approach, landing that vendor in first place to cross the threshold for 1-Tbyte, 3.5-in. hard-disk-drive storage in early 2007. The company migrated to a three-platter configuration 18 months later.
Western Digital’s drive, the WD Scorpio Blue, has a 3-Gbps SATA (serial-advanced-technology-attachment) interface and an 8-Mbyte RAM cache. The MSRP (manufacturer’s suggested retail price) is $249.99; a 750-Gbyte version, the WD7500KEVT, sells for $189.99. External USB (Universal Serial Bus)-interface variants are also available. MSRPs for the 1-Tbyte and 750-Gbyte versions of the My Passport Essential SE are $299.99 and $199.99, respectively. All these drives feature an atypical 5200-rpm speedversus the more common 5400 rpm—whether for additional per-platter storage potential, to enhance the drives’ power-consumption capabilities, or for other reasons.
Speaking of platters, the company accomplished its achievement by bumping the total per-drive platter count to three versus the more typical one- and two-platter specifications. This augmentation increases drive height to 0.49 in. (12.5 mm), thereby making the drives unusable in some ultrathin-system designs, which rely on the more usual 0.374-in. (9.5-mm) thickness. As such, it’s unclear how much if any per-platter areal-density leadership Western Digital has over competitors, such as Seagate.
Seagate is now promoting a 640-Gbyte, 2.5-in. hard-disk drive with an external USB interface. Presumably, the company based the product on as-yet-unannounced, two-platter, single-drive technology, translating to 320 Gbytes per platter. Compare this data point to the 250- and 333-Gbyte/platter specifications of Western Digital’s latest offerings, and you can see how close the two companies are in this respect.
This article originally appeared as an entry in the Brian's Brain blog. To view that article, please click here.
