The 1 TByte 2.5" HDD: Once Again, Western Digital Leads On Capacity

Back in early April, I pointed out that Western Digital had in late January won the race to be the first vendor to ship a 2 TByte 3.5" HDD, by virtue of squeezing four 500 MByte platters into the form factor. This approach was reminiscent of the four-platter approach by which Hitachi got to the 1 TByte threshold first, in early 2007 (the company migrated to a more svelte 3-platter configuration 1.5 years later). And as far as know, six months later WD is still the only company shipping a 2 TByte 3.5" HDD.

Yesterday, WD crossed another notable finish line in the lead, this time being the first to shoehorn 1 TByte into a 2.5" HDD. The MSRP for the 1 TByte WD Scorpio Blue HDD (WD10TEVT), with 3 Gbps SATA interface and 8 MByte RAM cache, is $249.99; a 750 GByte version (the WD7500KEVT) is $189.99. External USB-interface variants are also available; MSRP on the 1 TByte My Passport Essential SE is $299.99 and the 750 GByte model is $199.99. Note the atypical 5200 RPM rotational speed on these drives versus the more common 5,400 RPM metric; I’m not sure if this was done to squeeze additional storage potential onto each platter, to enhance the drives’ power consumption capabilities, or for a combination of these (and/or other) reasons.

And speaking of platters, I should note that as before, WD accomplished its 1 TByte achievement by bumping the total per-drive platter count to 3, versus the more typical 1- and 2-platter specifications. This augmentation increases drive height to 0.49 inches (12.5 mm), thereby making the drives unusable in some ultra-thin system designs which are reliant on the more usual 0.374 inch (9.5 mm) thickness measurement. And as such, it’s not clear to me how much (if any) per-platter areal density leadership WD has over competitors such as Seagate.

To wit, and thanks to Stephen Foskett’s blog, I was made aware while researching this piece that Seagate is now promoting (and shipping?) a 640 GByte 2.5" USB-interface external HDD (PDF). Presumably it’s based on as-yet unannounced two-platter, single-drive technology, translating to 320 GBytes per platter. Compare this data point to the 250 and 333 GBytes/platter specifications of WD’s latest offerings, and you can see how close the two companies are in this particular respect.