Think two terabytes is already too much? Just stick around a few more months. Quoting a presentation from TDK's drive-head business, Reg Hardware says we could see drive makers announce 2.5TB desktop hard drives "as early as February."
In 3.5" hard drives, current read heads typically support densities of up to 500GB per platter. However, TDK's roadmap shows that heads with support for 640GB platters are already in qualification, with a ramp to mass production scheduled to start in November and finish in January 2010. Commercial products should follow soon after. If drive makers get ballsy, they could even use five platters to make drives with staggering 3.2TB capacities.
What about the mobile side of things? For 2.5" hard drives, TDK expects to start mass-producing heads compatible with 320GB platters later this month. The ramp should be complete in December.
Of course, we should note that WD has already introduced 2.5" Scorpio Blue drives with 333GB platters, presumably using heads made by one of TDK's competitors. WD even offers a version of the Scorpio Blue that uses three platters to reach a 1TB capacity (although that also involves going above the standard 9.5-mm thickness for 2.5" drives).