The capacity bar has been raised according to TDK's roadmap.
A recent roadmap presented by TDK Corporation--a manufacturer of read/write heads for many hard disk drive (HDD) suppliers--revealed that 640 GB 2.5-inch and 2.5 TB 3.5-inch HDDs should become available around January 2010. For now, Seagate and WD provide HDDs with the largest capacities: 2 TB.
According to Register Hardware, TDK is currently producing high density read/write heads for 250 GB/platter (2.5-inch) and 500 GB/platter (3.5-inch). However, the roadmap indicates that the 2.5-inch drive read heads will jump up to 320 GB/platter (which apparently are already in qualification by its OEMs), and the 3.5-inch drive read heads will move up to 640 GB/platter.
The 3.5-inch 4-platter HDDs are expected to enter mass production in November and exit in January. The 2.5-inch 2-platter drives, on the other hand, will enter manufacturing this month and slip into mass production by December. HDD manufacturers should begin announcing the 2.5-inch drives by the end of the year, and the 3.5-inch drives as early as February 2010.
3.5-inch manufacturers may even provide a possible 3.2 TB, 5-platter model next year.