Toshiba has announced a 2.5-inch hard drive with 100GB capacity, 50GB per platter.

Japanese HDD vendors are making the running at the moment with Fujitsu and Hitachi announcing ever higher capacities in the 3.5 inch sector.

Seagate has its Savvio 2.5 inch drive with either 37GB or 73GB capacity and a 10,000rpm spin speed. Its UltraSCSI, Fibre Channel and SAS interfaces marks it out as an enterprise drive. Seagate is forecasting a move from 3.5in enterprise drives to 2.5in, saying that this increases I/O density. A 1U server system with 2.5in drives can execute the workload of a 2U server system with 3.5in drives, even a 3U system.

Steve Pereira, MD of Hitach Global Storage Technologies in the UK, supports this view: "The 2.5in form factor will come to high end servers. It has power and performance density benefits." He envisages the arrival of 2.5in 10,000rpm SATA drives.

Toshiba's MK1031GAS is built for "portable PCs". It has an ATA interface and spins at 4,200rpm, definitely not enterprise class. The areal density is 80Gbit/sq inch, which Toshiba claims is an industry-leading density figure. For comparison, Hitachi GST's Deskstar 7K400 (400GB 3.5in PATA/SATA drive) has a 61.7Gbit/sq inch areal density.

Toshiba says it can hold around 400 hours of MPEG-4 motion pictures of near DVD quality. Nick Spittle, business development director for Toshiba Storage Device Division Europe, said: "We are looking to storage technologies to deliver the necessary capabilities to carry a wealth of information and entertainment on the move." The target device sectors are multi-media personal devices such as DVD players and digital cameras/camcorders, in-car systems and the larger format notebook computers using 2.5in drives. (Smaller notebooks use 1.8in units.) Previous models in Toshiba's 2.5in drive range are used in Toshiba and, for example, Dell notebooks.

To cope with the increased areal density the read/write head uses a new Femto slider, smaller and lighter and which flies even closer to the disk surface than previous generation Pico sliders.

We can expect other manufacturers to follow suit as they gain the ability to match Toshiba's areal density levels.