The merger of IBM's and Hitachi's hard drive businesses a couple of years ago has resulted in the first notebook hard drive designed by Hitachi that runs at 7,200 rpm. Seagate's Momentus, operating at 5,400 rpm, was designed to consume the same amount of power as 4,200 rpm drives. Both of the new 2.5" devices we tested will likely usher in a new era of smaller and faster hard drives that will meet a wide range of data-hungry, mobile applications.

The novelty of 2.5" hard drives lies in their versatility compared to their bulkier 3.5" predecessors. For small and compact electronic devices including notebooks, tablet PCs, auto, or satellite information systems; mass storage of the future must be small, light, and robust.

The development of smaller and more powerful drives is largely limited by how data transfer rates depend to a large extent on the rotation speed of the storage disks. The smaller the disk, the slower it will be in absolute terms-even when data densities continue to rise sharply. Hence, Hitachi's latest 1.8" microdrives will not match the data rates of larger modern desktop hard drives.

But at least one vendor has been able to meet the smaller and faster challenge, which Hitachi has accomplished with its 7,200 rpm, 2.5" drive.