Disparities in the capacities of notebooks hard drives are widening. Samsung and Western Digital have both begun to offer 250 GB notebook hard drives, for example. However, although Samsung told us that its SpinPoint M5S has been shipping for a couple of weeks, it is Western Digital's 250 GB Scorpio drive that arrived at our storage test lab first. And it's one hell of a hard drive.

With the exception of Fujitsu's MHV2200BT and the Toshiba MK2035GSS (both store 200 GB), the maximum storage capacity of 2.5" hard drive has been 160 GB. Fujitsu launched devices with a 200 GB capacity by creating a three-platter drive instead of single-platter or two-platter configurations. The height of the drive measured 12.5 mm, which prevented it from being used in almost all notebooks, because most notebook designs require 9.5 mm drives. Toshiba's 200 GB drive fits into standard 2.5" drive bays, but it rotates at the slow speed of 4,200 RPM. While this may be quick enough for applications such as external hard drives, mainstream demands now calls for notebook hard drives with speeds of 5,400 RPM. According to our tests and measurements, this speed currently represents the best compromise between performance, capacity and power consumption.

Compared to the maximum capacity for 5,400 RPM 2.5" drives, which has been 160 GB, 250 GB represents a 55% increase in storage capacity. This is much larger than usual capacity increases that typically are in the range of 10-30%. The increase in data density clearly can be attributed to perpendicular recording technology, which aligns the magnetizable elements on the platters in a vertical fashion (perpendicular) rather than magnetizing horizontally (longitudinal). PMR technology does not only allow much higher data densities by moving bits closer together, but it also improves data integrity by working against the superparamagnetic effect, which causes magnetic particles to influence each other.

We were in the middle of testing eight additional hard drives to add their test and benchmark results to our Interactive 2.5" Hard Disk Charts when the Western Digital Scorpio WD2500BEVS arrived at our test lab. The contenders from Fujitsu, Hitachi, Samsung and Toshiba all spin at 5,400 RPM and also utilize perpendicular magnetic recording technology (PMR), which results in a very representative test bed.

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