Nearly every external USB drive we see now uses a USB 2.0 connection. And for good reason, since it's a good cross-platform solution to transfer data at reasonable speeds; it's hot swappable (so you don't need to restart your computer every time you plug in or disconnect); and it even provides power over the connection so that notebook drive-based external units don't need extra power supplies.

But as capacities increase, along with our appetite for more storage space, so the USB 2.0 connection is showing its age. Popular on the Mac side there is FireWire, in real terms usually faster even in its original ‘400' version than USB 2.0's nominal 480Mb/s transfer speed. And the FireWire 800 flavour is much faster again.

A new connection format for external drives is starting to emerge now which promises data transfer speeds closer to that available with SATA hard drives mounted inside a computer. Known as eSATA, we found this port included on the latest external drive case of the Akasa Integral P2NSX case, designed to carry 2.5in notebook drives.

The Akasa Integral P2NSX case is finished in a smart gloss finish - ours came in black - over an aluminium body, with chrome-effect plastic end caps. To fit a new drive you need only remove two screws on the back plate, slide out the circuit board assembly and slot in a 2.5in SATA drive. It's held in place by the snug fit of the main aluminium sleeve.

An additional port for 5V power is included, and you'll need to use either this or the included extra USB cable in order to power the Akasa Integral P2NSX when using eSATA as the current specification does not, unlike USB 2.0, allow bus power to spin up the hard disk.

We fitted it with a high-performance Toshiba 200GB SATA hard disk with 7200rpm spindle speed. Because of this hard disk's higher specification and hence greater power consumption, we also found it necessary to power the drive with the help of two USB cables instead of one.

When transferred data via USB 2.0, our HD Tach measurements showed an average read speed of 30.2MB/s and write of 23.7MB/s. The burst speed, an indication of the bottleneck of the connection type, was 34.0MB/s.

When using the eSATA connection method, these figure rose to 57.5MB/s read and 58.9MB/s write, with a burst capability of 139.3MB/s. That's a near doubling and tripling of read/write speeds, respectively, and an indication that burst speed actually exceeded 1.2Gb/s.

Interestingly, even with the higher speed eSATA connection, a figure of around 60MB/s for read and write speeds still only just meets the promised speed (‘480Mb/s') of USB 2.0. In practice, most USB 2.0 drives we've seen are closer to the speed of this Akasa case, in other words a 160-240Mb/s operational speed. But by using the eSATA link, usefuly higher speeds are now attainable for a portable external storage device, even if they fall short of the headline 3Gb/s speeds you may see in the marketing. Which means larger video files and picture and music libraries can now be exchanged that much more speedily.


The Akasa Integral P2NSX external enclosure is a nicely finished case for holding 2.5in notebook-type hard disk drives, with an eSATA connection option that can double the speed of reading data, and triple the speed when writing to the drive.