USB 2.0 external hard drives, in 3.5 inch ‘desktop' and smaller 2.5 inch ‘mobile' form, are ten-a-penny, and most of them cost remarkably little for the storage capacities they offer. Now a handful of desktop and portable drives with eSATA interfaces are starting to appear in synch with the slow adoption of the interface on laptops and some desktops.

Given that they cost more, are they worth the extra money? It should be pointed out that the USB 3.0 interface is expected to become more common within the next three years, the 5Gbit/s theoretical bandwidth will somewhat exceed eSATA's still impressive 3Gbit/s, so some people might be tempted to wait. To put this into perspective, USB 2.0 is limited to 480Mbit/s.

On the other hand, an boosted eSATA standard will likely also turn up one day on the basis that the internal SATA 3.0 standard is about to reach 6Gbit/s though that will need a new chipset at both ends of the connection.

LG's rather attractive (red, black and white with a nice patina) XD1 drives are among the very first 5,400rpm portable drives featuring an eSATA port to complement the standard USB 2.0 connector.

The drive manifests the pros and cons of the interface. Full marks to LG for supplying an eSATA cable in addition to the USB 2.0 cable, but it is thick and unwieldy in a way that would have been alien to mere PC users not long ago. It also requires a firm push to get it into the interface on the drive and the eSATA port on the PC at the other end, and we'd suspect that this is not a connector that would necessarily stand up to years of repeated connecting and disconnection. It feels more like a static desktop connector.

Unlike USB 2.0, the drive cannot be powered from a bus cable alone, and requires a separate cable that uses up a spare USB port, another drawback. That port would also have to be sited near the eSATA interface on the host machine, although the cable is long enough to stretch to the back of the laptop on which we tested it.

The only physical issue with the drive was that it lacked feet or any kind of cushioning on its underside, which means the smooth plastic will tend to get scraped sitting on most surfaces. Despite its hard outer shell, LG does claim that the drive is shock resistant.
Other possible ‘gotchas' are limited to early eSATA chipsets that might (but probably won't) cause issues with a given drive.

How much faster is the LG XD1? That depends on a number of factors, as it does to some extent with any data transfer interface. The rotational speed of the hard drive matters, which in the case of the LG unit is the standard 2.5 inch speed of 5,400rpm; the desktop 3.5 inch version betters this with 7,200rpm and that might make a slight difference in everyday use. The other unknown is the chipset used on the eSATA card or built on to the laptop motherboard. That will make a difference too though probably a marginal one on any given OS/driver/file system combination.

Our tests showed that the drive is roughly twice as fast as an equivalent USB 2.0 drive, or itself through its own USB interface, transferring at an average data rate of 17.4MB/s compared to USB's 8.70MB/s for the same files. In both cases, that's a way down on the theoretical maximum, but it still demonstrates that eSATA is sprightly by today's standards. The drive's read speed when opening a sequence of files was about twice that if USB.

Conclusion
Anyone with a need to move or backup large numbers of files on the move, for instance image files or videos, will appreciate being able to do so faster than can be done with a standard USB drive. The latter, which seemed so fast and simple when it turned up a decade ago, is now inadequate for today's needs, and eSATA is a step in the right direction. Whether with USB 3.0 in the offing, it's a long-term in investment is another matter.

On balance, it's probably worth the modest added cost - around 25 percent or so - as long as shifting bits as fast as possible is a priority.

OUR VERDICT

Users lacking the eSATA interface can easily fit one either in card form (around £20 for an internal card and not much more for a laptop PC Card), and get the extra performance offered by eSATA. With USB 3.0 coming along, it's harder to say that it's a long-term investment, and might turn out to be more of a mezzanine technology that fills a need until something better and more widely-found comes along.