Lab

External hard disks

If you've been a computer user for any length of time, you'll know the agony of running out of hard disk space. We're all constantly acquiring and creating data, and no matter how assiduously you clear out old and unwanted files, sooner or later you inevitably reach that fell point where the disk is full and there's nothing left you can bear to delete.

The traditional, and most economical, solution is to fit a larger hard disk, either as a secondary drive or to replace the over-stuffed original. These days, though, an external drive has become a realistic alternative.

Once, such devices commanded a considerable price premium compared with a bare drive, but times have changed. The PC has become a hub for music and video, not to mention ever larger digital photos and increasingly sizeable games. There's now a huge mainstream demand for a simple way of adding extra storage to a PC. At the same time, notebooks have surged in popularity, bolstering the market for external devices. And so sales of drives have increased, economies of scale have kicked in, competition has ramped up, and the price gap between external and internal drives has shrunk considerably.

So even if you hadn't previously considered an external device as a way of adding storage, it's worth doing so now. The benefit isn't just the ease of connecting the drive, although that isn't to be underestimated. Another attraction is portability. Even the bulkiest desktop drive can be easily tossed in a rucksack, and with a smaller model you can carry a quarter of a terabyte in your jacket pocket. With desktop drives increasingly offering eSATA, there needn't even be a trade-off in transfer speed compared to an internal drive - turn to p110 for a look at how the different connections compare.

This month, we put 13 current models to the test. Read on for our findings, and everything else you need to know to help you choose the right external drive.