External hard disk buying guide

Posted on 14 Dec 2009 at 15:08

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Find out all you need to know about choosing the right external hard disk.

Recommended minimum specifications

Size: Desktop

Capacity: 500GB

Spindle speed: 7,200rpm

Interface: USB

Follow the steps to choose your ideal specs

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A basic external hard disk for simple backups designed to sit on your desktop with the specifications shown above will cost around £65. Smaller capacity disks may be cheaper, but won't be as good value due to the higher cost per gigabyte.

If you need more capacity, it's best to buy the largest hard disk you can afford. If you're using your external hard disk to back up your internal disk, the general rule is to buy an external disk with twice the capacity so you have enough room for other files.

If you transport lots of files, you'll need a portable hard disk. Those using a 2½in hard disk (as used in laptop PCs) are the best value and are available in capacities up to 500GB. They're small enough to slip into a coat pocket or a bag. However, they're more expensive than desktop versions. If size is really important, you need a pocket drive. An external drive that uses a 1.8in hard disk (iPod-sized) is a good bet. These tend to have a maximum capacity of 120GB.

Performance can be a big issue with 2½in drives. If you are writing a lot of data to and from a disk, choose one with a high spindle speed, as you'll get faster throughputs. Most pocket-sized hard disks have a spindle speed of 3,600rpm, while most 2½in hard disks spin at 4,200rpm or 5,400rpm. Desktop hard disks have a spindle speed of 7,200rpm.

USB is the most common interface found on external hard disks, and is also backwards-compatible with the slower USB 1.1. This is fast enough for most uses, but if you deal with very large files such as DV movies on a regular basis, a FireWire 400 hard disk will be quicker. FireWire 800 is faster, but few hard disks and fewer PCs have FireWire 800 ports. Meanwhile, eSATA hard disks can be even faster, but unless you have a very recent PC you will need to add eSATA ports to your computer using an expansion card. Every eSATA disk that you add requires its own port.

Author: Expert Reviews Staff

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