The Thunderbolt version of LaCie's Little Big Disk comes in three varieties. Two of them contain hard disks, but this one packs solid-state drives. There are two inside, pre-configured as a striped RAID array for a total capacity of 240GB.

Although that pales in comparison to the less costly hard disk models, the pairing of Thunderbolt with even faster storage is an exciting proposition. LaCie quotes read speeds up to 480MB/s, around 290MB/s faster than the hard disk versions, and write speeds up to 245MB/s, which, although less jaw-dropping, is still a respectable boost of 55MB/s.

Our tests revealed a pleasant surprise: LaCie's figures are too conservative. It achieved 502.7MB/s when reading such files, and 256.7MB/s when writing them. Speeds tailed off for small files under 1MB, but the low of 24.2MB/s is respectable for them.

However, the Little Big Disk is really aimed at apps that require the ability to sustain high speeds when handling large files such as high-spec video, and it shines at this.

The Little Big Disk boasts a second Thunderbolt port for daisy-chaining other devices. So, connecting it to a MacBook doesn't forfeit the ability to work more comfortably with a second display.

Thunderbolt can deliver 10W of power to a device, but the drive requires an external power supply. It adds roughly a third of the drive's volume again, which isn't much. It's more irritating to carry another bulky three-pronged UK plug.

The drive's metal body is sturdy. It weighs 650g, or just under half a 13-inch MacBook Air. The ridged sides are intended to dissipate heat, but it was only lukewarm after copying 100GB to the drive. The fan, though, emitted a noticeable high pitch about halfway through.

Don't forget to add the £35 cost of Apple's Thunderbolt cable, which isn't bundled. But if you need and can afford this sort of performance when away from your desk, that isn't going to hold you back. Nor should it.

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