Western Digital Caviar Green 3TB review

Mechanical hard disks are looking unfashionable these days as solid-state storage filters into the mainstream. But they’re still much cheaper and can offer vastly greater storage capacities, as Western Digital’s monster 3TB disk – the largest we’ve seen to date – demonstrates.

The Caviar Green range focuses on quietness and low power consumption, rather than maximum performance, but this drive’s quoted idle draw of 5.5W is surprisingly high; the 2TB model is listed as just 2.5W. Still, it’s no worse than average for a desktop drive, and lower than the 6.3W rating of the A-Listed Samsung Spinpoint F3. The drive proved quiet in operation too, spinning with a gentle whirr but none of the chattering you get from some units.

While speed isn’t a major selling point, the drive still completed our file-copying tests in good time. In our large file tests it averaged read and write speeds of 110MB/sec and 169MB/sec; some way off the Samsung’s scores of 138MB/sec and 208MB/sec, but still fast enough for general-purpose use.

The best news came in the small-file exercises. Last year’s Caviar Green drives performed dreadfully in our Labs tests, taking ten times as long to write data as their rivals. But the 3TB Caviar Green gave a strong performance. It read our 15,000 files at an average rate of 73MB/sec, about on a par with other green drives, and wrote them back at a remarkable 71MB/sec – faster even than Western Digital’s flagship 2TB Caviar Black, which managed 50MB/sec in the same test.

Doubtless that’s partly thanks to the Caviar Green’s generous 64MB cache, but it’s also a thumbs up for Western Digital’s “advanced format”, which improves efficiency by storing data in 4KB clusters rather than the 512-byte clusters used by older drives. We suspect it was teething troubles with this format that crippled last year’s drives, but evidently it’s working perfectly now.

There is still one catch, however. Windows can’t boot from a disk larger than 2.19TB unless you have a UEFI motherboard and a 64-bit OS — and Windows XP doesn’t support drives of this size at all. For most users, the 3TB Caviar Green will therefore be usable only as secondary storage, and you may also have to connect it via the bundled PCI-E x1 SATA controller if your motherboard doesn’t recognise the full capacity.

Top-of-the-range hardware is never cheap, either: at £162 exc VAT, the 3TB Caviar Green costs a lot more than you’d pay for two 1.5TB units (now selling online for around £47 each). At 5.8p/GB it’s the sort of price you’d associate with a high-performance workstation drive rather than a green model.

Still, with our favourite SSD – the Kingston SSDNow 100V – coming in at £1.48/GB for a 128GB model, the 3TB Caviar Green doesn’t look bad. It’s a shame that most of us won’t be able to use it as a system drive, but it’s still undeniably convenient to get this much storage with decent performance in a single unit and, as the price falls, that appeal will only grow.

This review was updated on 30 November to make clear that there is limited hardware and software support for drives of this size.