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Hard disk roundup: every category tested
How we test
Although we’ve divided our drives into three broad categories, each unit, regardless of category, is subjected to an identical series of tests and calculations to identify its strengths and weaknesses. You’ll see the results summarised in the graphs on the following pages, along with tables detailing each drive’s physical characteristics and purchase information. We go into further technical detail in the main text as well.
Our first test involves measuring each drive’s performance. The speed at which a drive can read and write data is affected by a number of factors, including the size of its RAM buffer and the number of platters it uses. You’ll find details like this in the feature tables.
However, as our test results show, physical characteristics alone give only a very rough guide to performance. Therefore, we subject each drive this month to a battery of synthetic and real-world tests.
For our first test, we run our real-world application-based benchmarks on a standard system, using each disk as the system drive.
Then we use Simpli Software’s HD Tach application to measure each drive’s sequential, random access and burst read speeds, giving us the upper bound for each drive’s potential.
Finally, we combine the results – weighting our real-world benchmark results more heavily than the artificial measurements – to express each drive’s overall performance as a percentage of the average across all drives. This figure is given on the graphs on the coming pages.
We also measure each drive’s idle power consumption. Since Windows’ many background services cause constant fluctuations in the amount of power used, we measure total power consumption for a system sitting idle at the BIOS screen, then subtract the power draw observed with no drive attached. Even under these circumstances, power draw constantly wobbles up and down within a margin of one or two watts, and to counter that we take multiple readings over a 30-second period and record the average power draw with each drive.
Finally, we measure the noise generated by each disk. Each drive
is installed in a completely silent Home Server system. The system is then placed in a soundproof environment and precise acoustic measurements are taken, measuring the drive both when spinning idle and when read and writing data.
The tests are carried out by the independent testing centre Intertek.
We then weigh up all this in light of the drive’s value for money – not just its purchase price, but its cost in terms of cents per gigabyte of storage. Remember, though, that the hard disk market is a fast-moving one, so this calculation of value won’t hold forever.
Having taken all these factors into account, we award each drive a star rating out of six, indicating which models make for a great buy and which are better avoided.
Ratings explained
The star ratings you’ll find within each feature table are relative only to the products on test in any particular Labs. A one out of six rating doesn’t mean the product is the worst of its type to be made, just the least impressive that month. Likewise, a six out of six score isn’t necessarily an indication of perfection.
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