Some people might believe that hard drives only differ in their performance. As a matter of fact, performance is only one chapter of the hard disc story. In an attempt to make drives faster, one popular measure has been to increase the rotational speed. As a result of higher friction, the drives become hotter and also make more noise due to high rotational speeds. That issue might not be a problem for servers, but home and office computers ought to run cool and should avoid noise as much as possible.
Test Criteria - Performance
A fast hard drive has to provide both short access times and high data transfer rates. The rotation speed has a big influence on both numbers, as it can both increase the transfer speed and reduce access times, due to the read/write heads having to wait less time until the requested data comes past the heads.
In order to increase performance, all modern disc drives come with an UltraDMA/66 (or UltraATA-2) interface and an internal cache memory. All drives in this article come with 2 Megabytes, apart from Seagate's 20 GByte Barracuda ATA I (which is in the process of being replaced by the faster Barracuda ATA II), which can only make use of 512 KBytes. In spite of this one vanishing from the market, I decided to include it in this review, as it has been our reference hard disc for almost all tests in the last six months.
Test Criteria - Noise Level
Every time you enter an office you can hear if computers are present. It is the power supply fan and the hard drive which are mostly responsible for the noise you can hear. High quality power supplies come with a thermistor and automatically increase or decrease the fan's rotation speed depending on the temperature inside the power supply.
The first hard drives that were running at 7,200 rpm produced a high frequency wheeze, which most people describe as almost unbearable if you have to work at or near them. Today, this wheeze could be reduced to a minimum, so that drives running 7,200 rpm are not any louder than 5,400 rpm models.
Test Criteria - Bad Vibrations
Apart from the spindle motor and all interrelated drive motions causing noises, the resulting vibrations can pass onto the computer case as well. Depending on the quality of your case, one or even several parts will be affected by them. I think you can imagine that vibrant parts of sheet metal are quite nasty and will destroy any remaining concentration. It's quite difficult to find a scientific method to mark out a number, which represents for the vibration level, so I hope you can live with my personal evaluation for the time being.