There’s been a lot of talk about Green Computing over the last few years, and the hard disk drive has not been exempt from this discussion. A number of vendors have announced the release of ‘green’ hard drives. Let’s take a look at some of the things that make a hard disk green and see how these ‘green’ disk drives are designed to meet these goals.
Low Power Consumption
Lower power consumption is perhaps the main characteristic that disk manufacturers are using to claim ‘green’ status. The claim is that a ‘green’ hard disk drive uses less power than one that isn’t ‘green.’ There are various methods to reach this lower power consumption goal. One such method is to lower the hard drive’s spindle speed – a drive running at 5400 RPM, for example, uses less electricity than one running at 10,000 RPM. Slower spindle speed can be used in green hard disk drives to help lower their power consumption. Some drive manufacturers have taken this a step further by having HDD controllers that adjust the speed, depending upon the required data transfers.
Power requirements of ‘green’ drives are also reduced by reducing the number of platters that are used by the drive. Take, for example, a 1 TB drive. A standard drive may use four platters, with 250 GB capacity per platter. A ‘green’ drive, by contrast may use only three platters, each platter being 333 GB in capacity. The energy saved by not having to rotate a fourth platter can help to make a drive ‘green.’
Another technique that may help to reduce the energy consumption in a green drive is so-called ‘intelligent’ head movement. Although we’re probably talking microseconds, the heads in a green drive might be moved slightly less quickly to meet up with the desired location on the rotating platter. In this case, because the platter IS always moving, rushing the head to a spot under the platter where it has to wait for the platter to line up uses more energy than more slowly moving the head over (or under) the platter. These little savings can add up enough to make a hard drive more energy efficient than its standard counterparts.
Another technology advance, seen in recent hard drives (both green and non-green), is the use of larger data sectors. Because the drive head can transfer more data to or from each sector, there is less repositioning of the head than was required by previous drives with smaller sectors. With less head positioning and repositioning required, energy consumption in drives with the larger sectors can be reduced.
In the next part of this blog, we’ll look at more factors that make a ‘green’ drive ‘green,’ and look at the question of whether a ‘green’ drive can provide adequate performance.