3DVelocity would like to thank Fujitsu, and in particular Mike Bain of Byron PR, for their invaluable help and generosity in supplying this product for review.

The Technology :

Released around July last year (2000) the MPG3xxx range of drives were a big hit with system builders. The MPG3xxxAT range was aimed squarely at the mainstream sector, with solid performance and a 5400rpm spindle speed. The MPGxxxxAH flagship range however, which saw light in October of 2000, raised the bar with an increased 7200rpm spindle speed and a range of technologies that set them apart from the competition.

Fluid Dynamic Bearings (FDB) :

This is a feature that even now, most of you may not have heard of. Several HDD manufacturers are now marketing their drives on the strength of them using FDB technology, but Fujitsu were very much the pioneering force, and have in fact been using the technology for some time now, allowing them a distinct advantage in that they have seen the technology mature and have been able to actively develop and improve both its performance and its reliability.
The principle of the FDB could demand a complete article to itself, but the simplistic explanation is that rather than using steel bearings to mount the platters, the spindle actually runs in a reservoir of viscous oil. There are several advantages to this arrangement, but the biggest is the reduction of Non Repeatable Run-Out or NRRO. Again keeping it simple, what this means is that with a conventional ball bearing, over time you may find that the steel balls inside the bearing develop "flat spots" or gradually become oval. This introduces an element of wobble into the spindle and thus the platters, meaning the reading head may stray from its track when reading or writing. This wobble (run-out) would of course be tolerable if it happened at exactly the same rotational position every time, but because of the nature of bearings this would never happen, and the wobble could happen just about anywhere (thus it becomes non repeatable). The upshot of this is that over time, data would be far more likely to become corrupt, or would at least take a lot longer to read.
Other advantages to the FDB are heat, noise, longevity and impact resistance. A 7200 rpm drive spindle running in oils will obviously stay cooler than when subject to the friction of a metal/metal contact. Also, because there is no metal/metal contact, there is no wear, meaning that (in theory at least) the lifetime of a fluid bearing is infinite. Again, the lack of any bearing surfaces means noise levels are drastically reduced, and as is the principle with the automotive shock absorber, knocks are absorbed by the viscous oil before they become transmitted to the platters and heads.

Giant Magneto-Resistive (GMR) heads :

Now here's another technology that could demand a review all to itself. Fujitsu was actually the first company to offer GMR technology way back in October 98. In a nutshell, GMR relies on four key layers per platter. The base layer is a strong antiferromagnet, onto which is paced the first magnetic layer. What this does is to align the particles in the magnetic media and "lock" them so they all lie in the same direction. Next is an insulating layer and on top of that a second layer of magnetic media. Because the thickness of the insulating layer is specially calculated, this second layer of magnetic particles also align themselves with the first layer under the influence of the antiferromagnet, but the insulating layer ensures they are not held so firmly and are thus free to move when a magnetic field is applied. When the particles in both layers are aligned, this creates a relatively low resistance when the head passes over it. When a bit of data is written however, the head actually rotates the particles in the top "unlocked" layer so they align in the opposite direction to the locked layer creating a much greater resistance which is easily detected by the head while reading. Without this technology, the media would be so tightly packed that the head would find it almost impossible to differentiate between the various states of the data bits and of course this would lead to perhaps fatal data read/write errors. The fact that Fujitsu are able to design and build their own GMR heads also gives it a distinct advantage over the competition allowing the flexible implementation of new and improved designs and the ability to get these into the channel with the minimum of delays.

Add to this a range of acoustic damping measures and a 2Mb cache , and you have one of the quietest and most reliable drives money can buy.........in theory at least.

 

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