Articles: Storage

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And here are the standard bottom and top views:


Western Digital remains true to its tradition of placing the electronics board with the chips facing inward. You may note one detail missing here – there is no ATA-SATA converter chip on the visible side of the board. But it’s all right. The chip shouldn’t be there because the drive features a native SATA interface.

As you see, the PCB has only three microchips: processor, memory chip and motor controller chip.

Also you can see two acceleration sensors in the top corners of the PCB. Accelerometers of the drive measure the vibration levels and corrects the current disk operations.

By the way, about that window… Some three years ago a hard disk drive with a window was fabricated in our laboratories. I do not claim it was the world’s first device of such a kind (I’m old enough to remember the transparent cases with a pack of 5MB platters as the disk subsystem of an IBM/360), but we seem to have made it ahead of Western Digital:

In our quarrelsome times this may be enough for a legal suit, but we are not sure if we ourselves are to bring an action against WD or should be preparing against one instead. :)

But let’s get closer to serious matters now. Hard disk drives of the Raptor series have to meet tough requirements in the market sector Western Digital positions them into. HDDs that are to replace SCSI drives in workstations and entry-level servers must be fast, reliable and cheaper. The price factor isn’t a problem at all. Raptor drives cost less than SCSI ones and do not require an expensive controller (in fact, the controller is usually integrated into the mainboard and is absolutely free). The speed characteristics of the new Raptor are what we are going to explore throughout this review. Reliability is a difficult question of course, but the second generation of Raptor drives seemed to me more reliable than the first. I hope the third generation is going to be even better in this respect.

And now let’s take a look at the specs:

The new model boasts two times the storage capacity of the older one (so it can store 150GB now), a cache buffer for 16 megabytes, and support for NCQ technology. The speed of data transfers from the drive’s buffer to the host controller has remained the same at 150MB/s. That’s not a cause for grumbling since this parameter is not at all crucial for the drive’s performance.

The HDD supports Western Digital’s exclusive technologies called TLER (Time-Limited Error Recovery) and RAFF (Rotary Acceleration Feed Forward). The former is meant to improve reliability of the error-correction algorithms in RAID arrays, while the latter improves the performance of the drive when under vibration.

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