Fast And Smart: Seagate Barracuda 7200.7 And Western Digital WD740 Raptor
Hardly any PC component breaks new ground with its advances as unspectacularly as the hard drive. Users think of it as a little box that occasionally grinds and whirs, while remaining in the background most of the time with a quiet hum. However, expectations for it are high: Users don't like wait times, and even errors shouldn't occur, if at all possible.
But structure is what determines the practice of hard drives: We're referring to electromechanical hybrids consisting of electronic components and numerous propelled parts. That's the hitch, because wherever mechanical problems occur, symptoms of wear and tear and particularly wait times (so-called latency times) cannot be avoided.
The maximum data transfer rate is not necessarily crucial; 60-70 MB/s should really be enough for many applications. It is more important than ever for operation to be as efficient as possible so that head vibration is reduced to a minimum - and what's more, it has to be so responsive that latency times can be avoided.
To make this happen, however, hard disks must get considerably smarter than they are now. The main thing needed for this is the knowledge of a hard disk about its physical structure, consisting of disks (platters) writeable on both sides, including read/write heads, division of the platters into tracks and their subdivision into blocks. That would allow a disk to process incoming commands for more efficient response times. A side benefit of enhancements like that would be a longer useful life for the hard disk, thanks to less mechanical strain.
The approach is taken from SCSI technology and is called native command queuing. An NCQ-compatible device, i.e. one that conforms to serial ATA II specifications, can accept up to 32 commands and process them in an optimized sequence. The forerunner in this respect is Seagate and its Barracuda 7200.7, which already supports NCQ. Thanks to its native serial ATA interface, which works without converters (or so-called bridges), this drive can be considered the best serial ATA model from a technical point of view.
Western Digital has already created quite a stir with the WD360 Raptor - at 10,000 rpm, it is the fastest SATA hard disk, making it good enough even for demanding server environments. And now, the next WD740 generation, with dual capacity (74 rather than 36.7 GB) and command queuing. We received a pilot series model for testing with performance data that couldn't be changed.
To use NCQ we needed a controller with appropriate support. Silicon Image supports this with software (driver) for the current Sil3512 and Sil3114 chips, but has not yet released them. The successor model, Sil3124, will support NCQ with hardware.