Western Digital Raptor WD740GD Preview

Western Digital Raptor WD740GD Capacities Model Number Capacity WD740GD 74 GB Lowest Real-Time Price: Introduction Early this year, Western Digital caught the attention of the enthusiast community with its announcement of the world's first 10,000 RPM ATA drive, the Raptor WD360GD. Featuring a serial ATA interface coupled with top-notch mechanics, the Raptor aspired to deliver multi-user performance rivaling that of enterprise-class SCSI drives at a fraction of the price.

Ironically, it appears the Raptor may have met its greatest success not in the server market but rather with the enthusiast/gaming community itself. The drive lacked a key feature, tagged command queuing, which prevented its performance from scaling up under multi-user loads as adeptly as the typical SCSI drive did. Further, the Raptor's firmware, designed by a company that had already proved itself as the best at optimizing for the desktop, allowed it to match and even exceed the single-user performance delivered by the latest-generation 10k RPM SCSI units. Retailers such as Alienware, Falcon Northwest, and even Dell offer the Raptor as an option on their high-end desktops. The drive even appeared wrapped in retail packages at certain brick-and-mortar superstores.

StorageReview.com's initial Raptor was provided by long-time sponsor Hyper Microsystems. As an engineering sample, the drive proved to resellers that WD was capable of manufacturing SATA 10k RPM units. They did not, however, incorporate near-final firmware and also lacked a key feature, device-level write caching. In the end, the beta unit delivered lackluster performance.

Western Digital quickly responded by supplying an evaluation unit that was to represent the performance one could expect from the shipping product. This second sample featured more recent firmware and had write caching fully operational. Further, it featured a more aggressive zone layout that yielded a maximum transfer rate of 63 MB/sec, up from the first sample's 57 MB/sec. Buoyed primarily by enabled write caching, the Raptor seized a top spot in the StorageReview Desktop DriveMarks.

As users got their hands on retail drives, however, they quickly noticed that their shiny new hotrods topped out with 57 MB/sec transfer rates rather than the 63 MB/sec that SR's WD-supplied sample boasted. Sequential transfer rates (STR), unfortunately, are the easiest HD performance metric to measure and also the least indicative of how the drive will perform under real-world situations. It was obvious from the lower STR figures that the shipping Raptors incorporated the more conservative zone-layout found in our original sample rather than the one used in the following unit.

Conspiracy theories ensued in the community. Eventually, a flawed consensus was reached: If the shipping Raptors featured the lower transfer rates exhibited in SR's first sample, then the write-caching, firmware, and performance of shipping units must also be similar to that of the first drive's. This logic, of course, is fallacious. Zone configuration (and thus transfer rates) is independent of write caching and firmware.

We eventually contacted Western Digital on the issue. The firm responded by stating that while they had initially hoped to ship Raptors featuring the more aggressive zone layout, yields on such platters were too low and as a result would knock the Raptor above its targeted price. To meet the drive's price point, WD reverted to the more conservative setup.

Afterwards, Hyper Microsystems supplied us with a third, retail sample. Around the same time, to fix unrelated problems in another serial ATA drive review, we were forced to update our normally-static Testbed's SATA controller's BIOS and driver. Hence, a proper comparison between the second (higher STR) and third (retail) samples required a retest of the second drive. Let's briefly recap the tested differences:

Basically, while the third sample's transfer rate slid by about 9%, most application-level marks fell by about 3%. Only the Bootup DriveMark, heavily dependent on transfer rates, fell by a more significant margin. The average loss of 3% elsewhere likely comes from more conservative firmware, as a change from 63 MB/sec to 57 MB/sec simply does not impact today's applications in a meaningful way.

The bottom line? Despite the lower-than-anticipated transfer rates, the Raptor nonetheless was easily the fastest ATA drive ever and the ideal mix between price and performance when both ATA and SCSI drives were considered.

Since then, however, Hitachi Global Storage Technologies introduced the marvelous Deskstar 7K250. Though incorporating a more conventional 7200 RPM spindle speed, the 7K250 nonetheless features a wide capacity range combined with performance that approached WD's speed demon. Does Western Digital have anything else up its sleeve?

Enter the second-generation Raptor! Announced September 15th, WD's revised offering promised to address nearly all of the complaints leveled against the firm's first entry. Maintaining the line's unique 10,000 RPM spindle speed, the Raptor WD740GD features the following improvements:

• 74-gigabyte capacity - perhaps the most significant improvement is the migration to a two-platter flagship design. WD also plans to introduce a revised single-platter, 37 GB unit, though perhaps not until most WD360GD units sell through the market.

• 37 GB Platters - the aggregate areal density of the new Raptor will remain the same as the first. Linear density, however, has been increased, to achieve:

• 72 MB/sec outer-zone transfer rates - though STR remains non-consequential in the large majority of uses, some folks were disappointed with the 55 MB/sec that the first Raptor delivered. WD is confident enough with new yields to spec a transfer rate that rivals the best available from today's disks.

• 4.5 millisecond seek time - the Raptor WD360GD specs at 5.2 milliseconds.

• Firmware-level TCQ - matching a feature available on all contemporary SCSI drives, the new Raptor will feature tagged command queuing… that is, device-level reordering of outstanding requests for more efficient service times.

• FDB motors - though quiet from an emitted sound-pressure perspective, the original Raptor emitted a slight high-pitch idle whine that could irritate sensitive ears. WD has been on the slow side when it comes to migrating to fluid bearing motors when compared to other manufacturers. Fortunately, the new Raptor uses quieter and ostensibly more reliable FDB motors.

Maintaining a 5-year warranty and adding command queuing, with the new Raptor WD once again sets its wanton eyes on the low- to mid-end server market currently enjoyed by today's 10k RPM SCSI drives. Of course, the manufacturer must also take care to ensure that the drive's blazing desktop performance does not suffer.

Interestingly, the new Raptors will still use an onboard PATA-to-SATA bridge disdained by many enthusiasts. When hot-swap functionality, command queuing, and the potential for blazing performance remain, however, why should we care? Performance and functionality, not PCB layouts, remain the bottom line. As has been the case with all bridged solutions (that is to say, all serial ATA drives except Seagate's Barracuda series), the new Raptor features both a newer 15-pin power connector as well as the more traditional 4-pin molex receptacle.

Western Digital recently supplied StorageReview with an engineering sample of the 740GD upon which we have based the following preview. We have been putting it through its paces over the last two weeks in a variety of objective and subjective scenarios. Before we turn to the numbers, let us keep a key point in mind- this drive is an evaluation sample. It lacks the tagged command queuing that WD promises will be enabled in shipping units. What kind of impact does the lack of TCQ have in our tests? In the server suites, this sample will not scale upwards as effectively as a SCSI drive under heavier loads. Under single-user situations, ramifications are not quite as clear. Even with heavy multi-tasking, generated queue depths remain relatively light. As a result, command queuing may not help- it may even exact a penalty. More generally, remember that all things are of course subject to change between this engineering sample and final retail products.

That said, let us see how this eagerly anticipated drive stacks up!