Western Digital drives: Raptor 74 & Caviar SE 250

Storage
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May 18, 2005 by Devon Cooke and Mike Chin

Products

Western Digital Raptor WD740GD
74GB, 10,000 RPM Hard drive

Western Digital Caviar SE WD2500JD
250GB, 7,200 RPM Hard drive

Manufacturer
Western Digital
Market Price
Raptor WD740GD: ~US$180
Caviar SE 2500JD: ~US$130

Sometime around the beginning of the year, Western Digital completed a year-long transition to Fluid Dynamic Bearing (FDB) motors across their entire product line. While this transition meant little in terms of performance, FDB motors are known to be significantly quieter than the ball-bearing motors that they replaced. Since Western Digital drives have never had a good reputation for noise, does the change in motor bearings warrant revising our opinion of them? That's the question this review intends to answer.

But some of you may be wondering, What are Fluid Dynamic Bearing (FDB) motors and what are their advantages over conventional Ball Bearing Motors?

To answer this question, we turn to a white paper entitled Fluid Dynamic Bearing Spindle Motors: Their future in hard disk drives by Walker C. Blount, Senior Engineer at Hitachi Global Storage Technologies:


© Hitachi Global Storage Technologies

  • Non Repeatable Run-Out (NRRO) the highest contributor to Track Mis-Registration (TMR)... There is an upper limit at which the Ball Bearing design can no longer overcome the NRRO problem at the higher areal densities. Currently with Ball Bearings, NRRO has settled in the 0.1 micro-inch range. By contrast, FDB generates less NRRO due to the higher viscosity of lubrication oil between the sleeve and stator. FDB designs are expected to limit NRRO in the range of 0.01 micro-inch.
  • Desktop and mobile HDD track densities today are exceeding 100,000 tracks per inch (100 kTPI), which can compound the issues of NRRO. Incorporating FBD motors in the design of desktop and mobile hard drives solves many of the issues of NRRO.
  • FDB motors provide additional shock resistance beyond that of Ball Bearing spindle motors. A contributing factor is the additional surface area inherent in the FDB design. There is more conforming surface contact through the lubricant as compared to the Ball Bearings and raceway surface contact of the Ball Bearing design. Additionally, the lubricant film provides additional damping to shock.
  • The source of acoustic noise in the HDD is the dynamic motion of the disk and spindle motor components. The sound components are generated from the motor magnet, stator, bearings, and disks. These sound components are all transmitted through the spindle motor to the HDD base casting and top cover. Eliminating the bearing noise by use of FDB spindle motors reduces one area of the noise component that contributes to acoustic noise. In addition, the damping effect of the lubricant film further attenuates noise contributed from the spindle motor components. This results in lower acoustic noise from HDDs employing FDB spindle motors. Industry data has shown a 4dBA or more decrease in idle acoustic noise or some HDD designs.

There are other good reasons to take a second look at Western Digital. The Raptor WD740GD is the first (and so far only) 10,000 RPM ATA drive on the market, and, despite its billing as an "Enterprise class" drive, it is popular with the high-end gaming crowd for its fast seeks and load times. If this drive turns out to be quiet, it would be an exciting counterpoint to the truism that you must sacrifice performance to gain silence. As with most 10,000 RPM drives, the downside of the Raptor is its small capacity.

WESTERN DIGITAL RAPTOR (from WD's data sheet)
FEATURE & BRIEF COMMENT

Built for speed – with 10,000 RPM rotational disk speed and average data seek as fast as 4.5 ms. Exceeds SCSI 10,000 RPM products in workstation benchmarks.

Truly, unique in its class. There are no other 10,000 RPM ATA drives.

Enterprise-class throughput – includes Western Digital's Ultra/150 Command Queuing technology that optimizes the sequence of data transfers to the hard drive from the host, providing increased data transfer efficiency resulting in higher performance for enterprise applications. (74 GB drive only)

Useful for server performance, less so for desktop use.

Built for reliability – features a rugged, enterprise-class, mechanical platform with fluid dynamic bearings and high-end actuator.

As mentioned, FDB drives tend to be quieter than ball-bearing models.

Built to last – made for years of high-performance operation around the clock. Mean Time Between Failure (MTBF) has been calculated at 1.2 million hours.

An odd specification that is hard to interpret without a degree in statistics. Few other manufacturers list MTBF.
Built for enterprise environments – includes Enterprise Extensions S.M.A.R.T. Accessed (EESA), an expanded command set that provides SCSI-like control for server environments, as well as Rotary Acceleration Feed Forward™ (RAFF™) that optimizes operation and performance when the drives are used in vibration-prone multi-drive systems, such as rackmounted servers.
More enterprise-class features.
Built with a backing – carries Western Digital’s five-year warranty. Good long after it becomes obsolete.

Built for value – offers the performance and reliability of Parallel SCSI drives at significantly less cost.

But significantly more expensive per GB than other ATA drives.

The Caviar SE WD2500JD , the second WD under review, is a more conventional 7,200 RPM drive in a series that makes up the bulk of Western Digital drives available through normal retail channels. It is available in capacities ranging from 40 GB to 320 GB. The "SE" in its name denotes an 8 MB cache — hardly an uncommon feature any more, but enough to differentiate it from the 2 MB version.

WESTERN DIGITAL CAVIAR SE (quoted from Western Digital's data sheet)
FEATURE & BRIEF COMMENT

Fast – WD, the first to introduce an 8 MB buffer, has advanced the caching algorithms of this new and improved WD Caviar family of hard drives, resulting in next-generation high performance – performance that matches the speed of most 16 MB cache drives.

Sound like a techno-marketingspeak explanation of the drive's performance.

Cool-running – Heat is a major contributor to hard drive wear, and cool drive operating temperatures help increase long-term drive reliability. WD achieves the lowest operating temperature of any hard drive in its class, including slower drives spinning at 5400 RPM, by lowering the drives’ power consumption through advanced design of electronics and firmware.

We'll see if their "advanced design" is any more advanced than their competitors' when we examine power draw.

Quiet – Today’s PCs, digital video recorders, and gaming machines are increasingly operated in environments where noise is less tolerated. WD minimizes WD Caviar noise
to levels virtually below the threshold of human hearing with its WhisperDrive™ technology which features a highly efficient power driver design. And to cut seek noise,
Soft Seek™ technology streamlines read/write seeking algorithms, resulting in the drive operating more efficiently when accessing and writing data.

Is it possible that WhisperDriveis just FDB and Soft Seek is AAM? We don't care what it's called so long as it really is quiet.

Data Lifeguard Tools™ – software utility that works in conjunction with the embedded Data Lifeguard features (including shock protection, an environmental protection system, and embedded error detection and repair features) to make hard drive management diagnostics and repair simple and worry-free.

Freely available for download, and seemingly compatible with non-WD drives.
SecureConnect™ – provides a 500 percent stronger cable-to-drive connection than first-generation SATA hard drives and cables. Also ensures backward compatibility with legacy SATA cables and backplanes. A welcome improvement, but a proprietary cable must be purchased.
FlexPower™ – connector technology that accepts power from both industry-standard and new SATA power supplies. This last feature is a byproduct of using a PATA to SATA logic bridge.

A CAUTION: FDB MOTOR MODELS ONLY!

This review applies specifically to samples with Fluid Dynamic Bearing (FDB) motors. As mentioned, only newer Western Digital drives use this technology, so this review does not apply to older versions of the drives in question, even though they may have the same model number. In the past, there has been considerable confusion about which of Western Digital's drives use FDB motors; so much so that for a little while two separate model numbers were used to distinguish FDB and non-FDB models. Now that Western Digital has completely stopped producing ball-bearing drives, they have reverted to the previous model nomenclature.

This is not a big problem for the large capacity drives that we are reviewing — ball-bearing versions were likely produced in small numbers or never at all — but lower capacity ball-bearing models may still be available in retail channels. For example, the model number for a brand new WD1200JB (120 GB PATA Caviar SE) is the same as the original version that was manufactured with a ball-bearing motor when it was released three years ago.

The most reliable way of acquiring an FDB drive is to look for the date of manufacture printed on the exterior of the drive. Any date past January 2005 should guarantee that the drive contains an FDB motor. There is some unconfirmed anecdotal evidence that Caviar drives with black faceplates all have FDB motors.



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