Western Digital's Caviar Green hard drive

Western Digital has long been a performance leader in the hard drive world. That made it especially odd when the company debuted its first terabyte in the "GreenPower" Caviar GP. Despite what enthusiasts might have hoped, GreenPower didn't mean "Hulk smash." Instead, it referred to the drive's eco-friendly motor, whose slower spindle speed dramatically reduced power consumption. WD had driven to the terabyte party not in a performance-oriented sports car, but behind the wheel of a tree-hugging econobox.

To be fair, the Caviar GP's performance was surprisingly good for a drive whose platters spun at close to 5,400RPM. In some tests, it was even faster than terabyte drives spinning at a full 7,200RPM. The GP also lived up to its energy-efficient billing, sucking half the power of some of its terabyte rivals, all while barely making a whisper.

Since its release, a reshuffling of Western Digital's hard drive branding scheme has transformed the Caviar GP into the Caviar Green. Now it's time for the drive itself to change. The original Caviar GP reached the terabyte mark with four 250GB platters, but the latest model we'll be looking at today has been upgraded to 333GB platters, of which it needs only three.

The higher areal density of the Caviar Green's new platters promise improved performance, and since the drive is spinning only three of them, power consumption should drop as well. On all fronts, then, this latest Caviar Green looks better than the original. Let's see if it is.

A denser shade of green
The idea behind the Caviar Green is a simple one. For some applications, be they home theater PCs, secondary desktop storage, or a home file server stuffed into a closet, you don't need the fastest hard drive on the block—just one that's fast enough. Those markets are likely to prefer drives with lower noise levels and power consumption, which the Caviar Green is more than eager to provide, ideally while maintaining an acceptable level of performance.

It might be counter-intuitive for an enthusiast to give up any performance, but the trade-off makes sense here. At least in consumer markets, most folks buy hard drives looking to expand storage capacity for their multimedia libraries. You don't need a fast hard drive to store or smoothly stream even the highest definition video content, and your multi-gig MP3 collection certainly doesn't need to be on a 10K-RPM VelociRaptor.

When it first launched the GreenPower Caviar, WD refused to disclose the drive's actual spindle speed, saying only that it was somewhere between 5,400 and 7,200RPM. The company later admitted that the drive ran at closer to the former than the latter, but we haven't been able to coax out an exact spindle speed.

Numerous sites have speculated that the Caviar Green essentially runs at 5,400RPM, and now even Western Digital has changed its tune. Sort of. The drive's latest spec sheet lists the Green's rotational speed as "IntelliPower," which WD defines as "A fine-tuned balance of spin speed, transfer rate and caching algorithms designed to deliver both significant power savings and solid performance." So much for clarification.

Western Digital obviously doesn't want customers making assumptions about the Caviar Green's performance based on rotational speed alone, but the decision to obfuscate it behind blatant marketingspeak is entirely unnecessary and evasive. After all, the market isn't short on examples of drives with slower spindle speeds outperforming faster ones. One need look no further than our most recent mobile storage round-up to see Western Digital's own 5,400-RPM Scorpio Blue beating Seagate's 7,200-RPM Momentus in some tests. Consumers deserve a little more credit. Those nerdy enough to dig through data sheets or online reviews to find a drive's spindle speed are going to know that it's not the only factor that dictates performance.

Enough with the soapbox, though. We have a drive to test. The latest addition to the Caviar Green lineup can be identified by its WD10EADS model number. You'll want to write that down, because the old drive's model number is WD10EACS. The drives themselves are quite similar, with the biggest difference coming on the platter front. Western Digital has replaced the original's quartet of 250GB platters with a trio of platters that weigh in at 333GB each. This 33% increase in areal density enables the Green to offer a terabyte with fewer platters, allowing the motor to spin less weight, which further reduces the drive's already low power consumption. The higher areal density of these new platters should also improve the Green's sustained transfer rates by spinning more bits past the drive head in a given span of time.

Western Digital's second GreenPower upgrade is applied to the drive's cache, which has been bumped from 16MB in the original to 32MB in this latest model. For quite some time, WD insisted that its own internal performance testing showed little benefit to cache sizes larger than 16MB. The company's recent jump to 32MB may be more to keep up with the Joneses than anything else.

Apart from new platters and more cache, the latest Caviar Green shares the same mechanical underpinnings and features of its predecessor, including the IntelliSeek just-in-time drive head delivery mechanism. Rather than racing the drive head across the disk as fast as possible, IntelliSeek uses rotational latency to its advantage, only moving the drive head as fast as necessary to get it into position for the next data point. Western Digital claims IntelliSeek can lower not only drive power consumption, but also seek noise levels and drive vibration.

Like most hard drives, the Caviar Green is covered by a three-year warranty. That's still two years short of Seagate's across-the-board five-year warranty, although it's worth noting that Western Digital covers its high-end Caviar Black drives with a five-year term.