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Western Digital's Caviar Green 2TB hard drive

An energy-efficient step up the capacity ladder

Manufacturer Western Digital
Model Caviar Green 2TB
Price (Street)
Availability Now

I have a theory that data expands to fill available capacity, much in the way work expands to fill available time, and Jessica Simpson expands to fill available magazine covers. If the capacity is there, we tend to use it. And why not? There's no sense in letting gigabytes go to waste.

Our thirst for capacity largely drives the storage industry. Sure, enthusiasts crave performance; we're constantly clamoring for faster seek times and higher sustained transfer rates. But most folks simply want more room to put more stuff. In recent years, most of that stuff has become digital media—pictures, music, and video, with the latter in increasingly gigabyte-gobbling high definition.

For most of the past year and a half, we've sated our appetite for capacity on a steady diet of terabyte hard drives. Hitachi was the first to reach the milestone with a 1TB Deskstar 7K1000 back in 2007. Last fall, Seagate raised the bar one notch higher with the 1.5TB Barracuda 7200.11. Now it's Western Digital's turn to claim the capacity crown with the Caviar Green 2TB.

This latest Caviar is of course interesting for its record capacity and the high areal density that enables it. The first 2TB drive is also a member of a GreenPower family renowned for energy efficiency and low noise levels, making it even more intriguing. Join us to find out if Western Digital has managed to squeeze 2TB into a drive that's quiet, power-efficient, and potentially fast enough.

New platters for GreenPower
The Caviar Green 2TB may be Western Digital's third-generation GreenPower drive, but the technology behind it is similar to existing members of the family. These drives feature IntelliSeek just-in-time drive head delivery, which reduces seek power consumption, noise levels, and even vibrations. They incorporate NoTouch ramp load tech inherited from WD's Scorpio mobile line that completely moves the drive head off the disk when it's not in use. On higher-capacity models like the new 2TB variant, a StableTrac motor also makes an appearance, securing the spindle shaft at both ends to keep the platters spinning true.

It's on the platter front that the latest Caviar Green brings something new to the table. Western Digital stacks four platters inside the drive, and each weighs in at 500GB—50% more capacity per platter than the last Caviar Green's 333GB discs.

While 500GB platters may be new to the Caviar Green, this isn't the first drive to offer such a high areal density. Seagate has been selling single-platter Barracuda 7200.12 500GB drives for some time now, and those platters have already made their way into a 1TB model. However, the company's 1.5TB Barracuda is based on 375GB platters, and it doesn't expect to hit 2TB until the third quarter of this year.

Western Digital has taken a different approach to 500GB platter deployment, electing to launch them in a flagship capacity first. The new platters will migrate down to lower capacity points in the coming months, with 500GB and 1TB models due in March. A 1.5TB Caviar Green will follow, although WD hasn't been more specific about when that drive will arrive.

When 500GB and 1TB takes on WD's fresh platter tech do arrive, they might be difficult to spot in the wild. There wasn't a problem when the Caviar Green 1TB jumped from 250 to 333GB platters because its model number changed from WD10EACS to WD10EADS. However, that's because the D actually denotes a change in the drive's cache size from 16 to 32MB. With 500GB platters, the 1TB Caviar Green will still be known as the WD10EADS, making it difficult to distinguish from the existing 333GB/platter model. Western Digital says that drives based on the new platters will quickly replace their predecessors in the marketplace, but there should really be an easy way for prospective customers to identify which version they're buying.

Speaking of unnecessary obfuscation, Western Digital remains stubborn in its refusal to publish spindle speeds for its Caviar Green line. The company will only say that the spindle speeds for these drives sit between 5,400 and 7,200RPM, with rumor, speculation, and deduction pegging speeds closer to the former than the latter. Western Digital collectively refers to the Caviar Green line's spindle speed as IntelliPower, which indicates that actual RPMs are set based on a collection of target characteristics including power consumption, noise levels, and performance. These spindle speeds are not consistent across the entire range of Caviar Greens, either; drives that use more platters tend to consume more power and generate more noise, so they likely run at slower speeds to compensate. But only slightly slower speeds—WD says that Caviar Green spindle speeds differ by no more than 5% across the line.

Having power consumption and noise levels play a part in determining the Caviar Green's spindle speed makes perfect sense, and so does adjusting the RPMs to take into account the characteristics of different platter counts. After all, it's not like Western Digital has stopped making performance-oriented drives at 7,200 and 10,000RPM. Failing to divulge spindle speeds under the guise of the GreenPower line not being a performance product is just silly, though. That's like an automobile maker deciding not to publish horsepower or engine displacement numbers for a mini-van, arguing that it's simply fast enough to get you to your destination in a reasonable amount of time.

Buffer to host transfer rate 300MB/s
Host to/from drive transfer rate 100MB/s
Available capacities 2TB
Cache size 32MB
Platter size 500GB
Idle power consumption 3.9W
Read/write power consumption 7.4W
Idle acoustics 25 dBA
Seek acoustics 26-29 dBA
Warranty length Three years

What makes this situation even more puzzling is the fact that Western Digital does publish a sort of top speed specification, claiming that the Caviar Green 2TB's maximum sustained data rate is 100MB/s. Oddly, though, that transfer rate is actually slower than the 111MB/s WD claims for the 333GB/platter Caviar Green 1TB. Even if the 2TB drive's spindle speed is at worst 5% slower, it still has 50% more gigabytes per platter, which should yield significantly higher sustained transfer rates because so much more data is available under the drive head in a given track.

Of course, we've measured such things ourselves, and we'll get to the results in a moment. The new Caviar Green's power consumption and acoustic specifications are probably more relevant than its projected performance, anyway. WD claims the drive idles at just 25 decibels, consuming only four watts in the process, which is mighty impressive for a four-platter drive. Naturally, we have the results of our own power consumption and noise level tests to pore over.

This latest Caviar Green's prodigious capacity adds a new wrinkle to the power consumption picture. It's important to think of power consumption here not just as an absolute figure corresponding to the draw of one drive, but also as the wattage per gigabyte. The Caviar Green 2TB doesn't need to be the most power-efficient hard drive around just as long as it consumes less power than other 2TB solutions, which today, require multiple drives.

Like other members of the Caviar Green family, this latest 2TB model is covered by a three-year warranty. Western Digital reserves five-year coverage for enterprise-class products and its premium Caviar Black line. Incidentally, WD is working on a RAID-optimized RE version of the 2TB Caviar Green, although there's no word on when the drive is expected to hit the market.