Almost exactly one week ago, Western Digital announced its intention to buy Hitachi's hard-drive business. The deal is still pending regulatory approval, but if it passes muster, this will be the second time IBM's storage division has changed hands in the last decade. After building up a nice reputation with the Deskstar, IBM was plagued by a wave of click-of-death failures that may have prompted the company to sell off its HDD assets. Hitachi picked up the storage unit, and while it struggled to erase the Deathstar tarnish, the industrial and electronics giant ultimately impressed by becoming the first to cram a terabyte into a 3.5" hard drive.
Today, we have another Deskstar milestone: the 7K3000 3TB. Hitachi didn't reach the 3TB mark first, though; that honor belongs to Western Digital for its latest Caviar Green. The thing is, the Caviar Green is one of those tree-hugging, 5,400-RPM models that sacrifices performance to lower noise levels and power consumption. That's fine if you're equipping a home-theater PC or want silent secondary storage to back a wicked-fast SSD system drive, but it's a little sluggish for a desktop's primary hard drive. The Deskstar 7K3000 spins its three terabytes at 7,200 RPM, and it's the only internal hard drive you can buy that does so.
A higher spindle speed gives the Deskstar a potent advantage over the Caviar right out of the gate. However, that's not the only factor to consider when evaluating the performance potential of a mechanical hard drive. One must take into account the areal density of the magnetic platters, a metric that determines how much data is accessible to the drive head with each revolution.
Western Digital has declined to reveal the areal density of the four platters it uses to hit 3TB in the Caviar Green. Simple math tells us that they offer at least 750GB of storage capacity each. Contrast that with the Deskstar, which requires five 600GB platters to reach 3TB, and it's clear that the 7K3000 isn't the top dog in every category.
Although Hitachi started reaching for higher capacity points with five-platter drives out of necessity at a time when it was behind the curve on areal density, the company says this has since become a deliberate strategy. According to Hitachi, most premature hard-drive failures can be traced back to the magnetic characteristics of the media or drive head. The more bits you squeeze into every square inch of surface area, the closer you get to the limits of your recording technology. By "not pushing the magnetics as hard," Hitachi says it can achieve better reliability than drives with higher areal densities.
Of course, it's good to have a reason for being a generation behind in platter technology. The 7K3000's 411 Gb/in² areal density is just a smidgen higher than the 400 Gb/in² Western Digital achieved with the Caviar Black 2TB, a four-platter drive that debuted some 15 months ago.
Apart from purportedly higher reliability, there is one other benefit to having a lower areal density. Packing bits more densely may be great for sequential transfers that let the drive head stay on one track and stream data as fast the spindle can spin it, but those smaller bits become more difficult to access when the drive is forced to seek them out. Remember, the drive head is trying to hit targets moving at speeds that would get you ticketed by the highway patrol. I suspect manufacturers have stopped publishing random access times in their datasheets because those times are increasing with each new drive generation.
|Spindle speed||7,200 RPM|
|Areal density||411 Gb/in²|
|Available capacities||1.5, 2, 3TB|
|Max media transfer rate||207MB/s|
|Idle acoustics||2.9 Bels|
|Warranty length||Three years|
When the Deskstar is sustaining sequential transfers, Hitachi claims it can hit up to 207MB/s. Since a 3Gbps Serial ATA interface is more than peppy enough to handle that speed, the Deskstar probably doesn't need its 6Gbps SATA support. We can't exactly knock Hitachi for supporting the latest standard, though. Besides, the drive may enjoy a minor performance boost with small burst transfers in and out of its generous 64MB DRAM cache.
Hitachi's decision to go the five-platter route with the 7K3000 has implications for power consumption and noise levels. The additional platter adds weight, forcing the spindle motor to work harder than would be necessary in a four-platter drive. This typically results in higher power consumption and noise levels. We've also noticed that drives with higher platter counts tend to be markedly louder when seeking, as if the usual seek chatter were reverberating off the additional platters.
We'll test power consumption and noise levels for ourselves in a moment. The fact that Hitachi's datasheet only lists idle numbers isn't encouraging, though.
Three years of warranty coverage rounds out the Deskstar, which is odd considering Hitachi's boasting about reliability. Three-year warranties are typical for desktop hard drives, but flagship models like the 7K3000 typically get upgraded to five years. Seagate and Western Digital offer similar coverage on their high-end XT and Black drives, respectively.
Before we move onto our test results, there are a few things you should know about the compatibility issues surrounding 3TB hard drives. Hitachi goes into more depth on this page of its website, but here are the basics for Windows users. To tap the Deskstar's full capacity as a boot drive, you need to be running a 64-bit version of Windows 7 or Vista on a motherboard with a UEFI BIOS. Otherwise, you'll only have access to the first 2.19TB. Using the 7K3000 as secondary storage doesn't require a UEFI BIOS or 64-bit OS. However, Windows XP isn't supported. If you're splurging on a $180 hard drive for your Windows XP system, perhaps you should look into upgrading the nearly decade-old operating system.