WD's New 400GB SATA Drive Promises Enterprise Reliability

For starters, let's acknowledge that the hard drives of today are more reliable than the hard drives of old--period. The drive industry is one of those lovely business examples where every year you keep getting significantly more for your dollar, and product quality just keeps improving. But drives still fail. And over time, chances are you'll have the unenviable experience of being there in person to see it happen. Most of us who have been tapping the keys since the days of DOS have all already experienced at least one drive failure. Even if you handle your hard drives with ultimate care, avoiding excessive heat, vibration, shocks, and power surges--?you're likely to lose one sometime anyway. With that in mind, experienced (and just-plain-cautious) users will find the promise of an unusual level of reliability quite attractive--especially when that reliability comes with a five-year full-replacement warranty.

Western Digital's new WD Caviar RE2 SATA hard drive is designed for use in the enterprise--where high reliability is job one. The good news for desktop users is that the RE2's enterprise designation does nothing to prohibit using this $289 drive in your desktop PCs. Like most desktop hard drives today, this second-generation high-capacity model is a 7200-rpm unit--unlike its lower-capacity (74GB), 10,000-rpm WD Raptor sibling. The RE2 pushes capacity to 400GB, has a larger-than-usual 16MB buffer, and includes a bevy of features designed to improve longevity and day-to-day performance.

We have never touted mean time between failure numbers because we don't have the resources to verify them: It takes about 1000 drives and a bunch of sophisticated lab equipment to come up with these projections. In addition, different vendors have different methods of arriving at their MTBF numbers--so if we mention them at all, we always let you know that we're passing along a vendor spec. With that caveat in place, WD's rating for the Caviar RE2 is 1.2 million hours at a full 24/7 duty cycle. For what it's worth, that's the longest MTBF projection that I've heard of on a SATA drive. (If you do the math, 1.2 million hours comes out to almost 137 years. We should hope to last that long too, right?)

SATA-interface drives are attractive to enterprise users because there are plenty of ways to put high-reliability SATA units to work while avoiding the high price of SCSI and fibre channel drives. WD has designed in plenty of perks for enterprise users. For example, the company's use of RAFF (Rotary Accelerometer Feed Forward) technology is designed to maintain performance in RAID configurations where vibration can be a real performance killer. RAFF employs advanced firmware and sensors to compensate for vibration, and according to WD, that combination pays off handsomely as vibration reaches higher levels.

Another feature that's useful in enterprise arrays is TLER (Time Limited Error Recovery), which WD says allows these less-expensive drives enough time to perform error recovery functions without getting dropped from an array. Keeping all the drives in an array up and running reduces service calls and also ensures greater data reliability. WD says the drive will interconnect seamlessly with Serial Attached Storage architectures.

WD has also implemented Native Command Queuing on the RE2. NCQ provides a big payoff in server use by allowing the drive itself to complete data requests in the most efficient order--rather than in the order the request were made. The drive's use of NCQ intelligence allows it complete these tasks with no intervention from the CPU. Desktop users should not expect great benefit from NCQ, however. The RE2 provides a 150MBps maximum transfer rate. WD says that it made the decision not to aim at the higher 300MBps capabilities outlined in the latest SATA spec for two reasons: Sticking with the lower limit helps enable greater overall reliability, and there's currently little benefit achieved using drives specced to the higher limit in most server applications.

The reasonably priced RE2 is bound to be an attractive offering for enterprise buyers. But it's also likely to interest a fair number of people working on a desktop upgrade. It's a big world, and some good hard drives will always go bad. Under those conditions, the RE2's ultra-long warranty and promise of high reliability are worth considering. (For ratings of hard drives that we've wrung out in the PC World Test Center, check out our "Give Your Storage a Boost.")