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Seagate Thinks Faster, Larger in New Disk Drive

Seagate today unveiled the Barracuda XT, a new addition to its family of internal desktop hard drives, sporting an ultra-fast 6 Gb/sec. SATA 3 interface and 2 TB in capacity, the largest amount supported by most Windows PCs. It also boasts a whopping 64MB of cache.

So, why would the world need a faster drive interface and so much storage in a single unit?

"HD video, HD gaming all are taking up more space," David Burks, director of product marketing at Seagate (NASDAQ: STX), told InternetNews.com. "We believe that there are segments out there that immediately leverage this drive, one of them being Non-Linear Video editing."

Another industry evolution in this drive is the number of bits that this drive can fit into a tiny space.

"Areal density is 368 Gb/sq. inch on this drive -- that puts it in a leading position of offering a four-platter, 2TB system."

Burks also said that with the higher density, Seagate has an advantage of power and efficiency over Hitachi's five-platter 2TB disk.

In theory, however, more heads like in Toshiba's design can also mean faster access, increasing the likelihood that another head may be sitting over the data you might want and can get to it more swiftly.

Of course, actual performance depends on a number of factors -- rather than raw performance specifications such as transfer rate, it also hinges on accessing the data. As with all hard drives, the heads need to get to the data you want; then, transferring it to the user depends on how much data is passing under a head in a given amount of time.

At only 7200 RPM, this drive is less than half the potential transfer speed of high-performance enterprise-level SCSI drives, so can this interface's speed increase really matter?

"We have seen in our early [Futuremark] PCMark Vantage's video editing, benchmark testing shows about a 47 percent improvement in speed over our standard Barracuda 1TB 32MB cache with the 3Gb/sec. SATA II interface," Burks said.

This is in part to programming: in video-editing applications, software can guess what you will need nest and "pre-fetch" that data, putting it into cache for speedier access than reading directly off the platter. With a larger cache of 64 megabytes, the idea is that this makes a difference.

Besides software, another way to improve performance is to use some of Seagate's technical tools to actually reduce capacity with a technique called de-stroking or short stroking.

"If capacity is limited to, for example, 300GB, then throughput can increase by about 20 percent," Seagate said.

The reason is that the surface near the outside edges of the hard drive move faster than the inside edge. Image a car at the extreme outside lane of a curve, which needs to speed up to complete the turn in the same amount of time and a car on the inside lane. The faster the heads move past the data, the more information can be read from the surface and sent to the motherboard.

A much more efficient and easier way to "short stroke" a drive can be by creating partitions: a small partition first created on a drive will have a similar boost in speed over a short stroking technique, as long as the rest of the drive is never used concurrently.

Seagate said that the drive new drive, ST32000641AS, will start shipping today.

Update to this story corrects comparison to Hitachi drives.