Seagate Momentus XT 'SSD killer' Hard Drive Revamped

[Biswajit.HD]

Seagate has announced the next version of its Momentus XT 'hybrid' hard drive, a design that pairs a traditional spinning hard disk with a large cache of flash memory as a way of boosting performance without the expense of a full-blown SSD drive.
Dubbed the 'SSHD' (solid state hybrid drive), the latest version of the Momentus XT doubles the size of the onboard Single Level Cell (SLC) flash to 8GB, adds support for the higher-throughput SATA 6Gb/s interface, and ups the data capacity at which the drive can be bought to 750GB, all useful upgrades from previous versions.

The drive also adds improvements at firmware level, starting with 'Fast Boot' which allows a system to boot almost as fast as a far more pricey solid state drive (SSD) by permanently storing boot files in the fast-access flash partition, the company said.

Tests numbers supplied by Seagate showed a Dell XPS laptop booting in 54 second with a conventional 7200rpm drive, 11 seconds with an Intel 320 SSD and only 14 seconds with the Momentus XT. This is impressive but a lot will hang on Seagate being able to back up these bold performance claims.

A subtle improvement is Fast Factor Flash Management, an invisible software layer that constantly adjusts the way the drive is accessed by the OS in order to optimise its use of fast flash memory and slower hard disk as appropriate.

This is perhaps the most surprising aspect of the Momentus XT sales pitch; Seagate sees hybrid drives not as a compromise between SSDs (speed) and hard drives (low cost and high capacity) but for almost all users as being innately superior to either.

The performance, then, will match an SSD in most scenarios without costing the earth or restricting capacities, and will also deliver this without the disadvantages of SSDs and hard drives when used separately, the company said.

Hard drives wear out but an SSD minimises this wear by keeping as many files as possible in flash memory; SSDs also wear out after a given number of write cycles, so the XT minimises writes to the cache and uses the hard drive once it has learned which files should be placed in which type of memory. It all makes sense – in theory. "Most people are used to performance declining over time but our drive [the XT] gets faster," said Seagate product marketing manager, Joni Clark. "It's flash SSDs for the masses."

Seagate's hybrid technology made its first appearance as far back as 2007 with the Momentus PSD. With a tiny flash cache (at the time flash chips were expensive) and lacking even native support inside Windows, the product was more of a marker than a serious sales contender.

This was followed in 2009 and finally 2010 with dramatically improved Momentus XT designs, which boosted onboard cache to 4GB and added new firmware and the ability to work independently of the operating system.

Despite the obvious improvements, the design has experienced some technical wrinkles, including a reported problem in some systems that stopped the drive spinning down correctly in power-saving mode. Some users reported bluescreen of death issues when using the drive on older computers, although it should be pointed out this can also happen with conventional drives.

source : pc world