Seagate Reinvents the Hybrid Laptop Hard Drive

Seagate is having a second crack at SSD hybrid hard drives, a technology for boosting drive performance by adding flash memory to a conventional hard drive.

The company has launched the new 2.5-inch Momentus XT, a hybrid HDD and flash design that follows on from Seagate's first foray into the concept nearly three years ago, the Momentus 5400 PSD, which sank without trace.

The company now admits that the 5400 PSD's performance just wasn't good enough but is confident that the new Momentus XT will overcome the earlier drive's shortcomings.

The technical spec suggests that this time Seagate might be on to something.

Unlike the PSD, the Momentus XT can work with any operating system and BIOS (the PSD was Windows Vista-specific), and the amount of onboard SLC NAND flash memory has increased to 4GB from the older design's 256MB. The drive also features 32MB of level one drive cache and a faster spin speed of 7,200rpm.

The benefits of the SSD flash are faster boot times and for more rapid access to commonly-used application executables, but how does it actually know what to put into the SSD cache and what to leave on the hard disk?

According to Seagate, the first time the drive is started in a laptop, it goes into 'learning' mode that resembles the performance of a conventional drive. By the second boot, the onboard adaptive memory algorithms have worked out which OS and app files it needs to store to boot more rapidly and from that point on users will see the speed ramp.

Seagate's own figures who that the drive will boot Windows 7 in 23 seconds, compared to 18 for a pure SSD and 59 seconds for an equivalent 7,200rpm 2.5 inch laptop drive without flash.

Application loading improvements vary from app to app, with iTunes ready to run in 4.8 seconds compared to 18.4 for a conventional drive, Adobe Premier Elements loading in 40.2 seconds (hybrid)compared to 50.1 (HDD), and Excel managing 9.2 seconds (hybrid) as against 11 seconds (HDD).

That said, these figures compare the new XT with a fast 7,200rpm drive when most laptops come with slower 5,400rpm drives, suggesting that the real-world performance might be more marked for the average user.

According to Seagate, the XT will allow ordinary laptop users to get most of the benefits of SSD technology, such as fast booting and application cacheing, without the prohibitive cost of a pure SSD drive.

Bare metal prices for the drive are said to be around $50 more than the same spec of drive without the hybrid design, or $113 (250GB), $132 (320GB) and $156 (500GB). At that price, many users will be tempted. The drive can also be retrofitted to older machines without the need for special drivers of modifications of the BOS.

The Seagate Momentus XT is available from today in the Asus ROG G73JH system which features two Momentus XT drives. Shipping dates for the drive on its own have not been confirmed.

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