Is There a Market for Hybrid Disk Drive?

In 2007, Samsung (SpinPoint MH80) and Seagate (Momentus 5400PSD with 256MB on flash, another one never came to market) launched the first hybrid disk drives integrating HDDs with NAND flash memory as a cache to accelerate the devices. There was not market and it was a big flop as the OSes were not able to take advantage of this new technology.

With Vista, Microsoft adds a series of drives, Readydrive, enabling to manage these hybrid units, but with poor efficiency.

That’s why Seagate decided to put directly into its new Momentus XT (see the today’s press release) a special new controller to do it in a better way and independent of any operating systems. Called Adaptive Memory and developed by its own engineers in Longmont, CO, the patent pending technology manages the flow of data between the magnetic disk and the flash memory, but only when the computer needs to read – not to write (the write goes to the drive first, then is mirrored to the solid state memory). It includes algorithms that detect the user’s profile to find the files most frequently used and then transfer them through the faster 4GB SLC flash cache.

We met Mark Wojtasiak, Seagate’s senior marketing manager, global market development, who tries to convince us by showing a lot of benchmarks. Two nice girls, each one with a notebook, one including a regular HDD, the other one with the Momentus XT, started at the same time their computer. It’s not the first time we saw this kind of marketing demo and you will see many more in the future, generally to compare HDDs and SSDs. It’s always faster with flash, of course. And here it was with the Momentus XT. Wojtasiak also said:" Our Momentus XT is faster than 10,000rpm SATA 2.5-inch WD unit."

We also add a small advantage that Seagate didn’t mention: if the magnetic disk crashes, a data recovery service could at least recover the most frequent used files in the flash memory.

Better speed with hybrid devices will depend fundamentally on the usage of the notebook. For games, it’s perfect. To boot, it’s faster. But you will see no improvement at all when writing or when the flash cache does not contain some files you wish to read because yo use them not so frequently. If the file you want to get from the disk has a size greater than 4GB, it has to be read on the magnetic platters.

Now into the the Momentus XT, you have three tiers: 32MB DRAM, 4GB flash as caches, and 250GB, 320GB or 500GB magnetic memories. But caches are "placebo" that globally accelerate the computer, but not always. With DRAM or SSD only, the speed is permanently increased and with better reliability and lower power consumption.

You have to pay a premium to get an hybrid drive rather than a regular HDD. Seagate makes an effort to diminish the difference of the costs between both units. Here is a comparison of the prices with the company’s 7,200rpm  2.5-inch HDDs, according to Wojtasiak:

• 250GB: $60 to $70 for HDD, $113 for hybrid (+61% to +88%)
• 320GB: $70 to $80 for HDD, $122 for hybrid (+53% to 74%)
• 500GB: $90 for HDD, $156 for hybrid (+73%)

Until now, Hitachi GST and WD ignored hybrid HDDs and proved that it was a good decision. Samsung could come back and Toshiba may enter into this market with the advantage to be flash chip manufacturers.

Everybody knows that hybrid drives will be finally replaced by SSDs and will have a short life. How long? We reiterate our bet that, in five years, all the notebooks will integrate SSDs only.   

Among the Seagate’s announcement, there is also the discrete release of a 2.5-inch HDD, 9.5mm high, at 750GB and 7,200rpm with 3Gb SATA. We presume that the company will sell more of these Momentus 750GB than the Momentus XT.