Seagate Launches Hybrid SSD Hard Drive

MojoKid writes "Though there has been some noise in recent years about hybrid storage, it really hasn't made a significant impact on in the market. Seagate is taking another stab at the technology and launched the Momentus XT 2.5-inch hard drive that mates 4GB of flash storage with traditional spinning media in an attempt to bridge the gap between hard drives and SSDs. Seagate claims the Momentus XT can offer the same kind of enhanced user experience as an SSD, but with the capacity and cost of a traditional hard drive. That's a pretty tall order, but the numbers look promising, at least compared to current traditional notebook hard drives."

Comments

Manageable hybrid

[Thanshin]

Hybrid storage drives should be manually manageable.

You should have the possibility of configuring which files/folders/partitions/whatever you want to be accessed fast and which parts are to be left as "long term", slow access, storage.

Re:So they make a hard drive with a cache?

[dingen]

The difference between this drive and every other drive on the markt is not the fact it has a cache. Every harddisk has a cache. The difference is: this drive has a 4 GB cache. And because it's an SSD cache and not (as you suggest) a RAM cache, it maintains it's state even between reboots, so your computer is fast right from the start.

Re:Or wait..

[dingen]

SSD wont be as cheap per GB as traditional drives for many years to come. Chances are that even when a 500 GB SSD drive gets to an acceptable price point, an old-fashioned hard drive would still be cheaper and hold many, many more data at the same time.

This solution provides a cost-effective way to have both performance and storage *right now*.

Re:No, not really

[Bigjeff5]

4GB is just a cache file, if you are lucky it caches the right files but if you are doing complex stuff these "smart" caches often get horribly confused and start caching the wrong data.

You do realize that the reason your computer is so fast is because of progressive layers of cache, right?

The fastest cache on the system is L1 cache. It's also the most expensive. Next is L2 cache, which runs at about 1/10th the speed of L1, but it's much cheaper and so there can be more of it. That it's only an order of magnitude different means the larger L2 cache has time to fill the L1 cache before the L1 cache is completely empty. Then comes L3 cache (usually), which is again about 1/10th the speed of L2, and it keeps the L2 full. Then RAM, which has kept pace pretty well and is about 1/10th the speed of L3 and keeps L3 full. And here is where things break. RAM speeds are measured in nanoseconds. Spinning disk hard drive speeds are still measured in milliseconds, and not even 1 or 2 milliseconds, more like 5-10 milliseconds. That's a couple orders of magnitude slower and breaks the chain of cache that we had going, and it is not enough to maintain full RAM at all times. What we need is a cache that is about 1/10th the speed of RAM to sit between RAM and Hard Disk.

SLC Nand flash, with its sub-millisecond read and write times, fits the bill perfectly. It's basically a scaled up version of the caching they use on hard drives already, and because of its size should be much, much more effective.