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Unfortunately, the NAND for the Momentus XT is on the other side  (Source: Seagate)
Complete redesign combines speed with affordability

The promise of superfast access speeds has been fulfilled by solid state drives using NAND flash memory, but it comes at a high monetary cost. Many enthusiasts, prosumers, and corporate users have already adopted SSDs as hard drives are typically the primary bottlenecks in a computer system. While CPUs and RAM measure their access speeds in nanoseconds, traditional magnetic-based hard disk drives are still measured in milliseconds.

The primary advantage for HDDs is the low cost of production, even for faster 7200 and 10k RPM drives. Samsung and Seagate tried before to bridge the gap between low-cost HDDs and fast SSDs using a hybrid hard drive, combining a single magnetic platter with a small amount of NAND flash memory. The NAND would act as a cache, similar in theory to a small scale tiered storage solution like that used by many corporations for their datacenters.

However, the experiment failed. NAND was still too expensive in 2007, and the small amount that was used proved insufficient. Performance turned out to be worse in some situations, and the capacity of Seagate's sole model was soon overtaken by other products with higher areal density.

Now, three years later, Seagate has learned its lesson with its all new Momentus XT. The company calls it a Solid State Hybrid Drive, and it will be available exclusively in a 2.5-inch form factor. There are 250, 320, and 500GB models, all of which feature 32MB of DRAM cache and a 4GB single-layer cell NAND flash cache. There will unfortunately not be any 6Gbps SATA support, despite the XT moniker.

The secret sauce this time is what Seagate calls "Adaptive Memory". The firm has developed new algorithms based on their years of research and producing firmware for regular drives. These algorithms monitor data access transactions over time, and will place a copy of the most frequently accessed data (such as Windows system files) onto flash storage. A table also keeps track and counts of how frequently data is used in order to prioritize it for retention and caching.

This is similar in concept to Microsoft's ReadyBoost, but uses much faster SLC rather than the sluggish commodity NAND that ended up being used in USB flash drives and SD cards. The algorithms are also much more advanced, as is the garbage collection and firmware. Seagate developed its own proprietary NAND flash controller specifically for the Momentus XT.

This also means that the Momentus XT is also operating system agnostic, and can be used with Unix/Linux environments and MacBooks.

Seagate insisted on using the flash as a cache instead of primary storage for additional reliability. Their tests show that over 250GB of data a day could be written to the NAND for 5 years and it would still function.

Although the Momentus XT isn't as fast as an SSD, Seagate thinks that it will be close enough that its customers won't be able to notice the difference qualitatively. While most consumers will notice the difference between a 5400RPM drive and a 7200RPM drive, they might not necessarily notice the difference between a 7200RPM and 10k RPM drive, an argument that the company has used before as a justification for not producing a 10k RPM consumer drive.

To continue the example, Seagate likens the Momentus XT to a 7200RPM drive and SSDs as 10k RPM drives; while the SSDs are much faster, qualitatively consumers won't notice the difference. The company expects that it will be able to hold off the SSD onslaught for a couple of years with this strategy, despite the lowering cost of NAND flash memory. In fact, as NAND flash prices drop due to the introduction of new process nodes, Seagate will be able to fit more NAND into the same space and offer even greater performance.

The first OEM to adopt the Momentus XT will be ASUS for their ROG G73JH gaming laptop, which will feature two of the drives. Seagate will also be shipping Momentus XT drives out to the channel this week for retail distribution.

Two reviews of the new Momentus XT can be found here and here.

Momentus XT








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RE: Waste of time; skip to the final product
By atlmann10 on 5/24/2010 12:16:17 PM , Rating: 2
Your completely right Myg, this is a gimmick nothing more. The layout you outline is much more like it I personally would up the Flash to be even with the RAM though. SO 500GB Magnetic/5Gb Flash/ 5GB RAM. I would also make the controller separate the drives or at least Flash and Magnetic for a default auto Trim defrag routine.

The one realization here is there trying to protect a profit margin. These companies make the drives the lower there profit per device or component, and the amount specific to type with that impact everything for the company. There profit to cost ratio right now favors greatly the magnetic side of this issue.

So this is a stop gap development to slow the adoption ratio. They make far less on a true SSD. As cost's for materials drop as well as market acceptance as a norm more NAND will be produced. It will also become cheaper materials wise as well as faster, more secure, and longer lasting.

If you look at the development to market acceptance to price ratio of anything even magnetic hard drives you will see that. Then compare price to size and you will see the rest. I don't know if I would call it irrelevant though as the market has to go through all this for it to become a norm.

So it is necessary!

RE: Waste of time; skip to the final product
By Myg on 5/24/2010 5:03:13 PM , Rating: 2
Thats just company status quo propaganda, there is always a way to provide similar functionality/etc without having to go down the hard route. They just do it as an excuse for gouging people. In this instance they could of designed an exterior frame type system where you slot in your own HDD and SDD and RAM (if we want the proper hybrid) with attached controllers/etc on a seperate board.

Most things we dream are acheiveable, and if you follow the order that those around us lay down, you will doom to always be in their shadow.

RE: Waste of time; skip to the final product
By Myg on 5/24/2010 5:05:02 PM , Rating: 2
will doom to always:Correction: be doomed to always...

RE: Waste of time; skip to the final product
By Jansen on 5/24/2010 6:40:20 PM , Rating: 2
While I too would like to see more, the specifications you set would barely fit into a 3.5 inch form factor. Not to mention that Seagate is using 4GB of SLC; a 32GB drive would cost you about $400 alone. 4GB of RAM would be $100, so even if you used slower MLC you would still be looking at a minimum cost of $300, which is the price of most notebooks today.

So it would be much more cost effective for someone to use a SSD boot drive, HDD, and get more RAM, which kind of defeats the point of an affordable alternative to expensive SSDs .

It's easy to criticize, but if it was that easy (and cheap) to do Seagate would've done it and wiped out all of its SSD competitors.

RE: Waste of time; skip to the final product
By bfonnes on 5/24/2010 8:52:28 PM , Rating: 2
The principles behind your argument are generally valid, but don't say that notebooks cost $300 as they most definitely do not. I believe that it was implied by the OP that they would be willing to pay more than the price of the lowest cost SSD to own what was suggested. On a side note, authors should refrain from commenting/trolling on their own blog articles, IMHO. no offense meant... but, if the article is strong enough, then why the need for comments to support your point of view? Also, I don't see everyone purchasing SSDs for laptops only, today. I see most enthusiasts having their desktop be their hobby/expensive machine rather than their laptop. Anyhow, cheers - interesting article.

By afkrotch on 5/24/2010 11:28:48 PM , Rating: 2
Think he might have meant netbooks. Although many notebooks fall into the $500 range.

Also, it's a blog. Don't think there's any reason why he can't talk among his peers. There's no set rules on such.

By Jansen on 5/24/2010 6:43:02 PM , Rating: 6
In this instance they could of designed an exterior frame type system where you slot in your own HDD and SDD and RAM (if we want the proper hybrid) with attached controllers/etc on a seperate board.

They did. It's called a computer.

By Reclaimer77 on 5/24/2010 9:09:01 PM , Rating: 2
In this instance they could of designed an exterior frame type system where you slot in your own HDD and SDD and RAM (if we want the proper hybrid) with attached controllers/etc on a seperate board.

Glossing over how retarded that would be, you are describing something that then every case manufacturer, motherboard maker, and hardware manufacturer would then have to account for in their form factors. Just so we can have a HD that STILL get's destroyed by any SSD on the market?

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