Seagate has just launched the Seagate Momentus XT, a 2.5” HDD (hard disk drive) that comes with a twist: Seagate claims that it can be as fast as an SSD (solid state drive) “in the real world”. First, why would it be so fast, and how did they manage to do that?

You may have guessed: the Seagate Momentus XT does come with a small amount of Flash memory, so in a way, it is a hybrid HDD/SSD drive. This is not new, but the this time Seagate has improved how it manages the 8GB of Flash memory present in the 750GB Seagate Momentus XT that we have in the lab. This new Flash management technology is called Fast Factor Management and Flash Factor boot.

Why is it fast?

Here’s how it works: the boot files are *always* stored in Flash memory and I don’t think that this should ever take more than 4GB. Secondly, the drive will learn (from your usage) which files are better of being stored in the remaining Flash memory. Finally, it’s all done inside the drive itself. There are no drivers or special software to install.

Because of its hybrid nature, the Seagate Momentus XT cannot really beat “pure” SSDs in sheer performance, because it will sometime use its mechanical HDD part. However, what it can do is to get a great “bang for the buck” if you take into account price, capacity and speed.

This is very attractive because most users often hit system files and a small number of apps on a regular basis. Beyond that, many file accesses here and there are not always worth paying extra for the SSD guaranteed access time and write speed. In short, the Seagate Momentus XT is fast where it matters the most.


And this shows in the tests: the Seagate Momentus XT can take on our Western Digital Velociraptor 10k rpm 300GB which was reserved for rich enthusiasts or enterprise applications not so long ago. Now, you can get comparable or better performance (on average) in a laptop. Typically, the Velociraptor still wins in terms of average seek time, but the Seagate Momentus XT wins everytime it hits the Flash memory, while it loses when it falls back on the mechanical HDD. Both hit close to 200MB/sec in burst mode in an HD tune Pro test.

Seagate has been talking about their super-fast boot time, and that claim is true: because the boot files are effectively stored in the Flash memory of the Seagate Momentus XT, effectively becomes an SSD during boot sequences and therefore performs like… an SSD drive. There maybe a second or two of difference (out of 20-23 sec), but for practical purposes, it feels the same.


It’s been interesting to see Seagate refine its hybrid SSD drives and improve upon the software aspect of things. The Seagate momentus XT is the perfect answer to the speed vs capacity problem that a huge computing population has, namely “they want it all”: capacity, small form factor (2.5” for laptop) and speed. This disk is one of the best solution for that particular challenge, and laptop buyers who want large capacity drives should actually be demanding a Seagate momentus XT from their OEMs.

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