It’s a good idea to use two CPU cores to speed up multiple drives in RAID 5 or 6 arrays and it’s even better to increase clock speeds. We put Qnap's TS-559 Pro+ with an Atom D525 dual-core CPU to the test: is it any faster than devices with Atom D510?

For a long time, mass-produced network-attached storage devices have given our readers a mixed impression of what they can do (and why they cost so much, frankly).

The included software often only includes basic functions like network file sharing via SMB/CIFS protocols. Moreover, the data transfer rates for important tasks like writing file backups fall disappointingly in the low double-digit MB/s range. Performance is, to a great degree, dependent on the processor built into the device. And most of the time, those processors are pretty darned anemic.

That's one reason why NAS manufacturers tend to focus on other value adds. Over time, they optimize their respective firmwares, rework the hardware internals (while still abiding by strict thermal and power requirements), and equip them with as many convenience convenience-oriented features as possible. For instance, it's difficult to find a NAS device these days that doesn't function as a media server, as well as a data storage unit, delivering multimedia content via UPnP DLNA. Firmware with integrated Web serving capabilities, including a PHP interpreter and MySQL database, is equally widespread. And there are still other differentiators cropping up all over.

Bear in mind that most of the value-adds tacked onto each vendor's firmware is enabled by adequate processing power. While many devices use ARM- and PowerPC-based processors due to their efficiency (for example, the Synology DS408j, which is based on an 800 MHz Marvell Kirkwood 88F6281 ARM processor and ranked in the top third of our NAS Charts), a significant increase in performance is generally achieved by using Intel's Atom processors.

Historically, most NAS manufacturers used the Atom D510, which is equipped with two cores and runs at a clock speed of 1.66 GHz. This CPU was released in the first quarter of 2010. A further evolution of the Atom processor lineup was presented in the second quarter with the D525 model. This one has the same two cores and four threads (enabled by Hyper-Threading), but runs at 1.8 GHz. Not only does it support DDR2-667/800 memory, but it also accommodates DDR3-800 RAM. The benefit of higher clocks and faster memory support are reasons enough for appliance engineers to rework and refresh their products.

At the end of December 2010, Synology released its DS1511+, based on the Atom D525, while Thecus introduced the N4200 Pro, also using the 1.8 GHz processor. A third popular NAS vendor, Qnap, also has devices using the same generation of low-power processor. It released products ranging from two-bay to eight-bay products, all of them equipped with Intel’s Atom D525 processor, as indicated by the plus in this family's nomenclature.

We were curious whether the "+" would be represented by an increase in data transfer rates. Therefore, we asked for a test sample, which found its way to our lab in the form of a Qnap TS-559 Pro+. Our findings are summarized on the following pages.