|Thecus N5550 NAS Network Storage Server|
|Reviews - Featured Reviews: Network|
|Written by Bruce Normann|
|Monday, 24 September 2012|
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Technology Details: Thecus N5550 NAS Server
The N5550 uses one of the most recently released Intel Atom Dual-Core CPUs based on 32nm fabrication technology, the D2550. Introduced in March of 2012, the D2550 is a cross between the D2500 and D2700 processors, operating at the lower clock frequency of 1.86 GHz, but supporting Hyper-Threading on its two physical cores. The integrated graphics controller runs at the faster clock speed of 640 MHz, which normally wouldn't be important for a NAS, but Thecus allows direct streaming of HD video from the N5550, so it does come in handy. Lastly, the 1MB Intel Smart Cache and the integrated memory controller that supports DDR3-1066 DRAM are both performance enhancing features that are at the forefront of what's available in low power computing these days. With the D2700 going EOL in September of this year, the D2550 is the crown prince of the Atom family at the moment.
The biggest chip on the board is actually not the CPU, it's the SATA interface/ RAID controller chip. Thecus surprised me by using a SATA controller that's ubiquitous in the PC world, but almost never heard from in the NAS environment. Intel's ICH10R is perhaps one of the most widely used RAID controllers in x86 PCs, just because it was attached as the Southbridge to several generations of high-end Intel CPUs since it debuted in 2008. Short of doing a full blown custom ASIC, it's hard to beat the performance of this mainstream solution, which was developed back when the most common way of increasing disk throughput was to RAID several HDDs together. Today's Southbridges (err.... Platform Hub Controllers) are rightly judged more by their ability to squeeze the utmost performance out of the latest SSDs, but the ICH10R served admirably during the transition period between high speed spindles and flash memory. There is a widespread understanding that the ICH10R has an upper limit of about 660 MB/s on its aggregate of SATA interfaces, but that's of no importance when the system's I/O bandwidth is constrained by a pair of Gigabit Ethernet ports on the back panel of the NAS.
The Thecus N5550 is unusual in its support for dedicated display outputs that are driven entirely by the NAS. Intel recently released a new 64-bit driver for multimedia support, and Thecus followed it up with a new Local Display software module that allows direct connection from the NAS to HDTV. It's a real bonus for both administration tasks, and for supporting streaming video and other multimedia, if you decide to use it for content delivery in addition to storage. In order to do that, some extra chips are needed that you typically don't see deployed on a NAS. The Chrontel CH7318C is a high speed HDMI level shifter that converts low-swing AC coupled differential input to an HDMI 1.3 compliant output. The Intel Atom D2550 has an Intel Graphics Media Accelerator 3650 integrated on it that can handle dual displays, but still needs the extra chip to handle HDMI. Despite the graphical inference in the firm's name, the Silicon Image Sil3132 chip just provides an interface from 1x PCIe on the ICH10R Southbridge to the single eSATA port on the rear panel. The Sil3132 supports two eSATA ports, so future models may support dual eSATA connections.
The two Gigabit Ethernet controllers are supplied by Intel and they incorporate both Media Access Control (MAC) and a Physical Layer (PHY) port. Each WG82574L chip supports one Ethernet jack on the rear panel, and connects to the rest of the system by an x1 PCIe Rev. 1.1 interface. There is a 40kB buffer on-board to smooth out data transfers by buffering complete packets before transmitting them. Intel is one of the premier suppliers of NICs to the enterprise market, so it's not a big surprise that many NAS vendors tend to choose their products for implementing integrated GbE interfaces. Renesas Electronics (nee NEC) provides their ubiquitous D720200F1 chip for USB 3.0 duties. I can't remember the last time I saw any other chip being used for USB 3.0. Sound duties are supported by a Realtek ALC262, a basic soundcard chip that doesn't have a whole lot to do here, except when using the NAS as a multimedia streaming device. Only 2-channel audio is supported here, nothing like 5.1 or 7.1 is available, if you need the full home theater experience.
2 GB of DDR3-1066 memory is standard on the Thecus N5550; it's carried on the SO-DIMM form factor and is addressed by the CPU in Single-Channel mode. The Atom D2550 CPU can support up to 4 GB of DRAM, but it's unclear if the N5550 can support a memory upgrade or not. There are two SO-DIMM sockets on the motherboard and only one module supplied, but the BIOS is the key as to whether an upgrade will work or not. The single SO-DIMM in my sample was supplied by Transcend and is rated for DDR3-1333 with timings of 9-9-9 for CL-tRCD-tRP. The eight SDRAM chips themselves are from SpecTek, which is a division of Micron Technology.
Last, but not least is the Flash memory implemented as a Disk-On-Module (DOM) device, which is 1 GB of SLC-based NAND sourced from local Taiwanese manufacturer Afaya. Serving up a Linux-based operating system to a 1.86 GHz Atom CPU is the dog's life for a flash memory chip; this module never breaks a sweat. Right next to the DOM location is an empty mini-PCI Express slot. No word from Thecus on what it's typically used for, but the most common devices available in that form factor are SSD modules and wireless Ethernet cards. I'd love to see something similar to Intel's Smart Response Technology implemented in a NAS; that's something that more and more high-end storage vendors are starting to roll out in their data center-class storage systems. Virtualized server infrastructures are pushing the storage systems harder and harder, every year. OTOH, a Wi-Fi module is a whole lot easier to implement on this Intel Atom platform, so that's probably what this slot will get used for, first.
To measure isolated NAS power consumption, Benchmark Reviews uses the Kill-A-Watt EZ (model P4460) power meter made by P3 International. Obviously, power consumption is going to depend heavily on the number and type of drives that are installed. The power draw also depends on the fan speed that's required to keep the drives cool. When the Thecus N5550 first boots up, it peaked briefly at 120 W, and then ramped down to a narrow range of 48 W to 54 W. Once the system completes its boot process, and gets into normal operating mode, it settled in at about 53 watts of power consumption. With all four drives installed and during Write operations, it drew 58W; Read operations drew hardly more than idle. When the ½ hour sleep timer kicked in and the drives were powered down, the power consumption went down to 33W. When the unit is turned off, it still consumes 2W in Vampire mode; be aware that even when it's turned off, the integral 200W SMPS still pulls a small amount of power.
We've seen the ins and outs of the hardware, and the technology under the hood; now let's take a quick look through the list of features that you get with the Thecus N5550. The next couple of sections are kind of long, but it's critical to understand what features you get with these units, and what you don't. It's not just a box full of drives; it's capable of more than that.