ASUSTOR AS-604T NAS Network Storage Server Review


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Technology Details: ASUSTOR AS-604T NAS Server

The ASUSTOR AS-604T uses one of the most powerful Intel Atom Dual-Core CPUs based on 32nm fabrication technology, the D2700. Introduced in Q3 of 2011, the D2700 operates at the highest available clock frequency of the Atom family of CPUs, 2.13 GHz. It’s a dual core unit, and it supports Hyper-Threading on its two physical cores. Observing the CPU usage chart during operations, I saw all four (virtual) cores being used concurrently, so the Linux-based operating system has no problems taking advantage of multiple cores and processing threads. The integrated graphics controller runs at the faster clock speed of 640 MHz, which normally wouldn’t be important for a NAS, but the ASUSTOR family of NAS models allows direct streaming of HD video, so the increased performance 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. While the D2700 is going EOL in September of this year, there is plenty of stock available to keep making ASUSTOR NAS towers for a while.


The biggest chip on the board is actually not the CPU; it’s the SATA interface/ RAID controller chip. 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. ASUSTOR took the unusual approach of not using the SATA ports on the ICH10R to interface with the HDDs in the drive bays, instead using them only for the eSATA connections on the back panel. The 4x hard drives in the front of the NAS are managed by Marvell 6Gb/s controllers that are connected to the ICH10R by PCI Express lanes. I suspect they did it this way, in order to have a consistent architecture that was scalable to larger units, with more drive bays. Plus, there’s the side benefit of the 6Gb/s interface that isn’t available from the ICH10R. Not that you’ll notice any difference with mechanical hard drives….


Besides the CPU and ICH chips, the two most important bits of silicon on any NAS have to be the NICs and the SATA controllers. Those are the two endpoints for the entire device, and everything has to pass through one or both of them. The two Gigabit Ethernet controllers are supplied by Broadcom and they incorporate both Media Access Control (MAC) and a Physical Layer (PHY) port. Each BCM57781 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. Broadcom is one of the premier suppliers of NICs and switching products to the enterprise market, so it’s no surprise that ASUSTOR picked them for their brand new NAS line. I’ll share some network throughput graphs later that will show just how good these NICs are.


Marvell supplies the SATA 6Gb/s Host Controllers, two 88SE9125 ICs that each support two 6 Gb/s SATA interface ports and a one-lane 5.0 Gb/s PCIe host interface back to the motherboard. There is a whole family of parts in this series, and this one is optimized for use with a central RAID controller on the system board. In this case the ICH10R provides both the logic behind the RAID functions and the PCI Express lanes that connect to the Marvell SATA controllers.


The ASUSTOR AS-604T is unusual in its support for a dedicated HDMI display output that is driven entirely by the NAS. Intel recently released a new 64-bit driver for multimedia support, and only a few vendors have followed up with software that allows direct connection from the NAS to a HDTV. It’s a real bonus for supporting streaming video and other multimedia, if you decide to use your NAS for content delivery in addition to basic 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 D2700 has an Intel Graphics Media Accelerator 3650 integrated on it that can handle dual displays, but still needs the extra chip to handle HDMI. One other welcome addition to this NAS is USB 3.0. Renesas Electronics (nee NEC) provides their ubiquitous D720200 chip for USB 3.0 duties. I can’t remember the last time I saw any other chip being used for this function.


1GB of DDR3-1333 memory is supplied as standard on the ASUSTOR AS-604T; it’s carried on the SO-DIMM form factor and is addressed by the CPU in Single-Channel mode. The Atom D2700 CPU can support up to 4 GB of DRAM, and with the 1GB DIMM already installed in Slot zero, the AS-604T is currently limited to running a total of 3GB of memory. If you void the warranty by breaking into the chassis and replacing the supplied DRAM with a 2GB part, I’m not sure whether the system BIOS will support the rogue upgrade or not. The single SO-DIMM in my sample was supplied by ADATA and is rated for DDR3-1333 with timings of 9-9-9 for CL-tRCD-tRP. The CPU is limited to 1066 DRAM speeds, so the DDR3-1333 modules are operating well within their limits.


Last, but not least is the Flash memory implemented as a Disk-On-Module (DOM) device, which is 512 M of SLC-based NAND sourced from local Taiwanese manufacturer ADATA. Serving up a Linux-based operating system to an Atom CPU is the dog’s life for a flash memory chip; this module never breaks a sweat.


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 ASUSTOR AS-604T first booted up with one WD 750 Black HDD installed, it idled at 25W. Read operations pulled only a few watts more – 29W, and Writes took an even 30W, with one disk. With all four drives installed, spinning up the platters drew 110W for about a second, and then it settled down to 44W at idle. The AS-604T drew 48W during Read operations with the full complement of disks installed; Writes drew 51W. When the ½ hour timer kicked in and the drives were powered down, the power consumption went down to 26W. In full Sleep mode it went all the way down to a measured 1W. I say “measured” because the P4460 power meter isn’t accurate down at the 1-2W level. So the best I can say is that the 1.4W claim that ASUSTOR makes for sleep mode power consumption is certainly within reason.

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 ASUSTOR AS-604T. 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 much more than that.


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