Updated 9/4/2008: Corrected power supply info in Table 1
A post in the forums a few months ago asked what is the highest throughput that a NAS can achieve with a gigabit Ethernet connection. A gigabit connection is theoretically capable of 125 MB/s, but the fastest products we have tested typically run at less than half of that, even in a JBOD configuration. So I decided to start a multi-article series to see how close we can come to gigabit wire-speed performance with a NAS.
The first step was to assemble a test bed for the experiments. Motherboard choice was a little more difficult than I thought, since I wanted an onboard chipset with RAID 5 capability that also had Linux support. I also wanted an onboard gigabit LAN chipset that used PCIe, so that throughput wouldn't be choked by a PCI-based LAN connection. One PCIe x 1 slot was also required, so that I could test the difference between on-board and add-in Ethernet.
I decided to focus on Intel chipsets to start, since they are widely supported and I have been using their PRO/1000 MT gigabit adapters for some time with good results. I also wanted to explore the Matrix storage manager that is used for onboard RAID configuration.
I initially chose a GIGABYTE GA-G33M-S2L motherboard, but was saved by forum reader Madwand. He pointed out that the Gigabyte board's Intel ICH9 South Bridge did not support RAID 5 and instead suggested an ASUS P5E-VM DO (Figure 1).
Figure 1: ASUS P5E-VM DO motherboard
The ASUS board uses an Intel Q35 North Bridge and ICH9DO South Bridge, which supports RAID 0/1/0+1/5. The board also has an Intel 82566DM gigabit Ethernet chipset, which connects via PCIe.
Before I purchased the ASUS board, I contacted Intel to see if they could provide one of their motherboards. There were not able to, but did send a Core 2 Duo E7200 CPU. Intel also provided a few Gigabit CT desktop adapters, which use Intel's 82574L PCIe-based gigabit Ethernet controller.
I also purchased 2 GB of DDR2 800 Corsair memory to go with the motherboard. I got two 1 GB sticks so that I could try 1 and 2 GB memory configurations to see whether more than 1 GB of memory would significantly affect improve performance.
With the motherboard and processor taken care of, I turned to drive selection. I contacted Seagate, who initially wanted to provide Barracuda ES.2 SAS drives. However, even though the cost difference of the SAS drives wasn't that great, I decided to stick, at least initially, to using SATA drives, since that is what most of you out there will be using. Seagate was kind enough to send four Barracuda ST31000340AS drives.
Finally, I needed something to put all of this in but found that choosing a case was harder than I thought it would be. Perhaps foolishly, I tried to find a small case, since I really didn't want the NAS to be in a tower format. However, case manufacturers aren't really catering to NAS builders, because I was able to find only one case that came anywhere near what I was looking for.
Chenbro's ES34069 "Mini Server" Chassis (Figure 2) seemed like an interesting choice at first. But it could take only a Mini-ITX or Mini-DTX motherboard and required an external power supply adapter. So I had to give it a pass.
Figure 2: Chenbro ES34069 Mini Server Chassis
I instead opted to spend as little as possible on the case and chose a Foxconn TLM776-CN300C-02 from NewEgg, but ended up being sorry that I did.
The main reason that I chose the case was its ability to handle six 3.5" drives (Figure 3). The two 5.25" drives bays were a bonus, since I really only needed one for a CD/DVD drive.