|QNAP TS-879U-RP NAS Network Storage Rack Server|
|Reviews - Featured Reviews: Network|
|Written by Bruce Normann|
|Tuesday, 07 February 2012|
Page 5 of 16
Insider Details: QNAP TS-879U-RP Turbo NAS
The top cover is easily removed once two thumb screws on the back panel are taken care of. The modular layout is quite evident; the main board takes up a large part of the total footprint. The drive bays at the front of the unit use almost the same amount of space, just more rectangular, and the power supply area is a smaller, but still significant part of the overall arrangement. I pulled the fan package out for this image, to show the full scope of the main PCB. Some things to look for, that we'll see in more detail as we continue the tear down, are: the memory slots, the two x8 PCI Express slots, the DOM memory board, and the two heatsinks showing the locations of the Sandy Bridge CPU and PCH (Platform Controller Hub, nee Southbridge).
From this angle you can see the size of the CPU heatsink a little better, and the fan module is installed in this image, as well. Each of the three fans is a San Ace 60mm unit from premium maker Sanyo Denki, that's 38mm thick and PWM controlled. They are designed to handle higher backpressure than a typical PC case fan sees, both because of the layout of the device and the fact that it may run 24/7 for years without anyone cleaning it. Because cooling is such an important element of the overall reliability for devices like this, there's no good excuse for failing to clean things on a regular basis, especially since the modular fan assembly is designed to be quickly and easily removed and replaced. There's even a warning sticker on the fans that tells you exactly how long you can expect the NAS to run without it, just in case some technician thinks he can take it out for cleaning right before his lunch break. The electronics obviously need their fair share of cooling, but with up to eight HDDs crammed into a tight space, there is a great need to keep them cool, as well. Hard drive life is closely linked to operating temperature, and drive life is definitely something that most users of this unit will be concerned about.
Near the middle of the TS-879U-RP, the main board ends, and several PCI-e edge connectors transfer the signals to a vertical board that serves as the backplane for all the SATA HDD connectors. It's not just a passive board, there are drive controller ICs and a significant FPGA chip located on the backplane. This is consistent with how QNAP builds their larger tower models, putting the controllers closer to the drives they are responsible for. Each Marvell 88SE9125 SATA controller chip handles two drives, so the board isn't littered with these chips, but they're easy enough to spot. There's a fairly large open space above the drive bays that is home to a small board for driving the display and the front panel controls. On the 12 bay TS-1279U-RP, which shares a similar chassis, this space would be filled with drives. It's not only the chassis that's similar; the main PC board is silk-screened with a TS-1279 designation. There are a couple of empty solder pads where a third instance of a controller IC would probably be installed, were this board built up to the full TS-1279 specs.
Here's something you don't see every day on a NAS server: x8 PCI Express slots, two of them. This is where you have to go if you want to get the full performance that the TS-879U-RP is capable of. Plain old 1000BASE-T limits throughput to about 120 MB/s, and the potential is there for way over 1000 MB/s in this model. You really only need one of these PCIe slots, since most 10GbE NICs come in a dual-port configuration, but products of this caliber need to have some degree of future-proofing built into them. Right next to the expansion slots is the dual-redundant 512MB Disk-On-Module (DOM) PC board which contains two complete, independent operating systems. If one OS fails, the system reboots with the spare OS, and then immediately starts to repair and rebuild the OS on the corrupted module. All this takes place automatically, without user input.
The memory controller is integrated on the Intel Sandy Bridge CPU, and it is designed to handle DDR3-1066 and 1333 memory modules in its native configuration. The QNAP TS-879U-RP comes standard with 2GB of ADATA DDR3-1333 CL9 memory, which is installed in one of two DIMM sockets located on the main board. The specs for the TS-879U-RP call out a maximum memory capacity of 4 GB, but users have reported success with installing two 4GB DIMMS, and running with 8GB of system memory. Based on my testing, these folks must be running some of the more challenging apps on their boxes, because straight data transfers use very little of the NAS memory capacity.
The latches on the socket where the factory memory was installed are firmly held closed by a nylon wire tie, installed during the system build. At first I thought it was some sort of anti-tamper measure, but I think it's really there to make sure the memory module doesn't get loose. There's actually a lot of vibration in data center racks, mostly due to hard drives and cooling fans, so it makes sense to tie everything down. Airplanes also have a lot of vibration, and I can tell you from experience shipping machinery to Japan, that things WILL loosen up over the course of a trans-oceanic plane ride.
So far we've had a good look at what there is to observe as far as hardware goes, but let's dig down one more layer, down to the chip level where the technology really starts to get interesting. I love my hardware just as much as the next person, but it's only half the story....