Page 3 - A Closer Look - Hardware (Internal)
There is no wasted room inside the QNAP TS-251B network attached storage. We can see two 3.5" drive bays occupying majority of the area as well as the 70mm fan at the back. A centimeter or so of clearance room can be seen between the rear fan and the two hard drive bays. This allows some space between components to reduce heat congestion. At the top is an expansion card slot for QNAP's QM2 PCIe expansion card series, which features two M.2 SSD slots and 10GbE connectivity depending on variant. You can also use it for an AC2600 wireless card. The expansion card slot is native to the system-on-a-chip. Its well-placed rear exhaust fan can then easily take out the warm air and allow cooler air to flow over the mounted hard drives with minimal turbulence noise. A small passive heatsink is used to keep the processor running cool. The motherboard is mounted with its components facing inwards to take advantage of the airflow generated by the sole rear fan as well. Generally speaking, it is pretty packed inside the QNAP TS-251B, but everything is neatly placed and cabled to maximize cooling efficiency.
The power supply is an external brick manufactured by Delta Electronics. The DPS-65VB is a 12V power supply specified for up to 5.417A of current. This means it can deliver a maximum of 65W. As far as efficiency is concerned, it is "VI" rated. To skip over all the nitty gritty compliance details of this technical specification, the basic gist of it is it has to be at least 87.5% efficient in given conditions and consumes less than 0.50W in no-load mode.
The QNAP TS-251B is somewhat straightforward to disassemble, since there were only few screws that holds the QNAP NAS' motherboard to the chassis. It is similar to the TS-253B. Upon closer inspection, we can see only solid state capacitors are used. Behind the small black aluminum heatsink is an Intel Celeron J3355 "Apollo Lake" system-on-a-chip. The 14nm Intel SoC features two cores running at 2.0GHz, Turbo Boost up to 2.5GHz, 2MB L2 cache, and is rated at 10W TDP. An integrated Intel HD Graphics 500 is clocked at 250MHz (700MHz burst) with 12 execution units. Intel's latest integrated graphics solution provides native support for H.265/HEVC decoding. An ITE IT8528E IC provides system monitoring information.
Intel's Celeron J3355 SoC provides native support to both of its USB 3.0 and USB 2.0 as well as SATA 6Gb/s ports. One Gigabit LAN port is powered by Intel's WGI211AT controller. A Realtek ALC262 audio codec handles the 3.5mm output and inputs at the back. All of these mentioned parts are soldered directly to the motherboard. The system firmware is stored on a Toshiba THGBMDG5D1LBAIL 4GB eMMC flash chip.
The user upgradeable memory slots can be seen above. Since this is the front of the motherboard, you can easily swap RAM on the system immediately after taking the shell off, which means you will not void your warranty. Our NAS came with 1x4GB of ADATA DDR3L-1866 double sided SODIMM using Micron D9SGQ ICs. From my experience, I never needed any more memory than my QNAP NAS already came with, but user upgradeable memory is always a good thing for more RAM intensive applications. This is especially useful if you are planning to use it as a virtualization box.
The SATA backplane ports are powered by a controller native to the Intel system on a chip. A built-in speaker gives you voice announcements on system status. Meanwhile, the rear exhaust fan is an Y.S. Tech FD127025MB, which is a 70mm dual ball bearing fan specified at 0.15A for a maximum of speed of 4000 rpm. The rated airflow is 33.1 CFM and 5.0 mm-H2O static pressure at 34.5 dB of noise. This is similar to the one found in the QNAP TS-253B.
Installing hard drives is a straightforward procedure. Since this is a SATA system, all hard drives are hot swappable. Removing the hard drive tray is very simple -- just unlatch the lock at the top and pull it out. The disk trays are not labeled. Functionally, the installation order does not matter in a RAID system, but I think being able to discern which disk is which by a physical label can be very useful. Obviously, you can grab a permanent marker and mark them by hand, but labeling them "Disk 1" and "Disk 2" from the factory is probably not too hard. Each tray can accommodate one 2.5" or 3.5" drive; where the latter can be installed tool-free. The latest trays are made out of plastic instead of metal to prevent any electrical short problems and are not compatible with previous generation QNAP devices. The TS-251B supports single disk, RAID 0 (Disk Striping), RAID 1 (Disk Mirroring), and JBOD (Linear Disk Volume). If you want to encrypt your data, you have the option to enable its AES 256-bit folder-based encryption.
We can see QNAP used excellent hardware for their network attached storage system. But we must understand the sum of the system is not limited to just the hardware, but also the software. Over the years, network attached storage systems have evolved from relatively simple file servers to fully fledged network appliances with more features than I can keep track of. As such, we will take a look at the latest operating system update from the company, QTS 4.3.5. Putting the shell back on, I fired the system up for testing.
1. Introduction, Packaging, Specifications
2. A Closer Look - Hardware (External)
3. A Closer Look - Hardware (Internal)
4. Configuration and User Interface, Part I
5. Configuration and User Interface, Part II
6. Configuration and User Interface, Part III
7. Performance and Power Consumption