Exterior

As we expect from a QNAP product, the quality of the TS-421 is very high, fully justifying its high price. The chassis is fully metallic and brushed, and all edges are rounded. The design is classic but does easily keep up with today's demands.


The removable HDD trays at the front (or caddies) take up most of the real estate, but the LCD screen on top of them covers a large area of the front's top. Near the bottom-left corner reside the on/off button and the "copy" button, with the latter totally surrounding a USB 2.0 port. We would prefer a faster USB 3.0 port at the front, but the mainboard apparently sets the limitation here.


Four LED indicators can be found under the LCD screen. Four more are installed on top of each tray, providing feedback about the HDDs' operation. The button on the right of the screen allows you to perform several basic administrative tasks, get information about the IP address of the NAS on the network, the system temperature, etc. A small decal on the top also provides information about the sequence of the HDDs.


We shot some photos of the internals with the caddies removed. The PCIe expansion card that holds all SATA ports can clearly be seen, but we will take an even better looks at it after we fully dismantle the unit.


Only one of the two sides features an exhaust grill.


The fan grill covers a significant part of the rear side, and a warranty sticker prevents you from opening the unit up since the RAM of this model cannot be upgraded. We will inevitably have to tamper with the sticker when we take the unit apart.


Above the red eSATA ports is a hole that hides the reset switch.


Like with other multiple-bay NAS, this one too is equipped with two Ethernet ports.


The blue ports are USB 3.0 and the black one is USB 2.0. Below them resides the power input socket.


At the bottom of the NAS are four easily removable plastic stands.


Strangely enough, QNAP forgot to number the caddies this time, so you have to mark them before removal to later figure out which one goes where. All other QNAP products we have tested so far had numbered caddies, so this may be due to a mix-up at the production line. That said, we will mention it as a drawbacks in our conclusion.

All caddies are metallic and of very good quality. They can hold 3.5" and 2.5" disks, and QNAP includes all the necessary screws for both types of disks.