QNAP TS-421 & QTS 4.0 Review 3

QNAP TS-421 & QTS 4.0 Review



We would like to thank QNAP for supplying the review sample.

QNAP is a key player in the NAS market, and after many years of sticking to the simple but highly usable interface of the proprietary operating system for their products, they decided to upgrade to something more elegant, more appropriate to our times, with icons and lots of customization options. Their new operating system, the QTS 4.0, can easily be called a major upgrade of the older one. Offering many interesting features that will thrill most users, it makes QNAP’s products even more competitive as the QTS 4.0 is a multi-windowed, multi-tasking OS with a nice GUI resembling that of modern smartphones (IOS, Android). It is also highly customizable, allowing you to install dozens of applications to make your NAS server suit your needs. More about the QTS 4.0 can be found here. We will also take a rigorous look at it in the following review, so you had better read all or most of this review--don't skip to the conclusion!

The NAS server and our vessel for our trip into the QTS 4.0 world is the TS-421, a mid-level unit primarily for home and SOHO environments. It doesn't cost a ton but can't be called mainstream either, especially if you add the value of the four HDDs it needs to be fully operational. It makes use of a Marvell CPU that runs at 2 GHz and comes with 1 GB of DDR3 memory installed, allowing it to easily cope with most tasks. However, it doesn't have an HDMI port like the higher-end models, so it can't play the role of a media player too, but that may not be as important to most buyers. It does, after all, support DLNA streaming, which will allow you to watch its multimedia content on any compatible device. But enough has been said--time to start the review!


QNAP TS-421 Specifications
ProcessorMarvell ARM 88F6282, single core, 2.0 GHz
Operating SystemEmbedded Linux
Memory1 GB DDR3
Storage4x 3.5"/2.5" SATA II
RAID Levels:Single Disk, JBOD,
RAID 0, 1, 5,
5 + Hot Spare, 6, 6 + Hot Spare, 10, 10 + Hot Spare
Capacityup to 16 TB (disks not included)
iSCSITarget & Initiator
Networking2x 10/100/1000 Mbit Ethernet
Additional Connectors2x USB 2.0, 2x USB 3.0, 2x eSATA
Dimensions 177(H) x 180(W) x 235(D) mm
6.97(H) x 7.09(W) x 9.25(D) inch
Weight 3 kg
Power ConsumptionSleep: 13 W
In operation: 26 W (with 4 x 500GB HDD installed)
Power SupplyExternal, 96 W, 100-240 V
Fan 1x 90 mm
Warranty2 years
Price excluding VAT
(at the time of the review)


The TS-421 uses the same CPU as the older TS-419P II we reviewed in the past. The two NAS servers are nearly identical hardware-wise. The only difference is the 1 GB of RAM the first is equipped with. The Marvel CPU only has one core and is much weaker than even the dual-core Atom CPUs higher-end QNAP NAS servers use, but the Marvel will be enough for home usage, and the TS-421 has enough RAM for its embedded Linux OS.

Up to four HDDs can be installed, but the newer SATA III protocol is not supported. This is of less significance to mechanical drives as SATA III actually only makes sense with fast SSDs, making it worthless in a NAS because it will most likely be equipped with large mechanical drives (HDDs). SATA III in a NAS sounds more like a marketing gimmick. Before purchasing any drives for it, make sure to take a look at the QNAP HDD compatibility list since some HDDs may not work all that well with this NAS.

For networking, the TS-421 is equipped with two Gigabit ports that can be teamed, doubling network transfer speed. However, you need to have a compatible switch with the Link Aggregation Control Protocol (LACP) to exploit port trunking.

The I/O ports of the TS-421 include two USB 3.0 ports. The ports are very useful in a NAS since they make fast transfers to compatible external storage devices possible. Two eSATA ports are also bundled.

The dimensions of the NAS are pretty compact and its net weight is low, so you can easily move it around when needed. Its power consumption is also minimal, allowing for 24/7 operation without any worries about increasing the electrical bill. This is the main advantage of such NAS servers as compared to custom-made PC/NAS systems. The latter consume significantly more. A few more watts may look insignificant, but you have to factor out the difference over the long run, after months or even years of 24/7 operation.

The warranty of the NAS is restricted to only two years, which is unfortunately a common warranty period among NAS manufacturers. The price makes the TS-421 part of the mid-level category.


The NAS comes in a large, sturdy package that offers adequate protection. The front has a photo of the NAS with the LCD screen in the middle. The model number and what this unit is capable of are depicted at the top of the front, against a blue backdrop.

This side gives a glimpse of the interface that the fresh operating system provides. Also, a series of icons depict the basic applications and functions this NAS supports.

This side has a brief, multilingual features list. On the bottom is a useful scheme describing all the buttons, LED indicators, and I/O ports found at the front and back of the NAS.

This side deals with the cloud features of the NAS and with the mobile applications it supports.

Contents & Bundle

Once we opened the top flap of the box, a "thank you" message welcomed us, along with links to QNAP's support and social media pages and the corresponding QR codes. The first thing you will find inside the box is the quick installation guide, which we will examine in detail later. Two large foam spacers protect the unit well. It is also wrapped in plastic.

The accessories box stores all necessary screws for the installation of four HDDs, two Ethernet cables, and the power brick along with the corresponding power cord. No software CD is included since QNAP wants you to download the latest software from their site. This isn't so terrible for a NAS as you will probably already have an internet connection, or you wouldn't buy one in the first place.

The power brick is provided by EDACPOWER, and its model number is EA11351-A-120. It can deliver up to 10 A with 12 VDC output, making 120 W available to the NAS, which is more than enough.


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.

A Look Inside

It's now time to strip the NAS down to discover what components are hidden inside its casing.

As with all QNAP boxes, the break-apart process isn't too complex since the one-piece top and side cover is easily removed by unscrewing only three screws. The casing has enough room to accommodate an SFF PSU, but the TS-421 uses an external brick instead. As you will also find out, the TS-421 is a TS-419P II with more RAM (up to 1024 MB from 512 MB).

The small mainboard is underpopulated, and the most important components on the rear side are two RAM chips. There are two on this and two on the opposite side. A total of 1024 MB of DDR3 RAM (Hynix H5TQ2G83CFR) is directly soldered onto the mainboard. You cannot upgrade the RAM total since there are no DIMM slots.

A single-core Marvell 88F6282 SoC is the brains of the NAS. It is cooled by a small, passive heatsink since its thermal dissipation is low. The CPU this SoC integrates is fully ARMv5TE compliant and is equipped with 256KB of L2 cache.

The Ethernet ports are controlled by two Marvell Alaska 88E1318 ICs. Each of these ICs contains a single Gigabit Ethernet transceiver. It implements the physical Ethernet layer of the 1000BASE-T, 100BASE-TX, and 10BASE-T standards.

The GL850G IC of Genesys Logic is the USB 2.0 hub controller. It provides four downstream USB ports.

This PIC16F690 IC is an 8-bit microcontroller and includes, amongst others, twelve A/D channels and two voltage comparators.

The buzzer of the NAS is quite loud.

The 128 Mb serial flash memory of the NAS (25Q128A).

The single-phase VRM (Voltage Regulation Module) that feeds the PCIe card.

The PCIe card to which all four removable drives attach utilizes a Marvell 88SX7042 controller. It supports the SATA II protocol and not the newer SATA 6 Gbps, but the 88SX7042 surely won't bottleneck the system since non-mechanical drives cannot exceed SATA II limits.

The LCD screen functions are handled by a Microchip PIC16F73 8-bit microcontroller.

As per usual for a QNAP product, the cooling fan is provided by Y.S. Tech. Its model number is FD129225LB (90 mm, 12 V, 0.15 A, 1900 RPM, 40.2 CFM, 80000 MTBF), and it uses ball bearings, which will have it last much longer than a sleeve-bearing fan.
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