If it's affordable four-bay NAS storage you seek, QNAP has two new models to add to your shortlist. The QNAP TS-420 and TS-421 take the familiar and sturdy QNAP metal chassis, with only minimal trimming in internal specifications to hit budget.

Starting with the TS-420 there's a 1.6 GHz Marvel ARM processor, single-core, with 512 MB of DDR3 memory.

Next up and tested here is the QNAP TS-421 with 2.0 GHz Marvell chip and 1 GB of memory. The rest of the layout is essentially unchanged since the TS-419P II we reviewed two years ago; the two new models can be seen as lite and maxi versions of the same NAS.

Both models have the same chassis, with several useful ports for expansion – two eSATA, two USB 2.0 and two USB 3.0. One v2.0 port faces the front for quick data dumps, configurable for one-touch copy in either direction. Again we have two gigabit ethernet ports at the back where the second could prove handy in more elaborate networks.

QNAP TS-421 review

What has changed remarkably since our last QNAP review is the new QTS 4.0 operating system that now drives the company's network-attached storage. After many years with the same administrator's layout featuring sidebar and graphical if flat look, QNAP has entirely revamped the interface.

It now follows very closely that of arch-rival Synology – a rich and layered environment with movable windows that is, to all intents, the GUI over a multi-tasking workstation computer.

Control Panel is the central focus for most of the drive's settings and adjustments, with additional shortcuts to specific applications provided as cuddly icons on the NAS PC's desktop.

Here you'll find handy collections of utilities like Backup Station, which combines access to rsync incremental backups UNIX-style with real-time remote replication (RTRR) with Apple Time Machine for local Mac automated backups.

On the cloudier front there are shortcuts to Amazon S3, ElephantDrive and Synform. Or you can create backup jobs to direct-connected external disks.

There's even a slide-out graphical tray, just like Synology's, with a quick overview of the system's current status.

The overall look is perhaps a little too bouncy and effervescent for our taste, as if QNAP was trying to outdo Synology by adding more eye candy that ultimately detracts from what is still a serious and powerful operating system beneath the bugglegum skin.

Take Qsync, for example, an application that has matured into a sophisticated yet simple to use utility to provide you personal cloud storage with synchronisation even when roaming on remote networks. It supports selective sync of folders on your Windows PC or Mac, so you don't have to locally store the same full directory as other users, and with privileges control to resolve conflicts on shared files.

QNAP TS-421: Performance

Read performance for a single sequential transfer was at the gigabit limit. We loaded the TS-421 with four WD Red 3 TB disks, and could easily copy files from the NAS at 112 MB/s over AFP.

Write speed was considerably behind though, as we usually find with low-power ARM-powered NAS units. Here we measured just 36 MB/s in large-file sequential writes, around the same speed as USB 2.0. Over SMB the write speed was seen to rise to 39 MB/s; but then reads using the Microsoft network protocol fell to just 72 MB/s.

Power consumption is relatively low, specified at 13 W with system alive but disks sleeping, rising to a typical in-use figure of 31 W. Compared to Intel-powered NAS drives, there's little concern here about excessive power consumption.


The QNAP TS-421 has broad reach across a number of services beside local network file serving, with powerful small-business services as well as plenty of potential for home multimedia hosting. Available for less than £400, this well-made four-bay NAS unit is a recommended product.