QNAP TS-251

There's a tremendous range of prices and capacities available in the NAS (network attached storage) field, and a big part of my job as a reviewer is sorting out the balance of performance, features, and price. It's rare for a NAS device to ace all three categories, but QNAP's TS-251 NAS ($409) comes closer than just about any two-bay SOHO NAS I've tested. This dual-drive NAS offers excellent read/write performance, solid fault tolerance, and a sweet set of features, all of which make it a multimedia content storage star for home or small office networks. You will notice some performance hits with certain processor-intensive tasks such as RAID rebuilds, due to its inexpensive Celeron CPU. That's a worthwhile tradeoff, however, as the processor keeps the price fairly low.

Specs and Design
There are two models available: The TS-251-4G, which ships with 4GB of RAM (reviewed here), and the TS-251 model, which has 1GB of RAM. Both have 512MB of flash memory and ship diskless, which helps account for the low price. The drives accommodate two hot-swappable 3.5-inch or 2.5-inch SATA drives or SSDs (up to 6TB of storage). The SSD support makes the TS-251 a better storage deal than the Asustor AS-602T ($579), which has just 1GB of RAM, also ships diskless, and does not support SSDs.

You also get dual Gigabit Ethernet ports—uncommon in a NAS at this price—for link aggregation and redundancy, along with two USB 2.0 ports and two USB 3.0 ports. These ports support printers, external drives, and UPS devices, for example. QNAP also includes an HDMI port so you can attach the drive to an HDTV. The front panel has a one-touch copy button and for physical security, there's a Kensington Security Slot, a small hole to which you can connect an anti-theft lock and cable.

The TS-251 is remarkably affordable for what it offers; one of the few places where its low cost shows is in the rather cheap-looking white plastic housing (like DROBO B810N ). Just keeping the device on my desk for a few days and moving it around a bit during my testing has left it looking a bit beat-up. QNAP's design is nowhere near the attractive, durable, metallic design of the Asustor AS-602T. I even like the Asustor's sturdy drive bays better than the flimsy plastic ones in the TS-251. But, again, the TS-251 is an inexpensive option, and it's reasonable that its design is not as slick as that of more expensive models.

Features and Interface


One of the standout features is multimedia versatility. Thanks to the aforementioned HDMI port on the rear panel, you can play 1080p videos with surround sound from the NAS to an HDTV. The drive also supports on-the-fly and offline HD video transcoding, as well as DLNA and AirPlay streaming. There are also a number of apps within the interface to enhance your digital entertainment including XBMC and Plex Media Server.

I did encounter one issue when trying to open the Digital TV Station app, which purportedly works with a DVB-T USB TV tuner for watching and recording digital TV. I received an error message stating, "Page not found or the Web server is currently unavailable." QNAP representatives told me this feature is not supported in the United States. An error message that explains the feature isn't available would be better, to prevent people from wasting time trying to troubleshoot the problem.

Although the consumer features are the highlights of this NAS, one of my favorite functionalities is virtualization, which will be of more interest to power users and small business owners. Within the interface's Virtualization Station you can create, import, and export Virtual Machines (VMs). If you need to run an app for business use on a specific platform, you can create a VM, and there's no need to buy additional hardware. The VM marketplace expands the TS-251 into an SMB storage solution.

There are even preconfigured templates from which VMs can be created for Linux, UNIX, and Windows. I was able to download virtual appliances from the VM marketplace, which includes apps from VMware. There are virtual appliances for many business tasks including telephony from Avaya, security solutions from Barracuda, document management systems, and much more.


What I especially like about these virtual appliances is that they are portable and can be exported as .qvm or .ovf files and moved to another virtualization platform such as VirtualBox or VMware, providing platform flexibility for businesses as their needs grow.

Remote access to the NAS and its contents occurs via the CloudLink feature and the myQNAP cloud service. I love that remote access does not require any fiddling around with a router or port forwarding.

As with most NAS boxes in his category, the TS-251 supports the SMB/CIFS, AFP, and NFS file systems used by Windows, Mac, and Linux. It also offers now-standard NAS features such as antivirus, backup, and sync, along with IP camera surveillance features.

Performance and Drive Recovery
To test drive speed, I performed a simple 1.48GB file between a Windows 7 laptop and the TS-251 connected to the same switch. The read and write speeds of the file operation were both 113MBps—the fastest I've seen from a two-bay NAS, just edging out the 108MBps of the previous performance champ, the Asustor AS-602T.


The TS-251 I received for testing was configured with RAID 1 mirroring. Since it's hot-swappable, I pulled a drive from the second bay to see how well the system could recover from a simulated drive failure. After a few seconds, the NAS beeped, and I saw pop-up windows stating "Host Drive 2 plugged out" and "Error Host Drive 2 failed." I also went into Disk Manager and saw the RAID status as "Degraded." These are all alarms and notifications I want to see in the event of drive failure.

The other thing I test is how well the NAS can rebuild its RAID array. I replaced the pulled 3GB Seagate SATA drive with a 4GB Seagate drive. After a few seconds the NAS beeped again. I went into the Disk Manager and checked the RAID group. I was happy to see the status marked as "rebuilding." The rebuild process was very slow, however, especially considering I had very little data on the drive. In fact, it took several minutes for the progress bar to indicate that the rebuild was even starting. I attribute this sluggishness to the Celeron processor. I've seen faster rebuilds with newer Intel Atom chips in other two-bay NASes' such as the Asustor AS-602T. It's a poky process, but volume recovery and RAID rebuild does work, and it's likely not something you'll have to do often.

Inexpensive Excellence
I recommend the TS-251. It's a top-performing NAS at a bargain price. You'll notice some sluggishness on processor-intensive tasks like RAID rebuilds, but the unit is a speedy performer on the tasks that you'll be tackling on a daily basis, and that's far more important. The QNAP TS-251 gets our Editors' Choice nod for Consumer/SOHO NASes. For more information on how to choose the right NAS, consult our NAS buying guide.