In practice, I could only stream real-time-transcoded files to mobile devices at lower resolutions — 480p or lower — and not always successfully. On the other hand, straight DLNA streaming worked perfectly (thanks to a wide selection of very competent players on all platforms), and offline transcoding to MP4 worked great. If you deal with a lot of video, it's quite nice to offload re-encoding tasks to your NAS box. You can have the module spit out 240p, 320p, 480p, 720p, or 1080p versions of your files (or any combination thereof). After you get a feel for the maximum you can stream successfully, you can go with that resolution. The TS-251 also supports Plex and AirPlay.
Running a VM worked a whole lot better than the on-the-fly encoding. QNAP's Virtualization Station is very similar to using VMWare or VirtualBox, except that you're using it remotely via a Web browser Most of my VMs are in VirtualBox format, and Virtualization Station supports only OVA/OVF (open virtual format) and QVM, so I created a Windows 7 VM from scratch.
In my tests, the Windows 7 VM operated just fine using both the HTML5 and Java consoles, albeit not nearly as quickly as it would on a local PC. Still, having the ability to access a VM from anywhere on the planet (assuming you've enabled remote access to the TS-251) and know that any data you save with it will be safe at home on your trusty NAS box is quite cool. The TS-251 uses considerably less power than most PCs.
As noted above, the $499 TS-251 ships with only 1GB of system memory, which is not enough to run Virtualization Station. Upgrading requires removing the shell (hint: remove the drives first) as well as the drive cage, so upgrades aren't for the technophobic. A better suggestion is to wait for the $559, 4GB version, which is coming soon.
Camera licenses are another QNAP gotcha: Surveillance Station comes with two, but Surveillance Station Pro includes only one. You can't set up a large-scale camera system with either without purchasing more licenses at $55 a pop. To be fair, QNAP is hardly alone in this practice: Synology and EMC/Iomega play the same game. Still, it pays to peruse the fine print when you spot a QNAP feature you must have.
The TS-251 is a fast, capable NAS box. It's expensive — and you'll need to add memory to take full advantage of its capabilities — but considering you can host your website and email, control video cameras, stream multimedia, and perform a passel of other tasks beyond serving files, it's a bargain for anyone who can exploit its capabilities.
This is not the box to buy if you're just looking for basic network storage and streaming — there are plenty of less-expensive alternatives.
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