If speed is what you're looking for in a two bay NAS enclosure, QNAP's TurboNAS TS-259 Pro+ has speed in spades. This feature-packed unit sports dual gigabit ethernet connections for failover protection and better performance, and supports iSCSI as well. The "Pro" in the moniker here is no joke: This enclosure means business.
The TS-259 Pro+ is a bit old school in appearance with its drive trays in full view (we like that), but it's solidly built compared with much of the competition. It also has the ability to lock the drive trays, a feature aimed at business audiences. The unit has a whopping five USB 2.0 ports for attaching additional storage or a printer (one in the front, four in the back) and a one-touch copy button for quickly transferring the contents of USB drives to its internal storage.
Like competitor Synology, all of QNAP's enclosures run the same operating system, and that OS is every bit as feature-rich as its rival's. QNAP provides DLNA-certified media serving, support for bittorrents, video surveillance, many forms of remote access, extensive backup capabilities including rsync for syncing files with other servers and NAS boxes and much more.
The QNAP OS, accessed via a web browser, lacks Synology's slick windows-in-a-browser interface, but that only places it at a slight disadvantage. Compared with everyone else in the industry, QNAP's OS is light years ahead.
I tested the TS-259 Pro+ with 3TB and 2TB drives installed as one 5TB volume. Even in this mode, the unit is fast. No, make that really fast. In my tests, it averaged approximately 83MBps writing data to its drives, and about 65MBps reading on my gigabit network. The read performance is only a bit better than rival Synology's DS211+, but the rate of putting data onto its own platters is nearly twice as fast.
You pay dearly for the TS-259 Pro+'s speed, but if you regularly back up a lot of data to your NAS box, it's more than worth it. And feature-wise, you can't beat it.