This is said to be the first QTS-Linux dual system NAS geared for the Internet of Things era.
This is something I feel QNAP is doing much better than any of its competitors.
All up, the 4GB TS-853A is currently selling for$965in diskless form on Newegg.

Like all good NAS devices, the TS-x53A series allows drives to be hot-swapped during operation.
The use of individual, detachable 3.5-inch hard drive trays makes adding or removing storage capacity a breeze.
Around back the models do vary, so let me break it down for you.
The two-bay TS-253A features two Gigabit Ethernet ports and a small 70mm cooling fan.
Cooling the TS-853A are a pair of 120mm fans which seem to work well.