I have to say tech support is very lacking of late. I had emailed support telling them my model of Qnap (TS-439), and that I wanted to upgrade to the WD Red 6TB drives, and would it work. I was told yes, however, I could only access 16TB of space. Turns out tech support was WRONG. I can only access 6TB of space out of the 24TB (4 x 6TB = 22TB formatted). And of course, the hard drives can not be returned. I am very disappointed with the untimely responses from tech support, and the bad information.