I have the Asrock N3150dc, 4GB, 2 x HD WD 6TD red, 1 x HD 4T red, Raid 5, DSM 5.2-5644 Update 5.
Before the update, but I do not remember the previous revison I had (anyway 5.2-xxxx), everything was working properly. Now the USB3.0 always disconnect any external hard drive (it does not matter if it is supplied by the USB or by external power supply) as soon as I try to copy anything (sometimes it lasts for 1-2GB). This is a software issue and not a hardware related issue (I have also upgraded the power supply from 60 to 90W). The USB2.0 always works fine.
With regards to performance, as