A issue with Ultra 4 and 3tb drive

All drives can and do fail. Most will after long service, but many will fail early. (Just as some light bulbs go "pop" when you turn them on the first time). My first NAS a 4+ year old NV+ was initially set up with 2x500GB Seagates. One morning i walked in to only one drive light and checking Frontview, sure enough one drive had failed. I replaced it that day and RMA'd the failed drive. The original drive in the other slot and the replacement for the failed drive ran for over three years accumulating over 25,000 power on hours without any problems. I still have the NV+ in service, but the drive size has been upgraded twice in the last year.

I would suggest you download and install SeaTools for Windows. Then connect the drive to an SATA port on the motherboard and run the tests on that drive. The tests will not run properly if the drive is connected to an eSATA port or USB port via a converter.

FWIW - I am currently running 2x3TB Hitachi drives in two NVX units running 4.2.17. In addition, if the Ultra 4 had trouble with 3TB drives, there would be a lot of previous posts, and I don't recall any off hand.