This backplane solved all of my very odd issues with 4TB drives. No one could specifically state the issues with SAS1 and 4TB but I can tell you I had random rebuilds on reboot, a loss of enclosure connectivity, hard hangs and drive errors until I installed this.
Replaced backplane that had developed bad slots, and voila, everything works again! Recommended if your Supermicro SAS2 expander has developed bad slots.