I have many X8DT6-F motherboards. Any boards before April 2011 can work with 3TB drives. After April boards can only work with 2TB drives. Is there any firmware I need to upgrade?
Yes, you need to upgrade your on-board LSI SAS 2008 firmware to PH10 or newer rev.
https://www.supermicro.com/wdl/driver/SAS/LSI/2008/IR/Firmware/PH10.0/