If using a PERC 5/6, 2TB is the maximum physical disks size - it is a hardware limitation, and there is no way to use anything bigger than 2TB. If using a SAS 5/6 in RAID mode, 2TB is the maximum - it is a limitation of its RAID limitation. I would never do this, but some have said that drives larger than 2TB will work on the SAS 5/6 in NON-RAID mode (left unconfigured).
Greetings, I have PowerEdge 2950 server with Six internal hard drive bays. How many maximum hard disk capacity supported in one bay? Thanks for answer and best regards. 
PowerEdge 2950 Maximum Support HDD Capacity