Is there a kernel parameter I can tweak to allow me to mount more drive space? 2TB is nothing any more (haha).
JFS should work for big file systems. I tested it some time ago with a >10 TB holey loopback file and there were no problems.
In theory there should not be a 2TB limit on block devices for the 64bit kernel, but details depend on your driver etc (i could well imagine drivers not being 64bit clean). We haven't tested if this works in 9.0.
What you could do is to check if the access to the block device works at all. e.g. write some known pattern to the block device and read it again. Do that first with the RAID directly (without LVM) and then with the LV.