Larger than 2TB drive

I have played around with different firmware/linux builds for the SLUG, but I am struggling to get anything that will work with a "Lacie Biggest Quadra" this is a USB RAID enclosure that takes 4 1TB drives and uses RAID 5 to give a total space of around 2.7TB, it has an option of limiting itself to 2TB which works with the SLUG, but I want to use the full 2.7TB. Has anybody had any success with drives larger than 2TB, and if so how did they do it.

Kevin