lvl 30 ft span

on a 20 x 30 pole barn, 6"x6" post every 10 ft for a total of 8 posts , 3 on each side and 4 across the back, can I have front 30 ft. span open with no posts and what size lvl and how many should I use.Its a basic no walls pole barn with just a 4/12 pitch roof with 2x8 rafters and 2x8 joist on 2ft centers.