[arch-general] System manipulation

Hi Folks Found myself with a rather awkward situation my / partition has only got 5% free i need to enlarge it somewhat i have another drive i can throw at the job my question is how do i go about moving "/" to another drive i have looked but cant find an answer i do not really want to do a complete reinstall as i have so much extra software installed some of which has been a real pain to get working . Any help please Pete .