If you need a process to survive your logging out of the system (or being knocked off of it), you can either screen it or wrap it with nohup. If you nohup, you'll lose control of it entirely, but the output will be written to nohup.out. With screen you can re-attach and take control later:

# nohup program -opts args &

-or-

# screen (press 'ctrl+a d' to detach after you've run the proc)