Move huge directory on the root partition to a huge non-root parition

Assumption: /mnt is a huge disk partition separate from the / partition  (aka root partition)

1. mkdir -p /mnt/home/myfatdirectory
2. kill all processes that have open files to /home/myfatdirectory
1. lsof /home/myfatdirectory
2. make sure you get ZERO results, ie no processes have open files to this directory
3. mv /home/myfatdirectory /home/myfatdirectory_old 
4. mkdir -p /home/myfatdirectory
5. mount --bind /mnt/home/myfatdirectory /home/myfatdirectory
6. add to bottom of /etc/fstab, so the mount is picked up on reboot
1. /mnt/home/myfatdirectory /home/myfatdirectory none bind 0 0

NOTES:

1. fix perms as necessary by interleaving your own steps into the above
2. for the paranoid: you might want to make sure fstab entries work fine on reboot