Move /usr to another partition

mount /dev/sdX /mnt # where X is a number of new partition
rsync -rltpHEADXog /usr/* /mnt/
mv /usr /usr.old
mkdir /usr
echo «/dev/sdX /usr ext4 rw,nodev,commit=0 0 0»
mount -a
ls /usr
# check that /usr was mounted successfully
reboot
if everythin is ok, then
rm -rf /usr.old