This is how to format swap partition
mkswap /dev/data/swap
shell output:
mkswap: /dev/data/swap: warning: don't erase bootbits sectors
on whole disk. Use -f to force.
Setting up swapspace version 1, size = 104857596 KiB
no label, UUID=48a645a7-18f1-4e51-996f-fd7687e0380c
swapon /dev/data/swap
or
swapon -U 48a645a7-18f1-4e51-996f-fd7687e0380c
Run this to check
free -m
https://help.ubuntu.com/community/SwapFaq http://askubuntu.com/questions/33697/how-do-i-add-a-swap-partition-after-system-installation