Adding Swap Space

Introduction
This guide has worked great with my UNR. Here's a copy and pasted guide (references below)

Steps
Procedure to add a swap file

You need to use dd command to create swapfile. Next you need to use mkswap command to set up a Linux swap area on a device or in a file.

a) Login as the root user

b) Type following command to create 512MB swap file (1024 * 512MB = 524288 block size):


 * 1) dd if=/dev/zero of=/swapfile1 bs=1024 count=524288

c) Set up a Linux swap area:


 * 1) mkswap /swapfile1

d) Activate /swapfile1 swap space immediately:


 * 1) swapon /swapfile1

e) To activate /swapfile1 after Linux system reboot, add entry to /etc/fstab file. Open this file using text editor such as vi:


 * 1) vi /etc/fstab

Append following line:

/swapfile1 swap swap defaults 0 0

So next time Linux comes up after reboot, it enables the new swap file for you automatically.

g) How do I verify swap is activated or not? Simply use free command:

$ free -m

Reference
http://www.cyberciti.biz/faq/linux-add-a-swap-file-howto/