Increase Linux Swap Space dynamically

Imagine this, you start the OUI and your pre installation check fails due to insufficient swap space. Now I agree that you got to check all this before starting the installation but just in case you missed it. You could always increase it on the fly.

Check the memory on your server
# free -m
total used free shared buffers cached
Mem: 8117 3204 4913 0 77 2648
-/+ buffers/cache: 478 7639
Swap: 101 0 101

Now say you need to increase it by 500 MB for your server, first locate a place you can spare this 500 MB in my case i found it in /u01

Use the dd command to create a swapfile
#cd /u01
# dd if=/dev/zero of=swapfile bs=1024 count=512000
512000+0 records in
512000+0 records out

# ls -ltr
drwx------ 2 root root 16384 May 1 2006 lost+found
-rw-r--r-- 1 root root 524288000 Nov 28 13:58 swapfile

Next issue the following two commands
# mkswap swapfile
Setting up swapspace version 1, size = 524283 kB
# swapon swapfile

Now check you memory again
# free -m
total used free shared buffers cached
Mem: 8117 2176 5941 0 45 1975
-/+ buffers/cache: 155 7962
Swap: 601 0 601

Here is your increased SWAP.

To make this change permanent add the line in your etc/fstab
/u01/swapfile swap swap defaults 0 0