add swap space

if you run softwares that require a large amount of memory, you need to add more swap space

You have three options: create a new swap partition, create a new swap file, or extend swap on an existing LVM2 logical volume. It is recommended that you extend an existing logical volume.

https://www.centos.org/docs/5/html/Deployment_Guide-en-US/s1-swap-adding.html