Add a Swap File to RHEL/CentOS

Sometimes, due to some new specific server requirements, you will find it necessary to increase your swap space. Even if your swap partition is setup as a Logical Volume, your requirements may exceed what is available. This is where creating a new swap file is the best option. In this example, we are going to add a new 12GB swap file.

Check Current Swap Space

Verify the total amount of used and free physical and swap memory with the free command and the -h human-readable flag

# free -ht
              total        used        free      shared  buff/cache   available
Mem:           755G        321G        3.0G         62G        430G        670G
Swap:            4G          1G          3G
Total:         771G        322G          6G

Display the swap usage summary by device using swapon. Same as cat /proc/swaps

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