How to Set up a Swap Space Using a File

This tutorial is suitable for any Linux distribution.

This procedure adds 6GB of swap to your server. If you want to add a different amount, replace 6G with the size you require.

Keep in mind that

swap size should be set to either total_mem/3 or 16GB - lower of the two.

total_mem is the total size of the nodes memory.

For example:

  • If the node total_mem is 18GB swap size should be set to 6GB.

  • If the node total_mem is 240GB swap size should be set to 16GB.

Procedure

  1. Create a file that will be used for swap.

    sudo fallocate -l 6G /swapfile
    
  2. Change the permissions setting on the file so that only the root user is be able to write and read the swap file.

    sudo chmod 600 /swapfile
    
  3. Run the Use mkswap utility to set up the file as Linux swap area.

    sudo mkswap /swapfile
    
  4. Enable the swap.

    sudo swapon /swapfile
    
  5. To make the change sustainable, open the /etc/fstab file and append the following:

    /swapfile swap swap defaults 0 0
    
  6. Verify that swap is active.

    sudo swapon --show
    NAME      TYPE  SIZE   USED PRIO
    /swapfile file 6024M 507.4M   -1
    

Remove a Swap File

  1. Deactivate Swap.

    sudo swapoff -v /swapfile
    
  2. Remove the sap file entry by editing the /etc/fstab file and removing /swapfile swap swap defaults 0 0.

  3. Delete the swap file.

    sudo rm /swapfile