Turn off swap

Photo of author
Written By Jan Reilink

Windows Server system administrator & enthusiast.

Not every Linux server I maintain needs to have a swap partition and to start swapping. For instance, the MySQL servers all have more than enough RAM on board to do their work. Yet, when a swap partition is enabled Linux starts swapping, which may degrade MySQL database performance…

Bash script to turn off Linux swap

An unwanted Linux swap partition can be the result of an automated and unattended Linux installation. Of course you can fiddle with the Linux kernel swapiness settings, located in /proc/sys/vm/swapiness and configurable in /etc/sysctl.conf, but one can turn off the swap completely too.

Here’s a tiny bash script to disable Linux’ swap – for which we use the swapoff command – and to comment out the swap partition in /etc/fstab

#!/bin/bash # swapoff -a to disable swapping swapoff -a # sed to comment the swap partition in /etc/fstab sed -i.bak -r 's/(.+ swap .+)/#\1/' /etc/fstab
Code language: Bash (bash)

Save this as turn_swap_off.sh and execute as root:

sh /root/turn_swap_off.sh
Code language: Bash (bash)

A backup of the /etc/fstab file is made just to be sure and to stay on the safe side.

Did you like: Turn off swap

Then please, take a second to support Sysadmins of the North and donate!

Your generosity helps pay for the ongoing costs associated with running this website like coffee, hosting services, library mirrors, domain renewals, time for article research, and coffee, just to name a few.

2 thoughts on “Turn off swap”

  1. Hi Jan,

    Instead of using a complete partition as swap. You can also use a swapfile which is much more flexible. You can even use more than one swapfile on other devices. It makes your systems much more responsive. Without getting stuck on low free RAM.

    # dd if=/dev/zero of=/swapfile bs=1M count=512
    # chmod 600 /swapfile
    # mkswap /swapfile
    # swapon /swapfile

    Edit the /etc/fstab to auto-enable the swapfile:
    /swapfile none swap defaults 0

    and for removing it:

    # swapoff -a
    # rm -f /swapfile
    • Hi Brian, thank you for your comment :)

      Great point! However, in my opinion – and with current amounts of RAM available in systems – the need for swap often indicates a problem elsewhere. And on mission critical systems like our MySQL servers, you don’t want degraded performance because of swapping data in and out.

      OTOH, if you have RAM to spare, here’s how to create a nifty RAM disk in Linux:
      https://www.saotn.org/linux-ramdisk-mini-howto/ :-)


Hi! Join the discussion, leave a reply!

%d bloggers like this: