How To Add Swap Space on Debian 11

In this tutorial, we will show you how to add swap space on Debian 11. For those of you who didn’t know, Swap memory is a location on a hard disk to be used as Memory by the operating system. Simply put this means that if the system runs out of physical memory (RAM), then it will transfer some of the lesser-used data in RAM to this space.

This article assumes you have at least basic knowledge of Linux, know how to use the shell, and most importantly, you host your site on your own VPS. The installation is quite simple and assumes you are running in the root account, if not you may need to add ‘sudo‘ to the commands to get root privileges. I will show you the step-by-step add swap space on a Debian 11 (Bullseye).

Prerequisites

• A server running one of the following operating systems: Debian 11 (Bullseye).
• It’s recommended that you use a fresh OS install to prevent any potential issues.
• A non-root sudo user or access to the root user. We recommend acting as a non-root sudo user, however, as you can harm your system if you’re not careful when acting as the root.

Add Swap Space on Debian 11 Bullseye

Step 1. Before we install any software, it’s important to make sure your system is up to date by running the following apt commands in the terminal:

sudo apt update
sudo apt upgrade

Step 2. Add Swap Space on Debian 11.

First, check the swap space by running the following commands:

sudo swapon -s
free -m

If the output is empty, it means that the system doesn’t have swap space. If a partition is already existing, you should get at least one line as a result:

NAME      TYPE      SIZE USED PRIO
/dev/sda2 partition   8G   0B   -1

Now we create a file to use as a swap in your Debian system. Here we are creating a 2 GB swap file at /swapfile file. As shown below:

sudo fallocate -l 2G /swapfile 
chmod 600 /swapfile

Then, we have to tell the system that this file will be for the swap. This can be done with the command mkswap:

sudo mkswap /swapfile

Next, activate the swap memory on your Debian system:

sudo swapon /swapfile

To make the change permanent open the /etc/fstab file:

sudo nano /etc/fstab

Add the below entry to the end of the file:

/swapfile swap swap defaults 0 0

To verify that your swap space is active, you can run the initial command with the –show flag:

sudo swapon --show

Step 3. Configure Swappiness Value.

Swappiness is a Linux kernel property that defines how often the system will use the swap space. Swappiness can have a value between 0 and 100. The default value of swappiness is 60, which you can check by using the following command below:

cat /proc/sys/vm/swappiness

You can set the swappiness value by using “sysctl” command

sudo sysctl vm.swappiness=40

Step 4. Remove Swap Space File.

Removing swap partitions on Debian is pretty straightforward, follow the below steps:

• Deactivate the swap space by running:

sudo swapoff -v /swapfile

• Remove from /etc/fstab

Open the /etc/fstab file with your text editor and remove the swap file entry /swapfile swap swap defaults 0 0.

• Finally, delete the actual swapfile file using the following command below:

sudo rm /swapfile

Congratulations! You have successfully added swap space. Thanks for using this tutorial to add swap space on Debian 11 Bullseye. For additional help or useful information, we recommend you check the official Debian website.