Understanding and Configuring Swap Space on Ubuntu Linux

Swap space plays a crucial role in the performance and stability of a Linux system, especially when the physical RAM is fully utilized. In this article, we’ll explore the concept of swap space, its significance, and the steps to configure it on Ubuntu Linux.

What is Swap Space?

Swap space, also known as virtual memory, is a designated area on a storage device that the operating system uses as an extension of physical RAM. When the RAM is fully occupied, the system can transfer less frequently used data to the swap space to free up RAM for more critical processes. This prevents the system from becoming unresponsive due to memory exhaustion.

Why Do You Need Swap Space?

1. Preventing Out of Memory Issues: In situations where physical RAM is insufficient, having swap space prevents the system from running out of memory. This helps avoid crashes or freezes due to lack of available memory.
2. Handling Hibernation: Swap space is crucial for hibernation functionality. When a system hibernates, the contents of the RAM are written to the swap space, allowing the system to resume its state when powered on again.
3. Supporting Memory-Intensive Tasks: Swap space allows the system to handle memory-intensive tasks that may exceed the available physical RAM.

How To Add Swap Space on Ubuntu 22.04 LTS

Adding swap space on Ubuntu 22.04 LTS involves a few steps. Swap space is used as virtual memory when your system’s physical RAM is fully utilized. Here’s a step-by-step guide to add swap space:

Method 1: Create a Swap File

1. Check Current Swap:

Before adding swap space, check if you already have a swap partition or file by running:

$ swapon --show

2. Create a Swap File:

If we don’t have an existing swap file, you can create one. The size of the swap file depends on your system’s requirements. For example, to create a 2GB swap file:

$ sudo fallocate -l 2G /swapfile

If fallocate is not available, you can use dd:

$ sudo dd if=/dev/zero of=/swapfile bs=1M count=2048

3. Set Permissions:

Ensure that only the root user can read and write to the swap file:

$ sudo chmod 600 /swapfile

4. Make it a Swap Space:

Mark the file as swap:

$ sudo mkswap /swapfile

5. Activate the Swap File:

Enable the swap file:

$ sudo swapon /swapfile

To make the swap file permanent, add it to the /etc/fstab file:

$ echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab

Method 2: Create a Swap Partition

1. Create a Partition:

Use a partitioning tool (e.g., fdisk or gparted) to create a new partition. Mark the partition type as 82 (Linux swap).

2. Format the Partition:

Format the partition as swap:

$ sudo mkswap /dev/sdXn

Replace /dev/sdXn with our actual partition identifier.

3. Activate the Swap Partition:

Enable the swap partition:

$ sudo swapon /dev/sdXn

To make the swap partition permanent, add it to the /etc/fstab file:

$ echo '/dev/sdXn none swap sw 0 0' | sudo tee -a /etc/fstab

Verify

Verify that the swap space is added by running:

$ free -h

We should see the swap space in the output. Remember to adjust the size of the swap space according to your system requirements. If your system has an SSD, consider using a smaller swap space, or none at all, as SSDs have limited write endurance.