How to configure Swap Space in Linux April 17, 2025

This article explains how to configure Swap Space in Linux. It is important for managing memory efficiently during heavy workloads. Swap space acts as a backup for physical RAM and can be set up as a swap file or a dedicated partition.

Follow the below steps to configure swap space:

1. Check existing Swap Space before adding it:
   1.  Show swap details:

      $ sudo swapon --show

   2. View overall memory usage:

      $ free -h

      If no output is returned, swap space is not configured.

2. Creating a Swap File
   To add swap space without changing partitions, follow these steps:
   1. Create the Swap File:

      $ sudo dd if=/dev/zero of=/swapfile bs=1M count=1024

      Replace 1024 with the desired size in MB (e.g., 2048 for 2GB).

   2. Set File Permissions:

      $ sudo chmod 600 /swapfile

   3. Format the File as Swap:

      $ sudo mkswap /swapfile

   4. Activate the Swap File:

      $ sudo swapon /swapfile

   5. Make it Permanent: Add this line to /etc/fstab:

      /swapfile none swap sw 0 0

3.  Configuring a Swap Partition
   For long-term performance, a dedicated swap partition is often chosen:
   1. Identify or Create a Partition:
      List available partitions using:

      $ sudo fdisk -l

      Create a new partition using fdisk or a similar tool, and set its type to Linux swap (type 82).

   2. Format the Partition:

      $ sudo mkswap /dev/sdX

      Replace /dev/sdX with your partition’s identifier (e.g., /dev/sda3).

   3. Activate the Swap Partition:

      $ sudo swapon /dev/sdX

   4. Make it Persistent: Add this line to /etc/fstab:

      /dev/sdX none swap sw 0 0

4. Adjusting Swap Settings
   1.  Check current “swappiness” value (controls swap usage frequency):

      $ cat /proc/sys/vm/swappiness

   2. Temporarily adjust swappiness:

      $ sudo sysctl vm.swappiness=10

   3. For permanent changes, add this to /etc/sysctl.conf:

      swappiness=10

This way, you can configure swap space as it ensures stable performance, especially for memory-intensive tasks or servers. If you need assistance, feel free to contact our support staff.

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