Linux swap Guide

Linux Swap Guide

Complete beginner-friendly guide to swap on Linux, covering Arch Linux, CachyOS, and other distributions including swap files, swap partitions, swap configuration, and memory management.

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Table of Contents

1. Understanding Swap
2. Swap Partition
3. Swap File
4. Swap Configuration
5. Troubleshooting

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Understanding Swap

What is Swap?

Swap is virtual memory on disk.

Uses:

• Memory overflow: When RAM is full
• Hibernation: Save system state
• Memory management: Free up RAM
• System stability: Prevent OOM errors

When to use:

• Low RAM: Systems with limited memory
• Hibernation: Need to hibernate
• Memory-intensive: Running large applications

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Swap Partition

Create Swap Partition

Using fdisk:

# Create partition
sudo fdisk /dev/sda

# Create partition type 82 (Linux swap)
# Then format
sudo mkswap /dev/sda2

Format Swap

Format partition:

# Format as swap
sudo mkswap /dev/sda2

# With label
sudo mkswap -L "swap" /dev/sda2

Enable Swap

Activate swap:

# Enable swap
sudo swapon /dev/sda2

# Check status
swapon --show

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Swap File

Create Swap File

Create file:

# Create 2GB swap file
sudo fallocate -l 2G /swapfile

# Or use dd
sudo dd if=/dev/zero of=/swapfile bs=1M count=2048

Format Swap File

Format:

# Set permissions
sudo chmod 600 /swapfile

# Format as swap
sudo mkswap /swapfile

Enable Swap File

Activate:

# Enable swap file
sudo swapon /swapfile

# Check status
swapon --show

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Swap Configuration

fstab Entry

Auto-mount swap:

# Edit fstab
sudo vim /etc/fstab

Add:

# Swap partition
UUID=xxxx-xxxx  none  swap  defaults  0  0

# Or swap file
/swapfile  none  swap  defaults  0  0

Swap Priority

Set priority:

# In fstab
/swapfile  none  swap  defaults,pri=10  0  0

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Troubleshooting

Swap Not Working

Check status:

# Check swap
swapon --show

# Check usage
free -h

# Enable swap
sudo swapon -a

Swap Errors

Fix issues:

# Check swap file
sudo swapon --show

# Recreate if needed
sudo swapoff /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile

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Summary

This guide covered swap setup, swap files, and swap configuration for Arch Linux, CachyOS, and other distributions.

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Next Steps

• Filesystem Management - Filesystem setup
• fdisk Guide - Partitioning
• System Configuration - System setup
• swap Documentation: man swapon

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This guide covers Arch Linux, CachyOS, and other Linux distributions. For distribution-specific details, refer to your distribution's documentation.