Gremoire

How to Add and Remove Swap Space on a Linux Server ​

Swap space acts as an overflow for your system's RAM, storing inactive memory pages on disk to avoid crashes or slowdowns when RAM usage is high. In this guide, you’ll learn how to safely create swap space, configure it for performance, and remove it when no longer needed.

Why Add Swap Space? ​

Even if you have decent RAM, swap space helps:

  • Prevent system freezes or crashes when memory is full.
  • Keep inactive background apps out of RAM.
  • Enable hibernation (for desktop systems).
  • Support memory-hungry processes like databases, compilers, or containers.

How to Add Swap Space (Swap File Method) ​

Step 1: Create a Swap File ​

bash
sudo fallocate -l 2G /swapfile

Replace 2G with your desired size (e.g., 1G, 4G, etc.)

Step 2: Secure the File ​

bash
sudo chmod 600 /swapfile

Step 3: Format as Swap ​

bash
sudo mkswap /swapfile

Step 4: Enable Swap ​

bash
sudo swapon /swapfile

Step 5: Make It Permanent ​

Add it to your /etc/fstab so it's available on reboot:

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

Optional: Tune Swappiness (Use RAM Before Swap) ​

bash
# Check current swappiness (default is 60)
cat /proc/sys/vm/swappiness

# Set it to 10 (less swap usage)
sudo sysctl vm.swappiness=10

# Make it permanent
echo 'vm.swappiness=10' | sudo tee -a /etc/sysctl.conf

How to Remove Swap Space ​

If you no longer need the swap file, follow these steps to cleanly remove it.

Step 1: Turn Off Swap ​

bash
sudo swapoff /swapfile

Step 2: Delete the File ​

bash
sudo rm /swapfile

Step 3: Remove from fstab ​

Edit /etc/fstab to remove or comment out the swap line:

bash
sudo nano /etc/fstab

Delete this line if it exists:

/swapfile none swap sw 0 0

Step 4: (Optional) Restore Default Swappiness ​

If you previously set `vm.swappiness=10`, reset to default (usually 60):

bash
sudo sysctl vm.swappiness=60

Or remove the entry from `/etc/sysctl.conf`.

Verify Your Changes ​

bash
free -h
  • After adding swap, you should see it listed.
  • After removal, swap should show `0B`.

What's Next? ​

1. Make Swap Permanent (so it survives reboot) ​

Run this if you haven't already:

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

2. (Optional) Tune Swappiness ​

To make your system prefer RAM and use swap only when needed, reduce the swappiness value:

bash
# Temporarily set swappiness to 10 (default is 60)

sudo sysctl vm.swappiness=10

# Make it permanent across rebootsecho 'vm.
swappiness=10' | sudo tee -a /etc/sysctl.conf

Final Thoughts ​

Adding swap space is a quick and effective way to boost stability, especially on low-memory servers. It's not a replacement for RAM, but it's a critical tool to avoid downtime, especially in production environments.