If your VPS is running out of memory, adding or increasing swap space can instantly improve stability. Swap helps your Ubuntu server handle occasional spikes in RAM usage by providing extra virtual memory on disk. In this guide, you’ll learn how to create, enable, and verify swap space on Ubuntu 24.04 and 22.04, even on the smallest VPS plans.
Small VPS servers often come with limited RAM, and when memory runs out, your server may freeze, crash, or kill important processes like PHP-FPM or MySQL. Adding swap space is one of the simplest ways to stabilize your system without upgrading your VPS plan.
This guide shows you how to create, increase, enable, and optimize swap space on Ubuntu 24.04, 22.04, or any other modern Ubuntu release.
What Is Swap Space?
Swap is a reserved area on your disk that acts as virtual memory when RAM is full.
Swap helps:
Prevent out-of-memory (OOM) crashes
Stabilize PHP-FPM
Avoid MySQL shutdowns
Handle traffic spikes
Complete heavy tasks (Composer, Docker builds, imports)
Keep WordPress stable under load
Swap should NOT:
Replace RAM
Be used for constant heavy workloads
For most VPS servers, 1–2 GB of swap is enough.
Step 1: Check if Swap Already Exists
Run:
swapon --show
If there is no output, your server has no swap.
Check system memory:
free -h
You’ll see something like:
Swap: 0B 0B 0B
If swap exists, you’ll see numbers like:
Swap: 1.0G 50M 950M
Step 2: Create Swap File (Recommended Method)
Most VPS users should create swap using a swapfile — not partition.
Create a 2GB swap file:
fallocate -l 2G /swapfile
If fallocate doesn’t work (rare), use:
dd if=/dev/zero of=/swapfile bs=1M count=2048
Secure the swap file:
chmod 600 /swapfile
Turn swapfile into usable swap:
mkswap /swapfile
Enable swap:
swapon /swapfile
Verify:
swapon --show
free -h
You now have swap memory active.
Step 3: Make Swap Permanent
Add to /etc/fstab:
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab
This ensures swap loads on reboot.
Step 4: Choose the Right Swap Size
A basic rule:
| RAM | Recommended Swap |
|---|---|
| 1 GB | 1–2 GB |
| 2 GB | 1 GB |
| 4 GB | 1 GB or none |
| 8 GB+ | Swap optional |
For VPS servers running:
WordPress
Virtualmin
MariaDB
Composer/Docker tasks
2 GB is the sweet spot.
Step 5: Increase Swap Size (If You Already Have Swap)
If swap is too small, remove the old file and recreate a bigger one.
Disable current swap:
swapoff -a
Create larger file (example: 4GB):
fallocate -l 4G /swapfile
Secure & re-enable:
chmod 600 /swapfile
mkswap /swapfile
swapon /swapfile
Update fstab (if needed):
nano /etc/fstab
Ensure line exists:
/swapfile none swap sw 0 0
Step 6: Optimize Swap (Optional but Recommended)
1. Adjust swappiness
Controls how often Ubuntu uses swap.
Check current value:
cat /proc/sys/vm/swappiness
Default is often 60 (too aggressive).
Set to 10:
echo 'vm.swappiness=10' | sudo tee /etc/sysctl.d/99-swappiness.conf
sudo sysctl -p
2. Adjust cache pressure
Improves filesystem caching:
echo 'vm.vfs_cache_pressure=50' | sudo tee /etc/sysctl.d/99-cache-pressure.conf
sudo sysctl -p
Step 7: Verify Everything Works
Run:
free -h
swapon --show
You should see swap activated.
Reboot test:
reboot
After reboot:
swapon --show
If it shows your swapfile → your setup is successful.
When Should You NOT Use Swap?
Avoid swap if:
Your VPS uses slow HDD storage
Your workload is high-performance (DB-heavy)
You rely on predictable latency
For typical WordPress + Nginx + PHP-FPM + Virtualmin servers, swap is safe and recommended.
🎯 Conclusion
Adding swap space is one of the easiest and most effective ways to stabilize a VPS with limited RAM. It prevents service crashes, reduces downtime, and ensures smoother performance under load.
This guide works for:
Ubuntu 24.04
Ubuntu 22.04
Any VPS provider (Vultr, Hetzner, DO, Contabo, Linode, AWS Lightsail)
If you want deeper optimization, check out the next articles about slow plugins and MySQL bottlenecks.
