SWAPMemoryPerformance4 min read

Configure SWAP memory

Create and configure SWAP memory to prevent processes from being killed due to low RAM on your VPS.

SWAP provides overflow space when physical RAM is full. It prevents out-of-memory crashes on VPS instances with limited RAM.

Step 1 — Check current swap

bash
sudo swapon --show
free -h

If no output from swapon, no swap is configured.

Step 2 — Create a swap file

Recommended sizes:

1 GB RAM → 2 GB swap
2 GB RAM → 2 GB swap
4 GB RAM → 4 GB swap
8+ GB RAM → 4 GB swap

bash
sudo fallocate -l 2G /swapfile

If fallocate is not available:

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

Step 3 — Set permissions and format

bash
sudo chmod 600 /swapfile
sudo mkswap /swapfile

Step 4 — Enable the swap

bash
sudo swapon /swapfile

Verify:

bash
free -h

Step 5 — Make it permanent

Add to /etc/fstab so it persists after reboot:

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

Step 6 — Adjust swappiness

Swappiness controls how aggressively the kernel uses swap (0-100). For a VPS, 10 is recommended:

bash
sudo sysctl vm.swappiness=10

Make it permanent:

bash
echo 'vm.swappiness=10' | sudo tee -a /etc/sysctl.conf

Step 7 — Adjust cache pressure

bash
sudo sysctl vm.vfs_cache_pressure=50
echo 'vm.vfs_cache_pressure=50' | sudo tee -a /etc/sysctl.conf

Remove swap (if needed)

bash
sudo swapoff /swapfile
sudo rm /swapfile

Remove the line from /etc/fstab.

Note

Swap on SSD/NVMe (like Baires Host VPS) is fast but still slower than RAM. Use swap as a safety net, not as a substitute for adequate RAM. If your VPS consistently uses swap, consider upgrading your plan.

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