VPS Swap Configuration

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On November 8, 2025

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Add persistent swap space to prevent OOM errors on memory-constrained VPS.

Quick Setup

# Create 4GB swap file
sudo fallocate -l 4G /swapfile
sudo chmod 600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile

# Make persistent across reboots
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab

Verify

swapon --show
free -h

Expected output:

NAME      TYPE SIZE USED PRIO
/swapfile file   4G   0B   -2

Size Guidelines

RAM	Swap Size
2GB	2-4GB
4GB	2-4GB
8GB+	2GB

Adjust -l parameter: 1G, 2G, 4G, 8G

Tuning (Optional)

Swappiness (0-100, default 60): Lower = less aggressive swapping

# Check current
cat /proc/sys/vm/swappiness

# Set to 10 (conservative)
sudo sysctl vm.swappiness=10

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

Recommended values:

Desktop: 60 (default)
Server: 10-30
Database server: 1-10

Remove Swap

sudo swapoff /swapfile
sudo rm /swapfile
# Remove line from /etc/fstab
sudo sed -i '/swapfile/d' /etc/fstab

Troubleshooting

Swap not activating after reboot

# Check fstab entry
cat /etc/fstab | grep swap

# Manually activate
sudo swapon /swapfile

fallocate not supported (some filesystems)

# Use dd instead
sudo dd if=/dev/zero of=/swapfile bs=1M count=4096 status=progress
sudo chmod 600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile

Check swap usage