Configuring swap space

Add swap space to prevent out-of-memory crashes during node operation.

Swap provides overflow memory on disk when physical RAM is exhausted. It prevents out-of-memory crashes but is significantly slower than real RAM.

Check existing swap

swapon -s

If this shows an active swapfile, swap is already configured — skip to the next section.

Example of enabled swap

Recommended swap size

Server RAM	Swap size
4 -- 16 GB	8 GB
16+ GB	16 GB

Swap is not a replacement for physical RAM. If your server constantly uses swap, upgrade memory instead.

Create and enable swap

1. Create an 8 GB swap file:

sudo fallocate -l 8G /swapfile

1. Restrict permissions:

sudo chmod 600 /swapfile

1. Initialize and enable the swap area:

sudo mkswap /swapfile
sudo swapon /swapfile

1. Make swap persistent across reboots:

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

1. Verify swap is active:

sudo swapon --show
free -h

1. Tune swap behavior:

echo 'vm.swappiness=10' | sudo tee -a /etc/sysctl.conf
echo 'vm.vfs_cache_pressure=50' | sudo tee -a /etc/sysctl.conf
sudo sysctl -p