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Swap file on a low-RAM VPS

Add swap space on a small VPS (512MB-2GB RAM) to prevent the OOM killer from taking down services during a memory spike, especially during package installs/builds.

Target: Ubuntu / Debian / any Linux with a standard filesystemServer AdministrationOfficial homepage ↗Official docs ↗
This guide is synthesized from Swap file on a low-RAM VPS's own official documentation, linked above — always cross-check exact package/version names there before running these commands on a production server, since distro and project versions move over time.

  1. 1Check if swap already exists

    sudo swapon --show
    free -h

  2. 2Create a swap file

    sudo fallocate -l 2G /swapfile
    sudo chmod 600 /swapfile
    sudo mkswap /swapfile
    sudo swapon /swapfile

    2G is a reasonable default for a 512MB-1GB RAM VPS -- adjust to roughly 1-2x your RAM size. If fallocate isn't supported on your filesystem, use: sudo dd if=/dev/zero of=/swapfile bs=1M count=2048

  3. 3Make it permanent across reboots

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

  4. 4Tune swappiness for a server workload

    The default swappiness (60) favors swapping proactively, which fits desktop use better than a server -- a lower value keeps data in RAM longer.

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