Add Swap partition on Ubuntu

In this tutorial we will add 1GB of Swap space to our Ubuntu 18.04 LTS.

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  1. Check if swap partition already exists:
    sudo swapon --show

    If the output is empty, you have no swap space enabled. Therefore, we need to create it.

  2. Create a Swap File
    sudo fallocate -l 1G /swapfile

    NOTE to self: in some very rare occasions this might fail, because “fallocate” is not installed: then try with this:
    sudo dd if=/dev/zero of=/swapfile bs=1024 count=1048576
  3. Set the correct permissions:
    sudo chmod 600 /swapfile
  4. Use the mkswap utility to set up a Linux swap area on the file:
    sudo mkswap /swapfile
  5. Activate the swap file:
    sudo swapon /swapfile
  6. Make sure the swap file is ON every time you reboot:
    sudo nano /etc/fstab
    …then add this anywhere within the file: /swapfile swap swap defaults 0 0
  7. Check again if the swap is working: sudo swapon --show
  8. Swappiness Value: this is ok to leave as is, but if you are low on RAM you should set it to a higher value. Default is 60. You can set it between 0 -100.
    Check current value: cat /proc/sys/vm/swappiness
    Set it to 10: sudo sysctl vm.swappiness=10

    If you want to make this effective even after reboot, then add it here:
    sudo nano /etc/sysctl.conf
    …then add this line within the file: vm.swappiness=10

If by any chance you need to remove the swap, then:
1. deactivate the space: sudo swapoff -v /swapfile
2. remove the swap file entry /swapfile swap swap defaults 0 0 from the /etc/fstab file.
3. remove the actual swapfile : sudo rm /swapfile

Good luck, have fun.

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