Why should I care if my server is using swap?

  • Swap is slower than RAM
  • Swap is written to SSD, which has a limited number of write cycles, while RAM is not
  • You spent money on RAM, don’t waste it

Swappiness value

  • Range: 0-100
  • Default: 60
  • 0: Swap is used only when absolutely necessary
  • 100: Swap is used as much as possible

Check swappiness value

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cat /proc/sys/vm/swappiness

Change swappiness value

Temporarily

1
sudo sysctl vm.swappiness=10

Permanently

  • Edit /etc/sysctl.conf
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sudo nano /etc/sysctl.conf
  • Add/modify the following line
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vm.swappiness=<value>
  • Reload the configuration
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sudo sysctl --load=/etc/sysctl.conf

References

High swap usage on Ubuntu server | https://serverfault.com/a/1108210