How to Add SWAP Space in Ubuntu 20.04 – Google Cloud

How to Add SWAP Space in Ubuntu 20.04 on Google Cloud. Swap space is a virtual memory extension of the system or servers real memory (RAM). If you have swap space configured your server will behave as it has additional memory than it actually have.

This guide helps you to configure swap space on Ubuntu 20.04.

This setup is tested on Google Cloud Compute Engine instance running Ubuntu 20.04 with 614 MB RAM. So, this setup will work on any cloud servers or any VPS or any dedicated servers.

Prerequisites

1. A running Compute Engine, see the Setting up Compute Engine Instance with Ubuntu 20.04.

Before Begin

You need to know how much RAM memory you have in your machine.

The general rule to allocate how much swap space is necessary is as follows.

• Systems with less than 2 GB RAM – twice the amount of RAM.
• Systems with 2 to 8 GB RAM – the same size as the amount of RAM.
• Systems with more than 8 GB RAM – at least 4 GB of Swap.

Check Swap Space

Check whether your Ubuntu server already has a swap space available. More often virtual machines don’t have a swap space enabled by default. Check swap space using the following command.

sudo swapon --show

If you don’t get any output, then your server don’t have any swap space configured. So you can proceed to add swap memory.

01. Create a Swap File

In the current situation with 614 MB RAM we are going to create a swap space of 1GB.

Create a swap file to add 1 GB (1G) space. You can also increase the amount of space you need.

sudo fallocate -l 1G /swapfile

02. Adjust Swap File Permissions

Now you have a swap file of correct size and can be enabled as swap space.

Proceed by setting up correct permissions.

sudo chmod 600 /swapfile

03. Configure Swap Space

You can now mark the file as swap space with the mkswap command.

sudo mkswap /swapfile

You will receive the output similar to this.

Output
Setting up swapspace version 1, size = 1024 MiB (1073737728 bytes)
no label, UUID=f59595fb-754b-47ae-af6b-8dd6e98654d8

04. Enable Swap Space

Enable the swap space and allow the system to utilise the space.

sudo swapon /swapfile

Verify that the swap is available by typing:

sudo swapon --show

Output
NAME      TYPE  SIZE USED PRIO
/swapfile file 1024M   0B   -2

You can check the output of the free utility again.

free -h

Output
               total        used       free        shared      buff/cache  available
Mem:           581M         275M        62M        103M        243M        110M
Swap:          1.0G          0B        1.0G

05. Make Swap as Permanent

Now swap space is only created for the current session. If you reboot the server the current changes will be gone. So you can make this setting permanent by adding the swap file to our /etc/fstab file.

sudo nano /etc/fstab

Add the following at the end of the file.

/swapfile swap swap defaults 0 0

Configure Swappiness Value

The swappiness parameter allow to configure how often your system swaps data out of RAM to the swap space.

This value will be between 0 to 100 in percentage. The values close to zero, the kernel will not swap data to the disk unless absolutely necessary. The higher the value that are closer to 100 will try to put more data into swap in an effort to keep more RAM space free.

So, telling the system not to rely on the swap much will generally make your system faster.

You can see the current swappiness value by typing:

cat /proc/sys/vm/swappiness

Output
60

Now set the value to 10 with the following command.

sudo sysctl vm.swappiness=10

Output
vm.swappiness = 10

You can make this value permanent by adding the line to your /etc/sysctl.conf file.

sudo nano /etc/sysctl.conf

At the bottom, add the following line.

vm.swappiness=10

Hit Ctrl+X followed by Y and Enter to save and close the file.

Removing Swap Space

To remove a swap space you need to swapoff the space, remove the entry from the /etc/fstab file and finally delete the swap file.

sudo swapoff -v /swapfile

Edit the /etc/fstab file and remove the swap file entry /swapfile swap swap defaults 0 0

Finally, delete the swap file.

sudo rm /swapfile

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Conclusion

Now you have learned how to create swap space and configure it and remove the swap space on your Ubuntu 20.04 server on Google Cloud.

Thanks for your time. If you face any problem or any feedback, please leave a comment below.