Setting Swapfile on Ubuntu
When you are running out of memory on your Linux system, the OS starts killing processes to free up the memory. This is not a good idea, as it can lead to data loss. To avoid this, a swap file is used. By default, Ubuntu creates a swap file during installation. However, if you want to create a new swap file or change the size of the existing swap file, you can do so by following the steps below.
How to check if a swap file is already present?
To check if a swap file is already present, run the following command:
sudo swapon --show
You should see the swap file listed if it is present. On my system, the output is as follows:
NAME TYPE SIZE USED PRIO
/dev/dm-2 partition 1.9G 0B -2
Ubuntu has stopped using swap partitions and has started using swap files. But for me, the swap file is not listed instead a swap partition is listed - /dev/dm-2.
How to set it up then?
open a terminal and follow the steps below:
List the current swap file
sudo swapon --show
# NAME TYPE SIZE USED PRIO
# /dev/dm-1 file 20G 0B -2
Switch off the running swap file (this will take a while depending on the file size)
sudo swapoff /dev/dm-1
Create a new file with required file size, here is an example of one with 16 GB
sudo fallocate -l 16G /swapfile
Change the access permissions so that only root can access it
sudo chmod 0600 /swapfile
Set this as the swap space
sudo mkswap /swapfile
Activate the swap space
sudo swapon /swapfile
You can confirm if by typing
sudo swapon --show
# NAME TYPE SIZE USED PRIO
# /swapfile file 20G 0B -2
Make it persistent, so that the swap file is mounted automatically on system boot. There are two ways to do this:
# Create a backup of the fstab
sudo cp /etc/fstab /etc/fstab.bak
# Edit the fstab file
sudo nano /etc/fstab
# Add the following line at the end of the file
/swapfile swap swap defaults 0 0
OR
Instead of using nano, you can use the following command to append the line to the end of the file:
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab
Conclusion
That’s it! You have successfully set up a swap file on your Ubuntu system. If you have any questions or face any issues, feel free to leave a comment below.