Written by , Updated on May 29, 2020

Swap is a location on harddisk is used as Memory by the operating system. When the operating systems detects that main memory is getting full and required more RAM to run applications properly it check for swap space and transfer files there. In general terms, swap is a part of the hard disk used as RAM on the system.

I have a virtual machine running which don’t have swap on it. Many times services got crashed due to insufficient memory. In this situation creation of Swap file is better to keep them up. This article will help you to create a swap file on Linux system after installation.

Create Swap in Ubuntu 20.04

Follow the below steps to create and enable Swap memory on your Ubuntu system.

1. Check Current Swap

Before working make sure that system has already swap enabled. If there is no swap, you will get output header only.

sudo swapon -s

How to Create Swap in Ubuntu 20.04 Memory swap swapfile ubuntu ubuntu 20.04

2. Create Swap File on Ubuntu

Lets create a file to use for swap in system of required size. Before making file make sure you have enough free space on disk. Generally, it recommends that swap should be equal to double of installed physical memory.

My Digitalocean droplet has 2GB memory. So creating the swapfile of 4GB in size.

sudo fallocate -l 4G /swapfile
chmod 600 /swapfile

The, make it to swap format and activate on your system by running following commands:

sudo mkswap /swapfile
sudo swapon /swapfile

3. Make Swap Permanent

After running above commands, Swap memory is added to your system and operating system can use when required. But after reboot of system swap will deactivate again.

You can make it permanent by appending the following entry in /etc/fstab file. Edit fstab file in editor:

vim /etc/fstab

and add below entry to end of file:

/swapfile   none    swap    sw    0   0

How to Create Swap in Ubuntu 20.04 Memory swap swapfile ubuntu ubuntu 20.04

Save file and close. Now Swap memory will remain activate after system reboots.

4. Check System Swap Memory

You have successfully added swap memory to your system. Execute one of the below commands to view current active swap memory on your system:

sudo swapon -s
free -m

How to Create Swap in Ubuntu 20.04 Memory swap swapfile ubuntu ubuntu 20.04

5. Update Swappiness Parameter

Now change the swappiness kernel parameter as per your requirement. It tells the system how often system utilize this swap area.

Edit /etc/sysctl.conf file:

sudo vim /etc/sysctl.conf

append following configuration to end of file

vm.swappiness=10

Now reload the sysctl configuration file

sudo sysctl -p

Conclusion

In this tutorial, you have learned about creating of Swap memory on Ubuntu system.