How to increase swap space in Ubuntu

A very common problem is when we need to run memory memory-consuming applications and we lack free RAM and the swap is not big enough. In this case, we need to increase swap space, and it is possible to do it on the fly, without restarting the computer.

Usually, swap is 1000, or even more times slower than RAM, but this is not crucial, because it is a very common case, when a lot of memory is consumed by applications which do not require high performance at this point and they are okay to be kept is low swap space.

Check memory status

To check memory status, you can run command top, or use any graphical monitors

However, it is more professional to check the status of the system with special commands.

It is important to understand, shat swap is a system util and some of the operations required ROOT or SU priority. It is possible to see by the sudo command at the beginning of these commands subsequently entering the root password.

Check the status of the swap:

sudo swapon --show

the result will be something similar to:

[sudo] password for luxs: 
NAME       TYPE SIZE USED PRIO
/swapfile  file   2G   2G   -2
/swapfile1 file   4G 1.1G   -3

As you can see, I have two swap files

To check the total memory, use the command:

free -h

The results will be like this one:

               total        used        free      shared  buff/cache   available
Mem:           7.7Gi       4.7Gi       876Mi        98Mi       2.1Gi       2.6Gi
Swap:          6.0Gi       3.1Gi       2.9Gi

This is the overall status of the memory.

It is also important to understand, that you need to have enough space on the hard drive, and also, if you have a few hard drives, then you need to choose the fastest one.

Installing SWAP

Create the swap (/swapfile1) file with the size of 32GB.

sudo fallocate -l 32G /swapfile1

Change the mode of this file to be accessible for reading and writing only by root

sudo chmod 600 /swapfile1

Now, this file should be converted into a swap format by command:

sudo mkswap /swapfile1

That is, the file is ready and it can be activated by the command:

sudo swapon /swapfile1

Now you can check the status of the memory by describing the above commands, it is easy.

Permanent swap

This swap file will work only in this session, and after rebooting it will be disconnected. To make it connected, it is necessary to aff the following line: /swapfile1 none swap sw 0 0 to the file /etc/fstab. But before modifications, it is a good idea to make a backup copy of this file:

sudo cp /etc/fstab /etc/fstab.bak
echo '/swapfile1 none swap sw 0 0' | sudo tee -a /etc/fstab

This is how we do it in real-time:

Published: 2023-12-22 00:10:36
Updated: 2023-12-25 00:22:15