How to Add Swap Space on Ubuntu 23.10

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This guide is applicable only for KVM-based VPSes and dedicated servers, If you wish to increase swap on your OpenVZ-based VPS please contact us via a Support ticket from the client area.

Swap space, also known as "swap," is a reserved area on a server's storage device that the operating system can use as virtual memory when allocated memory is fully utilized. When your server's memory is exhausted due to running applications and processes, the operating system moves less frequently used data from memory to the swap space. This frees up memory for more active tasks and helps prevent the system from slowing down or crashing due to memory exhaustion.

Here's how to add swap space on an Ubuntu 23.10 server:

Check Swap Information

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Command to check swap size.

swapon --show

Output:

root@vps:~# swapon --show
NAME      TYPE SIZE USED PRIO
/swap.img file 3.8G   0B   -2
root@vps:~#

Or you can check using the free command.

free -m

Output:

root@vps:~# free -m
               total        used        free      shared  buff/cache   available
Mem:            3906         422        3273           0         440        3484
Swap:           3905           0        3905
root@vps:~#

NOTE: If the output is empty, it means that swap space is not enabled yet on your system.

Add Swap

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Command to create a Swap file.

NOTE: We are adding 1GB if you want to add a different size then you can replace it in place of 1G

fallocate -l 1G /swapfile

or

dd if=/dev/zero of=/swapfile bs=1024 count=1048576

To set write permission.[Default permissions only enable for root user]

chmod 600 /swapfile

To set up a swap area on the file.

mkswap /swapfile

Output:

root@vps:~# mkswap /swapfile
Setting up swapspace version 1, size = 1024 MiB (1073737728 bytes)
no label, UUID=2ac75219-0e57-41f0-abb9-4b09b887b9db
root@vps:~#

To activate the swap file.

swapon /swapfile

Open the following file and add the given content to change it to permanent.

nano /etc/fstab

Add the following line.

/swapfile swap swap defaults 0 0

Now check the swap size.

swapon --show

or

free -m

Output:

NAME      TYPE  SIZE USED PRIO
/swap.img file  3.8G   0B   -2
/swapfile file 1024M   0B   -3
root@vps:~#

Or

root@vps:~# root@vps:~# free -m
               total        used        free      shared  buff/cache   available
Mem:            3906         418        3275           0         442        3488
Swap:           4929           0        4929
root@vps:~#

NOTE: Now the added swap space can be seen.

Remove Swap

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Deactivate the swap space.

swapoff -v /swapfile

Output:

root@vps:~# swapoff -v /swapfile
swapoff /swapfile
root@vps:~#

Next, remove the following line from the file /etc/fstab

nano /etc/fstab

/swapfile swap swap defaults 0 0

Command to remove the file.

rm /swapfile

This concludes our topic of configuring swap in ubuntu.

If you can not configure and face technical difficulties, kindly reach out to us via Support Ticket.