How to Permanently Disable Swap on Modern Linux Systems

Disabling Swap on Linux

<code>sed -ri 's/.*swap.*/#&/' /etc/fstab</code>

Previously you could disable swap by commenting the swap line in

/etc/fstab

and rebooting. From Ubuntu 20.04, CentOS Stream 10, openEuler 24.04, OpenCloudOS 9, Anolis OS 23, openSUSE 15 onward, that method no longer works.

Method 1

Systemd.swap units control swap after Ubuntu 20.04. Example commands:

<code># Show current swap
root@ubuntu2404:~# swapon --show
NAME      TYPE      SIZE USED PRIO
/dev/sda5 partition   4G   0B   -2

root@ubuntu2404:~# free -h
               total   used   free   shared  buff/cache   available
Mem:           1.9Gi  388Mi  1.4Gi   1.2Mi   286Mi   1.5Gi
Swap:          4.0Gi   0B   4.0Gi

# /etc/fstab entry
/dev/disk/by-uuid/e47400f5-4648-4aef-81de-dee66f909261 none swap sw 0 0

# List swap units
root@ubuntu2404:~# systemctl list-unit-files | grep swap
device-disk-by\x2duuid-e47400f5\x2d4648\x2d4aef\x2d81de\x2ddee66f909261.swap generated       -
swap.target                                 static

# Check swap.target status
root@ubuntu2404:~# systemctl status swap.target
● swap.target - Swaps
   Loaded: loaded (/usr/lib/systemd/system/swap.target; static)
   Active: active since Mon 2025-02-10 10:22:05 UTC; ...

# Mask swap.target
root@ubuntu2404:~# systemctl mask swap.target
Created symlink /etc/systemd/system/swap.target → /dev/null.

# Reboot and verify
root@ubuntu2404:~# swapon --show
# (no output)
root@ubuntu2404:~# free
... Swap: 0 0 0</code>

This method does not work on CentOS 7 and Ubuntu 18.04.

Method 2

Adding the

noauto

option to the swap entry in

/etc/fstab

prevents both systemd.swap and fstab from activating swap automatically.

<code># Example on Ubuntu/Debian
root@ubuntu2404:~# vi /etc/fstab
/dev/disk/by-uuid/e47400f5-4648-4aef-81de-dee66f909261 none swap sw,noauto 0 0

# Or using sed
sed -ri.bak '/swap/s/(.*)(sw)(.*)/\1\2,noauto\3/g' /etc/fstab

# Example on Rocky/AlmaLinux/CentOS/openEuler/openCloudOS/Anolis/openSUSE
root@openeuler24 ~]# vi /etc/fstab
UUID=2bd0a169-4f2b-4fce-8f4b-0b2ea6273990 none swap defaults,noauto 0 0

# Or using sed
sed -ri.bak '/swap/s/(.*)(defaults)(.*)/\1\2,noauto\3/g' /etc/fstab

# Reboot and verify
root@ubuntu2404:~# swapon --show
# (no output)
root@ubuntu2404:~# free
... Swap: 0 0 0</code>

Method 2 works on all tested systems.