How to Add Swap Space on AlmaLinux 10

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Swap space is used when the system's physical memory (RAM) is full, providing additional virtual memory by utilizing disk space. Follow this guide to add a swap file as swap space on an AlmaLinux 10 system.

Check Current Swap Space

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To check the existing swap space on your system, run the following command:

swapon --show

Output:

NAME      TYPE      SIZE   USED   PRIO

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

To verify memory and swap details:

free -h

Output:

[root@server ~]# free -h
               total        used        free      shared  buff/cache   available
Mem:           5.5Gi       434Mi       5.1Gi       8.5Mi       171Mi       5.1Gi
Swap:          2.0Gi          0B       2.0Gi

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Create a Swap File

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To create a swap file with a size of 2GB (adjust the size as needed), use the following command:

fallocate -l 2G /swapfile

If fallocate is not available, use:

dd if=/dev/zero of=/swapfile bs=1M count=2048

Set the correct permissions for the swap file:

chmod 600 /swapfile

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Set Up the Swap File

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Now, format the file as swap space:

mkswap /swapfile

Output:

[root@server ~]# mkswap /swapfile
Setting up swapspace version 1, size = 2 GiB (2147479552 bytes)
no label, UUID=1009a4b9-7853-40f6-bb06-eac347b6f6c8

Enable the swap file:

swapon /swapfile

To verify that the swap space is active, run:

swapon --show

Output:

[root@server ~]# swapon --show
NAME      TYPE      SIZE USED PRIO
/dev/vda3 partition   2G   0B   -2
/swapfile file        2G   0B   -3

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Make the Swap File Permanent

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Edit the /etc/fstab file to ensure the swap file is enabled at boot:

nano /etc/fstab

Add the following line to the file:

/swapfile none swap sw 0 0

Save and exit the editor (Ctrl+O, Enter, Ctrl+X).

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Adjust Swap Settings (Optional)

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Modify the swappiness value to control the frequency of swap usage:

sysctl vm.swappiness=10

To make this change permanent, add the following line to /etc/sysctl.conf:

vm.swappiness=10

Reload the settings:

sysctl -p

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Verify Swap Configuration

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Confirm that the swap file is active and permanent by running the following commands:

swapon --show
cat /proc/swaps
free -h

Output:

NAME      TYPE      SIZE USED PRIO
/dev/vda3 partition   2G   0B   -2
/swapfile file        2G   0B   -3

[root@server ~]# free -h
               total        used        free      shared  buff/cache   available
Mem:           5.5Gi       451Mi       3.1Gi       8.5Mi       2.2Gi       5.1Gi
Swap:          4.0Gi          0B       4.0Gi

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Conclusion

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You have successfully added and configured swap space on AlmaLinux 10. The swap file will now be used as virtual memory whenever physical memory runs low, ensuring smoother system performance.