In this guide, we want to show you to Add Swap Space (Swap File) on AlmaLinux 9.
Swap space in Linux is used when the amount of physical memory (RAM) is full. If the system needs more memory resources and the RAM is full, inactive pages in memory are moved to the swap space. While swap space can help machines with a small amount of RAM, it should not be considered a replacement for more RAM. Swap space is located on hard drives, which have a slower access time than physical memory.
Swap space can be a dedicated swap partition (recommended), a swap file, or a combination of swap partitions and swap files.
In this guide, we will show how to create and enable a swap file on AlmaLinux 9.
Steps To Add Swap Space on AlmaLinux 9
To complete this guide, you must log in to your server as a non-root user with sudo privileges. To do this, you can follow our guide on Initial Server Setup with AlmaLinux 9.
Check Server Storage for Swap
First, you need to check your server’s storage to see if you already have some swap space available.
You can see if the system has any configured swap by using
swapon command, a general-purpose swap utility.
Note: If nothing is returned by the command, then the summary was empty and no swap file exists.
Another way is with the
free utility, which shows us the system’s overall memory usage. You can see our current memory and swap usage (in megabytes) by typing:
Output total used free shared buffers cached Mem: 3953 315 3637 8 11 107 -/+ buffers/cache: 196 3756 Swap: 0 0 4095
As you can see, our total swap space in the system is 0. This matches what we saw with
At this point, you should check your available storage space on your AlmaLinux 9 server. To do this, you can use the following command:
Output Filesystem Size Used Avail Use% Mounted on /dev/vda1 59G 1.5G 55G 3% / devtmpfs 2.0G 0 2.0G 0% /dev tmpfs 2.0G 0 2.0G 0% /dev/shm tmpfs 2.0G 8.3M 2.0G 1% /run tmpfs 2.0G 0 2.0G 0% /sys/fs/cgroup
As you can see on the first line, our storage partition has 59 gigabytes available, so we have quite a bit of space to work with.
Note: Keep in mind that this is on a fresh, medium-sized VPS instance, so your actual usage might be very different.
Since my system has 4 gigabytes of memory and doubling that would take a larger chunk from my storage space than I am willing to part with, I will create a swap space of 4 gigabytes to match my system’s memory.
Create a Swap File on AlmaLinux 9
At this point, we will create a file named swapfile in our root “/” directory. To do this, you can use the
sudo dd if=/dev/zero of=/swapfile count=4096 bs=1MiB
This command will create a 4GiG file.
Then, you can verify that the correct amount of space was reserved for swap by using
ls -lh /swapfile
Output -rw-r--r-- 1 root root 4.0G Feb 11 11:00 /swapfile
Now you have a swap file and you must enable it.
Enable Swap File on AlmaLinux 9
At this point, you need to tell your system to format this file as a swap and then enable it.
First, you should set the correct permissions for the swap file to increase your security:
sudo chmod 600 /swapfile
This will restrict both read and write permissions to the root account only.
Verify that the swap file has the correct permissions by using
ls -lh again:
ls -lh /swapfile
-rw------- 1 root root 4.0G Feb 11 11:00 /swapfile
Then, you can tell your system to set up the swap space for use by running the following command:
sudo mkswap /swapfile
Output Setting up swapspace version 1, size = 4194300 KiB no label, UUID=b99230bb-21af-47bc-8c37-de41129c39bf
At this point, your swap file is ready to use as a swap space. To begin using it, run the command below:
sudo swapon /swapfile
You can see if the system has any configured swap again:
Output Filename Type Size Used Priority /swapfile file 4194300 0 -1
Also, you can use the
free utility again to corroborate your findings:
Output total used free shared buffers cached Mem: 3953 315 3637 8 11 107 -/+ buffers/cache: 196 3756 Swap: 4095 0 4095
At this point, your swap file is enabled at the moment, but when you reboot, the server will not automatically enable the file for use. You can change that by modifying the
fstab file, which is a table that manages filesystems and partitions.
Edit the file with
sudo privileges in your text editor:
sudo vi /etc/fstab
At the bottom of the file, you need to add a line that will tell the operating system to automatically use the swap file that you created:
/swapfile swap swap sw 0 0
When you are finished adding the line, you can save and close the file. The server will check this file on each bootup, so the swap file will be ready for use from now on.
At this point, you have learned to Add Swap Space (Swap File) on AlmaLinux 9.
Hope you enjoy it. You may be like these guides on the Orcacore website:
Install and Configure Squid Proxy on AlmaLinux 9
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