Swap is a location on harddisk is used as Memory by the operating system. When the operating systems detects that main memory is getting full and required more RAM to run applications properly it check for swap space and transfer files there. In general terms, swap is a part of the hard disk used as RAM on the system.
I have a virtual machine running which don’t have swap on it. Many times services got crashed due to insufficient memory. In this situation creation of Swap file is better to keep them up. This article will help you to create a swap file on Linux system after installation.
How to Add Swap in Ubuntu 20.04
Follow the below steps to create and enable Swap memory on your Ubuntu system.
1. Check Current Swap
Before working make sure that system has already swap enabled. If there is no swap, you will get output header only.
sudo swapon -s
2. Create Swap File
Lets create a file to use for swap in system of required size. Before making file make sure you have enough free space on disk. Generally, it recommends that swap should be equal to double of installed physical memory.
My Digital ocean droplet has 2GB memory. So creating the swapfile of 4GB in size.
sudo fallocate -l 4G /swapfile chmod 600 /swapfile
The, make it to swap format and activate on your system by running following commands:
sudo mkswap /swapfile sudo swapon /swapfile
3. Make Swap Permanent
After running above commands, Swap memory is added to your system and operating system can use when required. But after reboot of system swap will deactivate again.
You can make it permanent by appending the following entry in /etc/fstab file. Edit fstab file in editor:
sudo vim /etc/fstab
and add below entry to end of file:
/swapfile none swap sw 0 0
Save file and close. Now Swap memory will remain activate after system reboots.
4. Check System Swap Memory
You have successfully added swap memory to your system. Execute one of the below commands to view current active swap memory on your system:
sudo swapon -s free -m
5. Update Swappiness Parameter
Now change the swappiness kernel parameter as per your requirement. It tells the system how often system utilize this swap area.
Edit /etc/sysctl.conf file:
sudo vim /etc/sysctl.conf
append following configuration to end of file
vm.swappiness=10
Now reload the sysctl configuration file
sudo sysctl -p
Conclusion
In this tutorial, you have learned about creating of Swap memory on Ubuntu system.