RAM is composed of chunks of memory called Pages. When programs execute, it takes fills up pages. Due to this sooner or later memory will run out. In order to free up the RAM, Pages can be swapped into hard drive and the freed up RAM can be used by the other program which needs CPU’s attention.
Swap space is not a must in Linux. So if you happen to have a system that does not have Swap space, then follow the below guide to create a swap file and use it.
Check whether a SWAP space is enabled
sudo swapon -s
if you do not have swap enabled in the system you should see the output as below
Filename Type Size Used Priority
Check the system for available space.
The recommended swap file size is twice the size of the RAM size. If your RAM
size is 512 MB, then the SWAP file size should be 1GB.
size is 512 MB, then the SWAP file size should be 1GB.
dfFilesystem 1K-blocks Used Available Use% Mounted on
/dev/vda 20642428 2367536 17226316 13% /
tmpfs 254432 0 254432 0% /lib/init/rw
udev 249612 60 249552 1% /dev
tmpfs 254432 4 254428 1% /dev/shm
Allocate space for swapfile
sudo fallocate -l 1GB /swapfile
Create Swap file
sudo mkswap /swapfile
the output will look like below
Setting up swapspace version 1, size = 8388608 KiB no label, UUID=103c4545-5fc5-47f3-a8b3-dfbdb64fd7eb
Turn on the SWAP file
sudo swapon /swapfile
You will then be able to see the new swap file when you view the swap summary.
swapon -s Filename Type Size Used Priority /swapfile file 8388608 0 -1
TO add this partition permanently, add it into /etc/fstab
sudo nano /etc/fstab/swapfile none swap sw 0 0
save and close the fstab file.