Enable Linux swap (by image file) - always I forget how to set Linux swap so there it is

Linux Swap.md

How to enable swap memory on Linux

Always I forget how to set Linux swap so there it is

Steps:

1. check swap
2. check disk size
3. create swap file (with 4GB)
4. fix permissions for root
5. create swap area
6. enable swap in linux using the new file
7. configuring swap partition to start when restarted vm
8. check if swap enabled (again)
9. check swappiness
10. set swappiness in running machine
11. configure swappiness to be set when restarted vm

1. check swap

sudo free -m
sudo swapon --show

2. check disk size

df -h

3. create swap file (with 4GB)

sudo fallocate -l 4G /swap.img

or you can call dd if you don't have fallocate command

dd command alternative: $ sudo dd if=/dev/zero of=/swap.img bs=1024 count=4194304

4. fix permissions for root

sudo chown root:root /swap.img
sudo chmod 600 /swap.img

5. create swap area

sudo mkswap /swap.img

6. enable swap in linux using the new file

sudo swapon /swap.img

7. configuring swap partition to start when restarted vm

sudo vim /etc/fstab

-> add file content:

/swap.img swap swap defaults 0 0

8. check if swap enabled (again)

sudo free -m
sudo swapon --show

9. check swappiness

cat /proc/sys/vm/swappiness

10. set swappiness in running machine

sudo sysctl vm.swappiness=10

11. configure swappiness to be set when restarted vm

sudo vim /etc/sysctl.conf

-> add file content:

vm.swappiness=10

Reference: https://linuxize.com/post/how-to-add-swap-space-on-ubuntu-22-04/