How to create swapfile

Swapfile comes really handy when you want to increase or change the size of your swap space.

Allocate:

Using Ubuntu you can allocate your required space using user-friendly command as follows:

fallocate -l 4G /swapfile

Or you might want to go through the hard way :

dd if=/dev/zero of=/swapfile bs=1024 count=65536

Explanation: Set the size to the count argument as megabytes multiply 1024, for example 64 MB would be 64x1024=65536 or 8 GB would be 8x1024x1024=8388608

Now apply correct permissions, so that only root can access it :

chmod 600 /swapfile

Create and Turn-on:

Using following command the previously allocated space will be converted to a swap space :

mkswap /swapfile

Now, test your newly created swapfile:

swapon /swapfile

Make it permanent:

You can make it permanent by adding to the /etc/fstab file:

/swapfile   none    swap    sw    0   0

Tune it:

Now, lower the swapiness and cache pressure by putting these values into your /etc/sysctl.conf file:

vm.swappiness=10
vm.vfs_cache_pressure = 50

Good Luck!

Reference: DigitalOcean