Create Swap Partition on VPS Instances

If you are using a small VPS instance. Like an instance with half a Gig or one Gig of the RAM. You probably need to configure the swapfile on that instance in order to increase the performance.

So let’s see how to configure the swapfile on those instances.

Let’s say you have 512MB of RAM available and you want to make 1GB of swap.

The process goes like this.

• Create a file of size 1GB. fallocate is the tool for that.

  $ sudo fallocate -l 1G /swapfile

• Fill that file with zeros.

  $ sudo dd if=/dev/zero of=/swapfile  bs=1024 count=1048576

• Change the permissions so that only root can change the file.

  $ sudo chmod 600 /swapfile

• Make this file a swap partition.

  $ sudo mkswap /swapfile

• Enable this swap partition (start using it).

  $ sudo swapon /swapfile

Now you can check in htop if you have a swap partition and and if you are making use of it.

Remember these changes you have just made to the system are temporary. So after restart you won’t see the swap space of 1Gb.

In order to make it persitiant. You need to edit the file /etc/fstab. Add following entry to /etc/fstab.

/swapfile    swap    swap    defaults 0 0

Let’s see what this entry does.

• /swapfile is the file that we will be using.
• swap is the device mount point.
• swap specifies the file system type.
• defaults this is the filed for mount options.
• 0 specifies the option to be used by the dump program.
• 0 specifies the fsck command option.

Once you have this entry for swapfile in /etc/fstab you can reboot the system and check if the swap space is being used or not.