Changing the Linux Swapfile Size

I am having real problems keeping my ASUS netbook running. It doesn’t have enough specs to run a lightweight version of Linux.

Increasing the size of the swapfile is supposed to improve the performance of low specced machines.

I have worked out how to change the swapfile size in the hope that it may help.

To check if you actually have a swapfile.

    swapon -s

This will either return nothing or detail the swapfiles statistics. In my case.

/swapfile file 512M 0

I have a 512 Mb swapfile and 0 Mb is being used.

I need to increase the size of the swapfile so the first thing is to turn off the swapfile.

    sudo swapoff -a

Once I do this I have to remove the current swapfile.

    sudo rm -i /swapfile

In general you want to create a swapfile that is twice the size of your RAM. My RAM is 2 Gb so I need to create a 4 Gb swapfile.

    sudo dd if=/dev/zero of=/swapfile bs=1M count=4096

Set file permissions.

    sudo chmod 600 /swapfile

Verify the permissions.

    ls -lh /swapfile

-rw——- 1 root root 4.0G Aug 27 16:59 /swapfile

We can see that only root user has the read and write flags enabled.

Mark the file as swap space by typing.

    sudo mkswap /swapfile

We then enable the swap file.

    sudo swapon /swapfile

Verify that the swap is available and confirm 4 GB RAM and 8 GB swap by typing.

    free -h

	total	used	free	shared	buff/cache	available
Mem:	1.8Gi	436Mi	778Mi	30Mi	655Mi	1.3Gi
Swap:	4.0Gi	284Mi	3.7Gi

Make the swap file permanent.

First back up the /etc/fstab file in case something goes wrong.

    sudo cp -pv /etc/fstab /etc/fstab.bak

Edit /etc/fstab in your text editor.

    sudo gedit /etc/fstab 

Add this line in /etc/fstab and confirm that there are no other “swap” lines.

    /swapfile   none    swap    sw  0   0

Now, reboot your system and then check that the swapfile is still there.

    free -h

	total	used	free	shared	buff/cache	available
Mem:	1.8Gi	336Mi	878Mi	30Mi	655Mi	1.3Gi
Swap:	4.0Gi	184Mi	3.8Gi

The swapfile has been permanently increased.

This is a copy of my /etc/fstab file.

    # /etc/fstab: static file system information.
    #
    # Use 'blkid' to print the universally unique identifier for a device; this may
    # be used with UUID= as a more robust way to name devices that works even if
    # disks are added and removed. See fstab(5).
    #
    # <file system>             <mount point>  <type>  <options>  <dump>  <pass>
    UUID=76EF-29F0                            /boot/efi      vfat    umask=0077 0 2
    UUID=046ce35e-f04a-41d8-ab8e-d5adcd58424e /              ext4    defaults   0 1
    /swapfile none swap  sw  0 0