Change swap size in Ubuntu

Starting with Ubuntu 17.04, the swap partition is replaced with a swap file, which makes it easy to be resized.

NOTE: Most of the commands below will require root privilege.

You can check your current swap size with

swapon -s

or

free -h

By default, the swapfile is /swapfile with file mode 600 and it belongs to the root user.

ls -lh /swapfile

If you want to resize your swapfile, it’s simple. The steps are

1. Disable the current swap file:

   swapoff -a
   

2. Change the size of the swap file. There are two possible ways, you can choose either of them

   1. Use the command dd

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

      This will allocate 4GB in total(each block is 1MB and there are 4096 blocks) to /swapfile.

   2. Use the command fallocate

      fallocate -l 4G /swapfile
      

      This will also allocate 4GB to /swapfile.

3. Make sure the file mode is 600 by

   chmod 600 /swapfile
   

   The output of ls -lh /swapfile should be like

   -rw------- 1 root root 4G May 23 19:48 /swapfile
   

4. Make the newly created swap file useable by

   mkswap /swapfile
   

5. Activate the swap file

   swapon /swapfile
   

6. Add swap setting to your /etc/fstab by adding(if this line does not exist) this line

   /swapfile none swap sw 0 0
   

If you want to disable the swap file in your system, it’s also very simple.

1. Disable the swap

   swapoff -v /swapfile
   

2. Delete(or comment) the swap line in /etc/fstab

   /swapfile none swap sw 0 0
   

3. Remove the actual swap file

   rm -v /swapfile