Swap Space Made Easy

Swap Space Made Easy Cutting through the exposition and explanation, we can create a new swap file as easily and quickly as this: sudo dd if=/dev/zero /of=/swapfile2 bs=1024 count=104857 sudo mkswap /swapfile2 sudo chmod 600 /swapfile2 sudo swapon /swapfile2 And let’s check that it worked: swapon --show sudo dd if=/dev/zero /of=/swapfile2 bs=1024 count=104857 in a terminal window If you want to make that permanent drop, it into your /etc/fstab file. The line we need to add to the bottom of the file is: /swapfile none swap sw 0 0 The operating system makes use of swap space when its available physical memory (RAM) is running out due to ever-demanding applications. In this situation, the operating system moves the inactive pages in physical memory to swap space. This freeing up of physical memory will be used for other applications. When the physical memory is available enough, the swap memory area will be brought back to the physical memory. The administrators ensure that sufficient swap space present in the system so that some free physical memory always available to the operating system. This article provides steps to create or increase swap space and also delete if you need it. Table of Contents ​Do I really need swap space? Partition or file? What is the recommended swap size? Creating swap space Disable and remove a swap file Limitation ​Conclusion ​Do I really need swap space? Not always, the provided system has a large amount of physical memory (RAM). But it is recommended to have swap space handy. The system may crash when the system is run out of physical memory when many applications are running with large memory footprint. When compared to RAM, disk space is relatively cheap! Partition or file? Swap space can be a dedicated swap partition (recommended), a swap file, or a combination of both. By default, most of the Linux distributions create a dedicated swap partition or a file on the system partition during installation. Windows operating system generally has the swap space as a file. What is the recommended swap size? Though there is no hard and fast rule to have swap space, it is recommended to have at least 1.5 times the physical memory. In the case of hibernation, the swap partition should be at least as big as the RAM size. Creating swap space Following are the instructions to create swap space using a file: Login as root. sudo su get superuser ubuntu linux Create swap file in directory “/var” with name “swapfile”. At the shell, create the file and set root permissions as follows: cd /var touch swapfile chmod 600 swapfile ls -la swapfile create swap file Use “dd” command to fill the swap file with 1 GB size (as an example) as follows : dd if=/dev/zero of=/var/swapfile bs=1024k count=1000 create swap file with data Now setup the swap file: mkswap /var/swapfile Picture Enable the swap file: swapon /var/swapfile enable swap file To check whether the new swap file was successfully created, either of the below commands can be used.​ # cat /proc/swaps # swapon –show get all swap files Add below line to the “/etc/fstab” file so that next time when the system boots, it enables the newly created swap file: /var/swapfile none swap sw 0 0 Disable and remove a swap file Disable the swap file. # swapoff /var/swapfile Delete the swap file. # rm /var/swapfile Remove the entry from “/etc/fstab” file. /var/swapfile none swap sw 0 0 Limitation