Linux uses Swap Space to back its physical memory with an overflow area. In most cases the suggested amount is a disk space equal to the amount of physical memory you have installed. You don’t want your system to ever run out of RAM+swap, but you usually would rather have enough RAM in the system. So twice the size of RAM doesn’t need to swap.
The free -m command shows that the swap memory in your current server.
We can increase 4GB of swap size now.
Create Swap file
touch /swapfile
Use the following command to create 4GB of swap file.
# dd if=/dev/zero of=/swapfile bs=1M count=4096
if=/dev/zero : Read from /dev/zero file. /dev/zero is a special file in that provides as many null characters to build storage file called /swapfile. of=/swapfile1 : Read from /dev/zero write stoage file to /swapfile. bs=1M : Read and write 1M at a time. count=4096 : Copy only 4096 input blocks. This will create a new partition with 4GB space. To make it a swap partition you need to execute the following command.
# mkswap /swapfile
Now the swap file is created.
activate /swapfile file swap space now.
# swapon /swapfile
Add entry on /etc/fstab file to activate after Linux system reboot.
# vi /etc/fstab
/swapfile swap swap defaults 0 0
save and close the file.
Now check your swap space now.
# free -m
In order to delete swap.
Run “swapoff /swapfile” command
Remove the entry from /etc/fstab file
Remove /swapfile file (using rm command)