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
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)