What is a Swap Partition ?
A linux swap partition is like an overflow for your system’s RAM. If your RAM gets full, then your swap partition will run the other applications. So does this mean this is a great alternative to having a large RAM ? No ! because a swap partition on a hard drive can never be as fast as a RAM from a hardware point of view. Even with the growing popularity of Solid State Drives (SSD), they still cannot match the hardware capabilities of a RAM.
Step 1 : Check for any existing swaps
sudo swapon -s
This should show an empty list like :
FileName Type Size Used Priority
If you see an empty list like this, it means there is no swap currently on your system.
Step 2 : Create the Swap
Now that we have established that there is no previous Swap on the server, we will now check whether or not there is any space available for the swap on the server, by running the following command :
This command will show the memory stats for the server (in GB). Something like this :
Filesystem Size Used Avail Use% Mounted on /dev/vda1 20G 9.6G 9.1G 52% / none 4.0K 0 4.0K 0% /sys/fs/cgroup udev 235M 4.0K 235M 1% /dev tmpfs 50M 356K 49M 1% /run none 5.0M 0 5.0M 0% /run/lock none 246M 0 246M 0% /run/shm none 100M 0 100M 0% /run/user
After confirming that we have enough space on the server for a swap, we now create the swap using the ‘dd’ command :
sudo dd if=/dev/zero of=/swapfile bs=1024 count=1024k
This creates a swap of 1 GB on the server, in the file name ‘swapfile’, and should return an output like :
1048576+0 records in 1048576+0 records out 1073741824 bytes (1.1 GB) copied, 4.35649 s, 246 MB/s
We need to now create a linux swap area
sudo mkswap /swapfile
This command should output like :
Setting up swapspace version 1, size = 1048572 KiB no label, UUID=3e7247a1-d330-4c34-833c-a3020d99d25c
Step 3 : Activate the Swap
To activate the swap we need to run the following command :
sudo swapon /swapfile
Now check if the swap has been succesfully created and activated
Filename Type Size Used Priority /swapfile file 1048572 0 -1