Increase Swap Size

swapon --show

It will show the current swap available. If you see the type file, it indicates that you are using a swap file.

Now before you resize the swap file, you should turn the swap off. You should also make sure that you have enough free RAM available to take the data from swap file. Otherwise, create a temporary swap file.

You can disable a given swap file using this command. The command doesn’t produce any output and it may take a few minutes to complete:

sudo swapoff /swapfile

Now use the fallocate command in Linux to change the size of the swap file.

sudo fallocate -l 4G /swapfile

Make sure that you mark this file as swap file:

You should see an output like this where it warns you that old swap signature is being wiped out.

Once you do that, enable the swap file:

That’s it. You just increased the swap size in Ubuntu from 2 GB to 4 GB. You can check swap size using the free command or the swapon --show command.

You see how easy it is to resize swap size thanks to the swap files. You didn’t touch the partition, you didn’t reboot the system. Everything was done on the fly. How cool is that!

 Increase Swap Space on Linux Ubuntu

Check the System for Swap Information

We will first check the system which already has the swap space. We can have multiple swap files or partitions.

Please note that, we can see the swap available in the system by using the below command –

# sudo swapon --show

[sudo] password for ubuntu:

NAME TYPE SIZE USED PRIO

/dev/dm-1 partition 1020M 0B -1

Or we can use free -h command to display the swap space.

$ free -h

total    used    free    shared    buffers    cached

Mem:     975M    254M    720M       4.8M       12M    133M

-/+ buffers/cache: 109M 866M

Swap:    1.0G    0B      1.0G

We can see the Swap row in the output of the machine. Here in this machine we have 1.0 G swap space allocated.

Checking the Available Space on the Hard Disk Partition

The most common way of allocating the swap space on the Linux is to use the separate partitions allocated for the swap. We cannot alter the partition scheme which is impossible, but we can easily create a swap file that resides on the existing partition.

Before we do this we will check the current disk space by using below command.

$ df -h

Filesystem    Size    Used    Avail    Use%    Mounted on

The device under the /dev is the hard disk drives here we have 15 G space available.

In general, the amount equal to or double the amount of RAM on the machine is recommended for a good starting.

Creating a Swap File

As we know the available hard disk space, we can go head by creating a swap file within our filesystem. Also, note that, a file of the swap size which we are calling as ‘swapfile’ is in our root partition / directory.

The best way to create a swap file is by using a file called ‘fallocate’ program, this command will creates a file of a pre-allocated size instantly.

As we have 1 GB RAM allocated to our machine we will create more 2 GB file to meet the minimum requirement of the Linux.

$ sudo fallocate -l 2G /swapfile

We can verify that using the below command.

$  ls -lh /swapfile

-rw-r--r-- 1 root root 2.0G May 16 12:52 /swapfile

AD

Enabling the Swap File to Use

We have created the swap file of our requirement but it needs to be turned on in this swap space. Before we turn on the swap file, we needed to lock the permissions of the file to only root users privileges who can read the contents of the files which will prevents the normal users from being able to access the file.

We can do this using the below command

$  sudo chmod 600 /swapfile

To verify the permissions we can see using the below command

$  ls -lh /swapfile

-rw------- 1 root root 2.0G May 16 12:52 /swapfile

We can turn on the ''swapfile'' to use as swap space by using the below command

$ sudo mkswap /swapfile

Setting up swapspace version 1, size = 2 GiB (2147479552 bytes)

no label, UUID=049218ad-50b4-4c78-98e4-7a1ea21ca77e

We have to verify that the swap is available with the amount of space allocated. For this, we can use below command –

$ sudo swapon --show

NAME       TYPE       SIZE    USED    PRIO

/dev/dm-1 partition   3068M    0B       -1

OR Use the following command –

$ free -h

total    used    free    shared    buffers    cached

Mem:     975M    255M    720M       4.8M       12M    133M

-/+ buffers/cache: 108M 867M

Swap:    3.0G    0B    3.0G

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Making the Swap File Permanent

As we have changed in swap file for the current session, we also need to reboot the server that will not retain the swap settings to this permanant setting. Also, automatically we can add this swap file settings to ‘/etc/fstab’ file.

$ sudo vi /etc/fstab