How to increase swap space?

Question

I have, by default, 250MB of swap space in Ubuntu, and I want to expand it to a larger size. I need 800MB, which I think will be enough to open several applications without having to hit the current limit of swap. I hope someone can help me.

Answer 1

You can always create a swap file to add more swap space. This is not the same in every aspect as swap partition, but it will be easy and dynamic.

In the following steps, change /media/fasthdd/swapfile.img to anything you like. For example, it can be /swap.img as well. /media/fasthdd/swapfile.img is just an example filename. If you are using this one, then of course there must be a directory /media/fasthdd/ with enough free space for your new swap file.

Use any terminal application to run the commands of the following steps. All commands should be run with root privileges. To do this, you can either add sudo to the beginning of every command or run sudo bash before running the commands.

1. Create an empty file:

   This file will contain virtual memory contents so make file big enough for your needs. This one will create a 1GiB file, which means +1GiB swap space for your system:

   dd if=/dev/zero of=/media/fasthdd/swapfile.img bs=1024 count=1M
   

   If you want to make a 3GiB file, then change count value to count=3M. See man dd for more information.

2. Bake the swap file:

   The following command is going to make a "swap filesystem" inside your fresh swap file.

   mkswap /media/fasthdd/swapfile.img
   

3. Bring up on boot:

   To make sure that your new swap space is activated while booting up computer, you should add it to the filesystem configuration file /etc/fstab. Add it to the end of the file. This is recommended because other filesystems (at least one that contains a swap file) must be mounted in read-write mode before we can access any files.

   # Add this line to /etc/fstab
   /media/fasthdd/swapfile.img swap swap sw 0 0
   

4. Activate:

   You can either reboot your computer or activate the new swap file by hand with the following command:

   swapon /media/fasthdd/swapfile.img
   

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If everything goes well, you should see that more swap space is available for use. You can use the following commands to check your new swap and confirm that it is active:

$ cat /proc/swaps
Filename                           Type       Size    Used    Priority
/media/fasthdd/swapfile.img        file       8388604 2724    -1
$ grep 'Swap' /proc/meminfo
SwapCached:         4772 kB
SwapTotal:       8388604 kB
SwapFree:        8355812 kB

Answer 2

Resize Swap to 8GB

# Turn swap off
# This moves stuff in swap to the main memory and might take several minutes
sudo swapoff -a
Create an empty swapfile
Note that "1G" is basically just the unit and count is an integer.
Together, they define the size. In this case 8GB.
sudo dd if=/dev/zero of=/swapfile bs=1G count=8
Set the correct permissions
sudo chmod 0600 /swapfile
sudo mkswap /swapfile  # Set up a Linux swap area
sudo swapon /swapfile  # Turn the swap on

Check if it worked

grep Swap /proc/meminfo

Make it permanent (persist on restarts)

Add this line to the end of your /etc/fstab:

/swapfile swap swap sw 0 0

Answer 3

GUI method for increasing the size of swap partition

Another way to increase the swap size is to use the GParted partition Editor. In short, you resize the swap partition, then right click on it and choose "Swapon".

It's easier to boot gparted-live-disk or an Ubuntu live disk (so that the all /dev/sda partitions will be unmounted). If you run Ubuntu live disk in some versions before 18.04, you may need to install gparted by running the commands below:

sudo apt-get update
sudo apt-get install gparted && sudo gparted

You must be able to increase the size of swap partition only if there is an unallocated space present before or after the swap partition. If there was no unallocated space (the space which we are trying to add with swap partition) below or above the swap partition, then we have to resize the partitions and get that unallocated space.

Case 1 - unallocated space present before or after the swap partition

In the above screenshot, I had 11.4 GB of unallocated space before the linux-swap and 12.8 GB after the swap partition.

• To resize, right click on the swap partition (/dev/sda9 here) and click on the Resize/Move option. It will look like this:

  

• Dragging the slider arrows left or right then click on the Resize/Move button. Your swap partition will be resized.

---

Case 2 - unallocated space is between the partitions

In the above screenshot, the unallocated space which we wants to add to the swap partition was between dev/sda7 and /dev/sda8.To move the unallocated space from that to just above swap partition,we have to follow the simple steps given below,

• Right-click on the /dev/sda8 partition and click on Resize/Move option.

  

• click and move the slider to the extreme left,so that the unallocated space which was just above the /dev/sda8 partition will comes below /dev/sda8.After that click Resize/Move button.

• And now the unallocated space was just above to the swap partition which was like Case 1.Now follow Case 1.

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Case 3 - if the unallocated space was present outside the Extended partition)

I had an unallocated space of 18 GB just below to the extended partition.To add this space to the linux-swap partition(which was present inside the extended partition),we have to follow the below steps,

• Right-click on the extended partition and select Resize/Move option,it will be like the below screenshot

  

• Click and drag the arrow to the extreme right and click on Resize/Move,so that the unallocated space of 18 GB will comes at the bottom of extended partition.I had a 14.80 GB of unallocated space already present at the bottom and now the 18.34 GB combines with that to create unallocated space of (18.34+14.80 GB) at the bottom of the extended partition.

• Now there was an unallocated space just below to the swap partition,it will be like Case 1,then follow case 1.

NOTE: Don't forget to take backup of all your important datas before proceeding the above operations.

Answer 4

You can also use fallocate if you want to reserve space for your swapfile, without the need to fill the file with 0 through dd.

From the man page:

DESCRIPTION
   fallocate is  used to preallocate blocks  to a file.

   For filesystems  which support the  fallocate system
   call, this is done  quickly by allocating blocks and
   marking them  as uninitialized,  requiring no  IO to
   the data blocks. This is much faster than creating a
   file by filling it with zeros.

If you already have a swap defined, you can either remove it or keep it, and your *nix will manage it (even better with by defining a swapon priority). This could be usefull, in case you want to spread your swap between different devices, drive (based on their speed or other custom needs, see What is the purpose of multiple swap files on StackExchange).

Simple fallocate usage for adding a second swap file

Check swap situation:

$ sudo swapon -s
Filename                Type        Size    Used    Priority
/swapfile               file        262140  246276  -1

Create a 4G swap file

Standard way of creating and activating a swap file:

size="4G"
file_swap=/swapfile_$size.img
sudo touch $file_swap
sudo fallocate -l $size /$file_swap
sudo mkswap /$file_swap
sudo swapon -p 20 /$file_swap

One-liner:

$ size="4G" && file_swap=/swapfile_$size.img && sudo touch $file_swap && sudo fallocate -l $size /$file_swap && sudo mkswap /$file_swap && sudo swapon -p 20 /$file_swap

Make your swap permanent

Add a line in your /etc/fstab file so that swap will be initialized on the next reboot (we also update here the priority of the newly created swap space and we update the priority of the old swap file).

In your /etc/fstab file, notice the priority of the prev swap is now 10.

/swapfile    none    swap    sw,pri=10      0       0
/swapfile_4G.img     none    swap    sw,pri=20      0       0

Check swap situation after reboot:

$ sudo swapon  -s
Filename       Type     Size        Used    Priority
/swapfile      file     262140      0       10
/swapfile_4G.img       file     4194300     0       20

Remove one of the swap spaces (for example the original 256Mb)

Edit /etc/fstab

Remove the line related to the swap you want to remove.

Delete that swap

Delete and remove the swap file.

sudo swapoff /mnt/swapfile && sudo rm /mnt/swapfile

Resources:

• The official Ubuntu swap FAQ page

Answer 5

I found the following video very interesting and a straightforward approach to increase the size of swapfile. Checkout this short video tutorial: How to Increase Swap on Ubuntu Linux | Linux Handbook

(From this video) following is the way to increase the swap space (if your system is using swapfile):

First check the swap size of your linux system:

swapon --show

Sample output:

NAME      TYPE   SIZE USED PRIO
/swapfile file 797.2M   0B   -2

This output shows the swap size is being used and the type of swap. Here the swap type is "file" type (it could be partition type as well).Ubuntu uses swapfile by default and increasing and decreasing the size of it is fairly easy.

As we are going to modify the swapfile so at first turn it OFF. You might notice the process is being killed for multiple times. This happens because before turning the swap OFF the system moves its contents to main memory which may overflow the main memory. So, if the following command is killed, run it multiple times until it is successfully completed. You may also face sudden logout and / or other processes may be killed automatically.:

sudo swapoff /swapfile

Now if you run swapon --show it won't show anything as it is turned OFF.

Now change the swap size (I am making it 4GB, for n GB make it nG):

sudo fallocate -l 4G /swapfile

Now if you check the file you will see the size is increased. To see it:

ls -lh /swapfile

Now tell the Linux system to use this file as swap system:

sudo mkswap /swapfile

This will wipe the old swap signature and use the new one.

Now to turn the swap ON (as we initially turned OFF the swap space):

sudo swapon /swapfile

Done!

Now use swapon --show or free -h to see the change.

Answer 6

In my case I already had a swap file which I thought was 1GB but when I looked at it more closely it was only 256 MB big and when pre-compiling my rails assets the server would run out of memory

Errno::ENOMEM: Cannot allocate memory - nodejs

I created my swap file as described here: https://stackoverflow.com/a/34885004/784318

Now the line that creates an empty file called /swapfile is as follows:

sudo dd if=/dev/zero of=/swapfile bs=1024 count=256k

Now to resize the swapfile I had to do these simple steps:

# Reboot the system to be able to switch swapping off
sudo reboot

# Turn swap off
sudo swapoff -a

# Delete the `/swapfile`
rm -f /swapfile

# Recreate the swapfile but with double file size memory
sudo dd if=/dev/zero of=/swapfile bs=1024 count=512k

# Turn swap back on
sudo swapon -s

# Change the permission to non-world-readable
sudo chown root:root /swapfile 
sudo chmod 0600 /swapfile

# Use the swap file
sudo mkswap /swapfile
sudo swapon /swapfile

The file was created (536870912 / 1024 / 1024 = 512 MB):

ls -lia /swapfile 

768 -rw------- 1 root root 536870912 Apr 27 07:54 /swapfile

Using free -m command I could see that the file now is 512 MB like expected:

Answer 7

If you want to resize your swap partition and do not want to create a swap file, then

1. Boot Ubuntu installation media live session by choosing Try Ubuntu

2. Open GParted or other partition manager if you use Kubuntu, Lubuntu, etc.

3. Disable swap:

4. Resize main partition (In my case I was doing it for /dev/sda2) by shrinking it

5. Resize swap partition making it bigger

6. Enable swap using the same context menu and Swapon button

7. Reboot into usual Ubuntu session

8. Open terminal and see if swap size changed:

    $ sudo swapon --show
    [sudo] password for user: 
    NAME      TYPE      SIZE   USED PRIO
    /dev/sda3 partition   2G 129.3M   -2
   

It's not changed. To change it, do the next:

9. Disable swap:

    $ sudo swapoff /dev/sda3
   

10. Recreate swap:

    $ sudo mkswap /dev/sda3 
    mkswap: /dev/sda3: warning: wiping old swap signature.
    Setting up swapspace version 1, size = 10 GiB (10788794368 bytes)
    no label, UUID=2e315546-04f7-4db6-8ca9-25f36f4ee960
    

11. Enable swap:

    $ sudo swapon /dev/sda3
    

12. Check its size:

    $ free -m
                  total        used        free      shared  buff/cache   available
    Mem:          15948       13008         301         670        2638        2006
    Swap:         10288           0       10288
    

13. Check your swap partition's UUID:

    blkid | grep swap
    

14. Replace UUID in /etc/fstab file for swap partition by correct one:

    user@pc:~$ blkid | grep swap
    /dev/sda3: UUID="e434f979-8861-4bd3-888c-824de39d739a" TYPE="swap" PARTUUID="3ca528d4-db6c-4ed6-ae95-94729e3f609c"
    user@pc:~$ cat /etc/fstab | grep swap
    #UUID=add18f30-c662-4e5c-bfc7-62f4d012fb2e none swap sw 0 0
    UUID=e434f979-8861-4bd3-888c-824de39d739a none swap sw 0 0
    

    I've just commented older record and created a new record with the correct UUID from blkid command output.

Answer 8

How to add a swap file

1. Create .img file

    sudo dd if=/dev/zero of=/swap.img bs=1M count=1000
   

   note!: bs=1M count=1000 ==> 1GB
   (bs * count = size in megabytes )

   Other example:

   sudo dd if=/dev/zero of=/swap.img bs=10M count=100 
   

2. Format .img file

   sudo mkswap /swap.img
   

3. Enable swap file

   sudo swapon /swap.img
   

4. Add swap file to fstab
   Add this line to your fstab (/etc/fstab):

   /swap.img   none            swap    sw              0       0
   

Answer 9

I have zfs and this worked for me.

sudo zfs create -V 8G -b $(getconf PAGESIZE) -o logbias=throughput -o sync=always -o primarycache=metadata -o com.sun:auto-snapshot=false rpool/swap

sudo mkswap -f /dev/zvol/rpool/swap

sudo swapon /dev/zvol/rpool/swap

In /etc/fstab I added this line (with tabs as spaces):

/dev/zvol/rpool/swap none swap discard 0 0