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I just recently increased my RAM, so I wanted to increase the swap size too. I know Elementary OS is based off Ubuntu, so I've been following Ubuntu information since there isn't much documentation for this stuff for Elementary OS specifically. I have 8GBs of ram now, and from what I understand, Ubuntu recommends that you allocate 11GBs of ram if you're planning on using hibernation, or 3GBs if you're not using hibernation. Is this true for Elementary OS too?

https://itsfoss.com/swap-size/

Anyways, I was following the following guide to increase the swap size:

https://linuxhandbook.com/increase-swap-ubuntu/

But when I got to the part where we use the follocate command to increase the swap file size, I get the following error:

fallocate: fallocate failed: Invalid argument

I figured I'd allocate 11GBs of space just to be safe, so I was using the following command:

sudo fallocate -l 11G /dev/dm-2

Any ideas as to what I'm doing wrong here? Is 11GBs a good size for the swap for Elementary OS with 8GBs of RAM? Am I getting GiB mixed up with GB in the follocate command?

Thanks in advance.

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    Add the output of swapon --show. Swap can be a file or it can be a partition and that changes the steps you need to follow.
    – Maccer
    Oct 26 at 13:13
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Generally a swap file would not be written in /dev, which contains device APIs, but in the root (/) directory. So long as you don’t mind having a file there, you can do something like this:

sudo fallocate -l 12G /swapfile

Note: The 12G size is different from what you specified not because 11GB is “wrong”, but because I generally leave 4GB of swap for buffers on machines that need to hibernate. Feel free to set any value you are comfortable with.

From here it would be a good idea to verify the file exists and is the right size with:

ls -lh /swapfile

You should see a single file of the same size you specified in the fallocate command.

The next step is to enable the swap file. This is done by setting the permissions:

sudo chmod 600 /swapfile

Then marking the file as being for swapping purposes:

sudo mkswap /swapfile

If everything goes properly, you’ll see something like:

Setting up swapspace version 1, size = 12288 MiB (12884901888 bytes)
no label, UUID=6ecf2854-2ab9-4437-1ee0-577e740897ff

Now you can tell the system to use that space:

sudo swapon /swapfile

You can verify Elementary OS is using the swap file with the swapon command:

sudo swapon --show

You should see something like this:

NAME      TYPE   SIZE USED PRIO
/swapfile file 12288M   0B   -2

Finally, to make your swap file operational at boot time, you need to edit your fstab (File System Table) file:

sudo vi /etc/fstab

Note: Feel free to use any text editor you are familiar with. It does not need to be vi.

Add this to the end of the file:

/swapfile     none     swap    sw   0   0

While this looks like a lot of steps, it’s not too bad when you step through the process to see what’s going on 👍🏻

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  • Thank you for that detailed answer! I just have two questions. First, should I delete the old swapfile being used that was in /dev/dm-2? Second, in the fstab file, there is already a line that says "/dev/mapper/data-swap none swap defaults 0 0". Should I delete that line and replace it with the one you mentioned?
    – Link1600
    Nov 5 at 12:48
  • To answer your questions: (1) Yes, but only after you have disabled it and restarted the system (to ensure it's not being accessed) (2) If you do not have a swapfile at /dev/mapper/data-swap, then I would suggest first commenting out the line by adding a # to the very start. If nothing breaks, then you can delete the line 👍🏻
    – matigo
    Nov 5 at 13:20

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