How to create swap file on ext4

Question

My friend whats to create a 4GB swap file on his ext4 file system. because he is using a chromebook acer c7 the way he installed he did not have a chance to specify swap partition

and now he want to create a swap file on his file system.

This is the guide he is following

http://ubuntuforums.org/showthread.php?t=1618220&p=10098565#post10098565

First you have to create a 2GiB file, for example in /mnt:

sudo dd if=/dev/zero of=/mnt/swap bs=1M count=2048

Then format the file to swap:

sudo mkswap /mnt/swap

Add the swap file to the system:

sudo swapon /mnt/swap

Check it out, i.e.:

free -m

Edit the fstab file:

gksu gedit /etc/fstab

and add this line at the end of the file:

/mnt/swap  none  swap  sw

Save the file and exit. That's all.

This is what he is getting

enter image description here

user@chrubuntu:~$ sudo swapon /mnt/swap
swapon: /mnt/swap: swapon failed: Invalid argument

and his fstab looks like this

fstab

any way to fix this ??

One more thing he is using ubuntu 14.04 and it is not a fresh install

Thank you for your time

Does he get the error you've mentioned both times he tries to run swapon, or just after he's added it to the fstab file? — jkt123, May 04 '14 at 21:25
@Levan the fstab file doesn't have the /mnt/swap none swap sw at the end of the file. Save the file after editing. — Elder Geek, May 04 '14 at 21:27
Thank you for the reply he follows the above guide that i mantioned
before this step every thing works Add the swap file to the system:

sudo swapon /mnt/swap

http://imgur.com/rFP0gbc — Levan, May 04 '14 at 21:30
Is this system running a custom kernel? What does uname -a show? — psusi, May 04 '14 at 22:47
@psusi Thank you for the reply again this is what it say ser@chrubuntu:~$ uname -a Linux chrubuntu 3.4.0 #1 SMP Fri Apr 11 19:07:10 PDT 2014 x86_64 x86_64 x86_64 GNU/Linux user@chrubuntu:~$ — Levan, May 04 '14 at 22:52
@psusi I have a question, what do you think if he manually upgrades to the latest kernel?? will his chrome book still boot or it is too dangerous — Levan, May 04 '14 at 23:05
I don't know enough about it, but it certainly appears to have a custom, older, kernel, but if you check its config file in /boot, you may find that it was built without CONFIG_SWAP, so doesn't support swap. — psusi, May 05 '14 at 02:07
@psusi thank you you have been tremendous help, crazy thing is that he can not even upgrade to a newer kernel — Levan, May 05 '14 at 11:16

Elder Geek · Answer 1 · 2014-05-04T23:01:45.997

1

It's possible the problem is because it's in the /mnt directory or it could be a security issue world readable swap isn't great. Try this tutorial and see if you have better results.

http://www.cyberciti.biz/faq/linux-add-a-swap-file-howto/

edited May 04 '14 at 23:01

answered May 04 '14 at 22:01

Elder Geek

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Thank you for the reply I will tell him and notify you about the result – Levan May 04 '14 at 22:04
Small preamble this is the UUID=c8a5817e-90d3-48f3-976a-8e80de5e6a4b he got this is the command he used sudo swapon -U c8a5817e-90d3-48f3-976a-8e80de5e6a4b and sadly this is what terminal told him swapon cannot find the device – Levan May 04 '14 at 22:21
1

@Levan please provide the output of ls -a /mnt – Elder Geek May 04 '14 at 22:27
1

@Levan please provide the output of the command ls -a /mnt we are missing the ls – Elder Geek May 04 '14 at 22:35
sorry @Elder Geek small mix up this is what he got user@chrubuntu:~$ ls -a /mnt . .. swap user@chrubuntu:~$ I do not understand did not the terminal say that it created a file ?? – Levan May 04 '14 at 22:41
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That's definitely not going to work; uuid recognition only works on partitions, not files. – psusi May 04 '14 at 22:42
@psusi any suggestions ??? and thank you fore the reply – Levan May 04 '14 at 22:43
1

@Levan just double-checking – Elder Geek May 04 '14 at 22:45
@Elder Geek thank you very much for the help/time/afford – Levan May 04 '14 at 22:46

score 0 · Answer 2 · answered Feb 27 '18 at 15:59

swapon failed: Invalid argument

Based on this discussion and this post, most likely your file system doesn't support swap files.

You need to create it somewhere outside of /mnt, as part of the native filesystem (e.g. in /var).

Try following these steps instead.

How to create swap file on ext4

2 Answers2