Ubuntu 18.10 hibernation

Question

Somehow I could install Ubuntu 18.10 without creating any SWAP partition nor I seem to have a SWAP file. I wonder if I still could get hibernation to work, without having both of them. I tried already creating a SWAP-file and hibernate with it, but that did not work.

Is there a way around the SWAP file and get hibernation running?

I don't think you can totally eliminate the swap - this is where Ubuntu stores the contents of RAM when it goes into hibernation. — Charles Green, Feb 15 '19 at 14:33
@VeeJay as written I already tried to create a SWAP file without success of hibernation. The system woke up but got stuck when reloading everything. — SnowGepard, Feb 15 '19 at 14:38
@CharlesGreen thats what I thought, just wonder how systems like OSX realize that without a swap file, but maybe they have one which they delete after waking up. Is there a similar option in Ubuntu, since I do not want to have a file of at 64Gb of size taking up space on my drive. — SnowGepard, Feb 15 '19 at 14:40
How do you figure a 64G swap file? How much RAM do you have? — heynnema, Feb 15 '19 at 14:49
This is a bit dated, but probably still valid http://osxdaily.com/2010/10/11/sleepimage-mac/. On Windows, the file is "hiberfil.sys" — Charles Green, Feb 15 '19 at 15:40
I have 32Gb RAM on my system. Usually I followed the rule with 2x RAM but I guess this is not needed anymore in times of SSD. I need at least a 38Gb swapfile according to https://help.ubuntu.com/community/SwapFaq — SnowGepard, Feb 23 '19 at 13:35

score 1 · Answer 1 · answered Feb 15 '19 at 15:36

1

I fear creating a SWAP file is your only option. Your RAM state needs to be held somewhere on the disk while power is off. Maybe you created too small SWAP – it is recommended to have the SWAP space at least as big as your RAM (+ some small reserve). I have Ubuntu 18.10 with 16 GB of RAM and 19 GB of SWAP file and it works well.

Nevertheless, it seems you didn't tell the system it should use SWAP to resume from hibernation. Modify /etc/default/grub (sudoedit /etc/default/grub), edit the line GRUB_CMDLINE_LINUX_DEFAULT and put there parameters resume (with your /dev/ UID of partition having the SWAP file) and resume_offset with the starting value of physical_offset of this swap.

(You'll get this value by checking output of sudo filefrag -v /swapfile | head.)

Finally, reload by sudo update-grub.

For more thorough answer about setting GRUB, see an excellent section Hibernation using a swap file: How can I hibernate on Ubuntu 16.04?

Tell us if you succeeded.

answered Feb 15 '19 at 15:36

Edvard Rejthar

249

1

Thanks for you answer. I will test this as soon as possible but the last time I did not tell Grub to use it. – SnowGepard Feb 18 '19 at 17:10
I just tried to follow the steps given here [https://askubuntu.com/questions/768136/how-can-i-hibernate-on-ubuntu-16-04]. But with the first command grep swap /etc/fstab I get back /swapfile none swap sw 0 0 which does not help a lot. I know that I have a swap file right now of 2Gb of size, which is way to less for my system. – SnowGepard Feb 19 '19 at 09:55
I tried the option with the swapfile and increased the size to 38Gb, since my system has 32Gb RAM. It did not work. I followed this manual https://www.linuxuprising.com/2018/08/how-to-use-swap-file-instead-of-swap.html, but without changing '/etc/initramfs-tools/conf.d/resume' since this file does not exist on my system. It does not work and I am not sure how to continue without breaking initramfs. – SnowGepard Feb 23 '19 at 10:36

ciampix · Accepted Answer · 2019-02-15T17:59:53.733

Yes you can find answers elsewhere searching for hibernate + linux + file but I post the super-short answer:

sudo filefrag -v /swapfile |grep " 0:"| awk '{print $4}'

in my system for example it gives: 57643008.. (for the sake of curiosity this is the offset of the swap file the file system...) put away this number (we will use it later) and find another number:

lsblk -o UUID,MOUNTPOINT

in my system for example it gives:

0ec9c519-c7ec-43e3-b812-967d81842458 /home

eb343dae-82e4-4155-9026-18c891d3252b /

since the swap file is in / it is this the UUID of interest. Then add to /etc/default/grub:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash resume=UUID=eb343dae-82e4-4155-9026-18c891d3252b resume_offset=57643008"

sudo update-grub

and you are done (use your UUID and OFFSET numbers obviously). Test it with the command:

sudo hibernate

PS: according to some kernel docs that I can't find now, it should be sufficient a swap file of half of your RAM size or less (they say 2/5). Check with: cat /sys/power/image_size

In combination with https://linuxize.com/post/how-to-add-swap-space-on-ubuntu-18-04/ this solved my question. Now I just need to figure out how to add the option back in the power menu, so that I can select that the laptop goes into hibernation when not plugged in and I close the lid. — SnowGepard, Mar 15 '19 at 08:42

Ubuntu 18.10 hibernation

2 Answers2