I want to create swapfile of 8gb.
Swapfiles in btrfs require special handling.
You need to create a new subvol to hold the swapfile, create the swapfile as normal and then disable compression and copy-on-write on the swapfile.
More detailed instructions are here: https://wiki.archlinux.org/title/btrfs#Swap_file
I have btrfs filesystem.how do I create swapfile of 8gb
Not too sure how to if your system is already installed, there might be something here
https://wiki.archlinux.org/title/btrfs
If you are doing an install however you can create the partitions manually, I can tell you how to do this
… and you should ask the question public as a Thread not asking for private support, as this will not be visible for other users with the same issue later on …
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moved this as a public topic so everyone can join helping you 
@syed
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As we talked before on PM at telegram you have a BTRFS install with automatic setup for BTRFS subvols without any swapfile or partition.
So what needs to be done is:
- creating a subvol (BTRFS) for holding the swapfile
- creating the swapfile
- creating entries for grub and fstab
But someone else could help out here as I am not that familiar with BTRFS.
I just work on that script over here, but still not 100% sure about all the steps:
https://raw.githubusercontent.com/endeavouros-team/snippets/main/BTRFS-resume-creator
Would be nice to get some help on both tasks
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and sorry @dalto i made a little mess with my attempt to move this I think
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Pretty sure it was a mess before that.
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i am also not sure if poster will reach here at all may simply will go to reinstall with ext4 …
I wonder if the swapfile shouldn’t reside in a subvolume on it’s own, like @swap or @swapfile ?
The proper way to initialize a swap file is to first create a non-snapshotted subvolume to host the file
Here is an example of a setup that I did once. However I have never tried so far to make hibernation work on it.
BTRFS swapfile
1. sudo btrfs subvolume create @swap ## at the root of the BTRFS partition
2. sudo mkdir /swap
3. sudo mount -o subvol=@swap /dev/XXX /swap ## replace XXX with your actual partition for example sda2, nvme0n1p2
4. cd /swap
5. sudo truncate -s 0 swapfile
6. sudo chattr +C swapfile
7. sudo btrfs property set swapfile compression none
8. sudo dd if=/dev/zero of=swapfile bs=1M count=512 status=progress
9. sudo chmod 600 swapfile
10. sudo mkswap swapfile
11. sudo swapon swapfile
12. Now Edit the /etc/fstab and add the following two lines:
UUID=NNNN /swap btrfs subvol=@swap ## replace NNNN with the UUID of the partition where @swap resides
/swap/swapfile none swap defaults 0 0
Do you also have a dedicated subvolume for the swapfile?
It should if you want to take snapshots. You can’t take snapshots of the subvolume holding the swapfile.
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this is what I say before
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I need to get a new pair of
BTW, I am following the steps to set up the hibernation, manually 
I just finished mkinitcpio -P.
I’ll try to hibernate and report.
I am not getting it quite right:
$ systemctl hibernate
Failed to hibernate system via logind: Not enough swap space for hibernation
I should probably post in a new thread.
you can stay here as it will help anyways to see how it works
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i just tested the scripts here on two installs and I see that it is working for encrypted BTRFS swapfile install… but the one for unencrypted has some issue getting the UUID for the root device.
if encrypted I can use:
sudo blkid -o device | grep luks to get the needed UUID for resume= but this is indeed not working for unencrypted…
what command would help to get the UUID there?
resume=UUID=e2bf9de5-77fb-4f71-ah1e-88ea14d46955
so it would be what I see in /etc/fstab for root device:
UUID=e2bf9de5-77fb-4f71-ah1e-88ea14d46955 / btrfs ***
what can be identified by the / ?
I suspect this was my issue as well.
findmnt / -o UUID -n
?
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