Right, you are good to do swap files on btrfs since linux 5.0 or so as long as you follow some rules. Disko thankfully covers all those details for you, but I shouldn't have skipped over that in the piece. I'll make an update when I get a chance.
Swap files work, but I wouldn't quite say "you are good to do swap files on btrfs" because the official documentation (the page I linked earlier) says
> filesystem - must be only single device
> This means swapfiles will have an amplified impact, much larger than the size of the swapfile itself.
> Users should be aware of the impact when using swapfiles alongside other data. This is especially discouraged for root filesystem.
If a swap file is the only thing that will work with your setup, then it's fine to use one, but if you're at all able to use a swap partition, then that's a far better choice. (Swap files are fine on ext4 and xfs; it's only COW filesystems like btrfs and zfs where they should be avoided.)
While everything else is pretty obvious from the nature of an unmovable file, "scrub will skip those block groups which have extents of an active swapfile on them, and those block groups may also contain extents belonging to other files".
Then again, I mostly use XFS, which has no data checksums at all, so YMMV.
gucci-on-fleek · · focus · HN ↗
[0]: <a href="https://btrfs.readthedocs.io/en/latest/Swapfile.html" rel="nofollow">https://btrfs.readthedocs.io/en/latest/Swapfile.html
ciferkey · · focus · HN ↗
gucci-on-fleek · · focus · HN ↗
> filesystem - must be only single device
> This means swapfiles will have an amplified impact, much larger than the size of the swapfile itself.
> Users should be aware of the impact when using swapfiles alongside other data. This is especially discouraged for root filesystem.
If a swap file is the only thing that will work with your setup, then it's fine to use one, but if you're at all able to use a swap partition, then that's a far better choice. (Swap files are fine on ext4 and xfs; it's only COW filesystems like btrfs and zfs where they should be avoided.)
jasomill · · focus · HN ↗
Then again, I mostly use XFS, which has no data checksums at all, so YMMV.