Hey @rustybird ! Didn’t know you were file-reflink maintainer. Good to know!
If the present thread is about compression (which end goal is lower space consumption amongst other things, like reduced writes and faster reads) i have been interested in pool deduplication for a really long time, to finally find bees, but not found it compiled for recent version even on copr for fedora (dom0…) and built only for opensuse…
Pulled qubes-builder, tried to use it to build bees for Q4.2, didn’t reach make qubes. Gave up pet project.
Would be nice if someone could do the magic for bees to land in unstable repos to be tested on Q4.2. I would gladly open a thread on testing section if that happens and restore all my qubes which are mostly build caches for Heads project on different OSes (debian 10, 11, 12and nix templates specialized for different things, with minimal-debian for builds up to fully blown full of junk templates… Which would show massive deduplicate as proof of concept, proving worth of going that path im pretty sure!)
Interested?
I would really love to have your input on that!
If compression is interesting, i continue to believe that deduplication on the pool level makes so much sense for Qubes. Just looking at my wyng-backups deduped backups archive stats (whonix templates are 60% similar) and my clones of everything (no cost but diffs) until I use wyng to restore previously deleted local volumes (unless i manually clone a similar qube to restorr with wyng --sparse-write directly into thr thin lvm volume to onky wriye changes to keep duplication low), other full volume restoration or clones grow big after rhey are cloned and currently take all my pool from which i swap qubes in and off (and where dedup on write from the pool would save my days because i wouldn’t need do that anymore!)
Recommendation from @brendanhoar at Pool level deduplication? - #21 by brendanhoar
(Where i invite you to participate in that thread with your knowledge, of course!!!)
One last time. 
Please please please push spec file for builder to have bees dropped under Q4.2 unstable repo?
Brtfs deduplication docs: Deduplication — BTRFS documentation
Most recent copr (8 months old 7.2 release is not good enough for fedora 37):
https://copr.fedorainfracloud.org/coprs/proletarius101/bees/builds/
Edit: found src rpm
https://rpmfind.net/linux/RPM/opensuse/tumbleweed/x86_64/bees-0.9.3-1.2.x86_64.html
Will try to rpmbuild on fedora 37 template I guess
Spec file Show openSUSE:Factory / bees - openSUSE Build Service (4 months old)
If that happens, i will follow guidance from tasket and restore my vms on Q4.2 on brtfs Restore lvm backups on brtfs? · Issue #166 · tasket/wyng-backup · GitHub (thanks @tasket !)