[sheepdog-users] sheep and no compression object files putted on btrfs & zfs

[Marcin Mirosław]

Hi!
I'd like to reanimate my old question. I put sheep on btrfs mounted with
compress-force=lzo. Files created manually (using dd from /dev/zero) are
compressed very well on this filesystem, as expected. When I create vdi,
write zeroes to vdi then disk usage on btrfs grows at the same level as
summary size of files created by sheep.
It means that btrfs, even with compress-force, doesn't compress files.
What is the reason of this behavior? How can I change it and allow btrfs
to compress files?
I did test on zfs, it works corrrectly, zfs compressed files without
problem.

Marcin