tl;dr: If you've installed btrfs-progs from testing (0.19.20120904-5), please downgrade to the version in core. If you regenerated your initramfs while this testing package was installed, please regenerate your initramfs after downgrading. Tom, My multi-device btrfs VM doesn't boot with this package. You've removed our own 70-btrfs.rules which calls btrfs device scan. Despite what Kay thinks, the builtin he wrote doesn't do the same thing, and leaves devices unassembled. Regardless, the initcpio hook wasn't modified to include the new rule and just errors out on the missing 70-btrfs.rules. I'm a little wary of making this change so soon when systemd in testing is already completely borked on i686 (which means that even if this package worked, it could still break boot for i686). For now, I've nuked the package in testing for both i686 and x86_64. d