Любопытно, что GRUB может загружать ОС с ZFS снапшота: "On ZFS filesystem the first path component must be volume‘@’[snapshot]. So ‘/rootvol@snap-129/boot/grub/grub.cfg’ refers to file ‘/boot/grub/grub.cfg’ in snapshot of volume ‘rootvol’ with name ‘snap-129’. Trailing ‘@’ after volume name is mandatory even if snapshot name is omitted." https://www.gnu.org/software/grub/manual/html_node/File-name-syntax.html#File-name-syntax