Currently init scripts strives to load dm-mod module. That's not enough and multipath is not working with dm_mod only loaded: ~ # lsmod | grep dm_ dm_mod 76157 0 ~ # multipath -v0 Apr 26 10:26:45 | DM multipath kernel driver not loaded This causes multipath failure on start. dm-multipath driver should be loaded instead. dm-mod is dependency of dm-multipath and will be loaded automatically: ~ # modinfo dm-multipath filename: /lib/modules/4.4.6-gentoo/kernel/drivers/md/dm-multipath.ko license: GPL author: Sistina Software <dm-devel@redhat.com> description: device-mapper multipath target depends: dm-mod intree: Y vermagic: 4.4.6-gentoo SMP mod_unload As for multipath selectors, as I see they are loaded automatically once configured in /etc/multipath.conf (and here https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=806443 is another confirmation that this happens). So simple patch for multipath init script will do the job: - [ -e /proc/modules ] && modprobe -q dm-mod + [ -e /proc/modules ] && modprobe -q dm-multipath
Fixed in tree: https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=e78d65c9e9ffa54a6bece600c8d09881361c4889