I have done this recently using Ubuntu 16.04.2 Server and Cobbler/PXE boot. The kernel options / boot string used is as follows:
biosdevname=0 net.ifnames=0 netcfg/choose_interface=eth0 netcfg/get_hostname=openstack-controller-node install disk-detect/multipath/enable=true
This detects the multipath disk and I can partition it fine but there seems to be a bug in grub because it is not installing to the multipath device leaving the server stuck with no way to boot.
EDIT: Managed to get the server booting, I had run grub-install manually:
grub-install /dev/mapper/mpatha
Hope this helps