PhysicalDisks's type is []string unsupport device hints for software raid.

Here is the description from docs.openstack.org:

physical_disks - A list of physical disks to use as read by the RAID interface.
For software RAID physical_disks is a list of device hints in the same format as used for Specifying the disk for deployment (root device hints). The number of provided hints must match the expected number of backing devices (repeat the same hint if necessary).