You'll need to edit the /etc/multipath.conf file to add a blacklist exception for your drives.
When you edit the /etc/multipath.conf look for the section that says "blacklist_exceptions". In there add the SCSI vendor ID and SCSI product ID for the manufacturer of your hard drives.
For example, if you have a device at /dev/sdf you can use the command "sg_inq /dev/sdf" and it will show you the vendor ID in the "Vendor identification: " section and the SCSI product ID in the "Product identification:" section.
After that run 'service multipath-tools restart', then run 'multipath -ll' to see the list of paths.
Be sure to run all of these commands without the quotes.
Once multipathing is properly configured you can then create a storage pool using the device mapper paths.
Please review the link below for additional detail: