You can set an external managed disk (MDisk) as a quorum disk by using the command-line interface (CLI).
To set an external MDisk as a quorum disk, use the chquorum command.
Quorum disk configuration describes how quorum disks are used by the system, and how they are selected. The system automatically assigns quorum disks. Do not override the quorum disk assignment if you have a system that does not have external MDisks. For system with more than one control enclosure and with external MDisks, distribute the quorum candidate disks (when possible) so that each MDisk is provided by a different storage system. For a list of storage systems that support quorum disks, search for supported hardware list at the following website:
http://support.lenovo.com/us/en/products/servers/lenovo-storage