When deploying a Microsoft cluster with shared disk resources on a san, be sure that the SAN controller supports “capacity extension” technology.  If this is not supported, it will be impossible to add storage capacity to the existing disk resource.  A new resource will have to be created. [more]

Even after capacity is extended on the shared disk resource,  Windows will not recognize it, because shared disk resources are basic disks, and cannot be converted to dynamic.  The extra capacity can be utilized only by extending the partition using the diskpart command(use caution!).