Disclosed is a method and mechanism for virtualizing the resources of multiple physical storage controller cards/HBAs available to a host computer system into a single virtual controller. An Advanced Storage Driver (ASD) may be inserted in a layer above the base device drivers of the storage controllers/HBAs and act as a single virtual controller for access to the end target devices connected to the multiple physical storage controllers/HBAs so that at any point in time the resources of each of the controllers/HBAs may be dynamically allocated to the various requested operations. The ASD may have bi-directional communication with each controller/HBA firmware directly and/or with the base device driver associated with each controller/HBA in order to permit both direct and base device driver controlled communication with each of the physical controllers/HBAs. The ASD may further provide load sharing between the controllers/HBAs as well as fault tolerance functionality to reroute communications through a different controller/HBA in the event of a failure of one or more of the controllers/HBAs.