Embodiments of the invention relate to configuring a virtualization controller in SAN data storage system without disrupting I/O operations. One aspect of the invention concerns a method that comprises establishing a first data path between a host and a storage controller in the same communication zone wherein the storage controller comprises storage devices for storing data; adding a virtualization controller to the zone wherein the virtualization controller maps the storage devices to virtual volumes and establishes a second data path between the host and the storage devices through the virtual volumes; removing the first data path in response to the host detecting the second data path; and performing I/O operations between the host and the storage devices through the second data path.