A storage system is configured to create and manage virtual ports on physical ports. The storage system can transfer associations between virtual ports and physical ports when a failure occurs in a physical port or a link connected to the physical port so that a host can access volumes under the virtual ports through another physical port. The storage system can also change associations between virtual ports and physical ports by taking into account the relative loads on the physical ports. When a virtual machine is migrated from one host computer to another, the loads on the physical ports in the storage system can be used to determine whether load balancing should take place. Additionally, the storage system can transfer virtual ports to a remote storage system that will take over the virtual ports, so that a virtual machine can be migrated to remote location.