A redundant controller storage virtualization subsystem performing host-side IO rerouting and dynamic logical media unit reassignment. In one embodiment, the assignment of logical media unit owner can be dynamically reassigned to the receiving storage virtualization controller which was originally not the logical media unit owner such that the receiving storage virtualization controller becomes new logical media unit owner to execute the IO request. In another embodiment, the dynamic logical media unit reassignment can be performed according to the operating condition(s) of the storage virtualization system so as to improve the performance of the storage virtualization system. In a further embodiment, the controller storage virtualization subsystem can perform host-side IO rerouting when the timing for performing dynamic logical media unit reassignment is not reached.