The invention relates to a redundancy storage virtualized subsystem for providing data storage space, which comprises a pair of redundancy external storage virtualized controllers and at least one entity storage device in each group; wherein the redundancy external storage virtualized controllers comprises a first storage virtualized controller and a second storage virtualized controller for coupling to a host unit; the at least one entity storage device is connected to a serial attached small-scale computer system interface input and output device link controller of the pair of storage virtualized controllers respectively through two ports. When one of the storage virtualized controllers of the pair of redundancy external storage virtualized controllers is not online or is offline after being online, the other storage virtualized controllers of the pair of redundancy external storage virtualized controllers can automatically take over the functions executed by the original storage virtualized controller of the pair of redundancy external storage virtualized controllers.