An apparatus and method for testing a network-based storage virtualization system. A tester is connected to a host side of a storage virtualization system. The tester provides test scripts to the storage virtualization system to test I/O and other operations. A separate link, independent of said storage virtualization system, is provided to a storage side of said storage virtualization system to allow verification of the correct translation from virtual to physical independent of the data path used by the virtualization system. Thus, the tester verifies, over the separate link, the physical configuration of VLUNs and data written to the VLUNs by the tester on storage devices.