1. A computer-implemented method of performing a storage performance test to evaluate moving a logical unit of storage (LUN), the computer-implemented method comprising: while a set of host computers accesses a production LUN on a source array, adding a test LUN on a target array, the source array and the target array being different data storage arrays; after the test LUN is added on the target array, duplicating host input/output (I/O) requests from the set of host computers to form a first set of the host I/O requests for processing on the production LUN on the source array and a second set of the host I/O requests for processing simultaneously on the test LUN on the target array; and while the first set of the host I/O requests are processed on the production LUN on the source array and the second set of the host I/O requests are processed simultaneously on the test LUN on the target array, performing a set of performance evaluation operations on the target array to assess a performance outcome of moving the production LUN from the source array to the target array; wherein a data storage appliance is interconnected between the set of host computers and the source and target arrays; and wherein the computer-implemented method further comprises: presenting, by the data storage appliance, the production LUN to the set of host computers while hiding the test LUN from the set of host computers.