Before adding a second controller to the controller shelf, you must change the configuration to duplex by installing a new NVSRAM file and using the command line interface to set the storage array to duplex.
Steps
Step 1: Install duplex NVSRAM
Change the configuration to duplex by installing a new NVSRAM file. The duplex version of the NVSRAM file is included with the download file for SANtricity OS Software (controller firmware).