A unified storage system for executing a variety of types of storage control software using a single standardized hardware platform includes multiple storage control modules connected to storage devices for storing data related to input/output (I/O) operations. A first type of storage control software is initially installed and executed on a first storage control module for processing a first type of I/O operations. A management module replaces the first type of storage control software by installing a second type of storage control software onto the first storage control module. When the second type of storage control software is installed and executed, the first storage control module processes a second type of I/O operation, different from the first type of I/O operation. Control of volumes originally accessed by the first storage control module may be transferred to a second storage control module having the first type of storage control software installed.