FAN fine control optimizes the rotation speeds of cooling fans in the storage system for power saving. This function monitors the air temperature outside the storage system (intake air temperature) and the temperatures of heat generating parts (such as, CPUs, drives, and protocol chips). Based on the monitored temperatures, this function automatically controls the rotation speeds of cooling fans so that the minimum required speeds for power and noise are attained. Thus, the power consumption is optimized. No setting is required because this function runs automatically.