The electric power consumption of information systems has to be reduced in addition to increasing the performance and fault-tolerancy in order to realize green societies. In information systems, servers mainly consume the electric power to perform processes requested by clients. We consider computation (CP) and storage (ST) types of application processes on servers. In CP and ST processes, CPU and storage drives are mainly consumed, respectively. First, we present the storage-based power consumption (SBPC) model of a server st to perform ST and CP processes. The SBPC model is a four state model, where the power consumption rate of a server is one of four rates minEt, STt, Ct, and STCt. Here, the power consumption rate Et( t) of a server st at time is minimum minEt if no process is performed. The power consumption rate Et(t) is STt if only and at least one ST process is performed Et(t) in a server st. Et(t) is Ct if only and at least one CP process is performed on the server st. If both ST and CP processes ar concurrently performed, Et(t) is STCt. Here, minEt