Energy-efficient Passive Replication of a Process in Mobile Environment

Processes requested by clients are performed on servers in a cluster of servers. Here, not only QoS (quality of service) requirements like response time are satisfied but also the total electric power consumed by servers to perform processes has to be reduced. Furthermore, each process has to be reliably performed in presence of server faults. In this paper, we consider a mobile agent where a process, i.e. mobile agent, is reliably performed by moving around servers in presence of server faults. A replica of a mobile agent is first performed on one primary server while the other replicas of the agent are sent to other secondary servers. While performing the primary agent replica, the server takes checkpoints of the primary agent replica and sends the checkpoints to the secondary agent replicas. If the primary replica is faulty due to the fault of the primary server, one of the secondary replicas takes over the primary replica. The more number of agent replicas are performed, the more reliably the agent can be performed but the more amount of electric power is consumed by the servers. Hence, it is critical to discuss how to reliably and energy-efficiently perform mobile agents on multiple servers. In this paper, we discuss how to reduce the total electric power consumption in a cluster where each agent is passively replicated on multiple servers. If the primary server is faulty, one of the secondary servers gets primary. We evaluate the energy-efficient passive replication (EPR) scheme of a mobile agent in terms of total power consumption and average execution time and response time of each mobile agent in presence of server fault.