FRASystem: fault tolerant system using agents in distributed computing systems

In this paper, we present a fault tolerant and recovery system called FRASystem (Fault Tolerant & Recovery Agent System) using multi-agent in distributed computing systems. Previous rollback-recovery protocols were dependent on an inherent communication and an underlying operating system, which caused a decline of computing performance. We propose a rollback-recovery protocol that works independently on an operating system and leads to an increasing portability and extensibility. We define four types of agents: (1) a recovery agent performs a rollback-recovery protocol after a failure, (2) an information agent constructs domain knowledge as a rule of fault tolerance and information during a failure-free operation, (3) a facilitator agent controls the communication between agents, (4) a garbage collection agent performs garbage collection of the useless fault tolerance information. Since agent failures may lead to inconsistent states of a system and a domino effect, we propose an agent recovery algorithm. A garbage collection protocol addresses the performance degradation caused by the increment of saved fault tolerance information in a stable storage. We implemented a prototype of FRASystem using Java and CORBA and experimented the proposed rollback-recovery protocol. The simulations results indicate that the performance of our protocol is better than previous rollback-recovery protocols which use independent checkpointing and pessimistic message logging without using agents. Our contributions are as follows: (1) this is the first rollback-recovery protocol using agents, (2) FRASystem is not dependent on an operating system, and (3) FRASystem provides a portability and extensibility.