A New Checkpointing Approach for Mobile Distributed System

In this paper, we introduce a weighted checkpointing approach for the mobile distributed computing system (MDCS) that significantly reduces checkpointing overheads on mobile nodes. Checkpoint protocols proposed so far in the literature for MDCS are either coordinated, log based or quasi-synchronous. Coordinated checkpointing requires extra synchronization messages and may block the underlying computation. In quasi-synchronous approach processes have limited autonomy in checkpointing and all nodes need not to checkpoint concurrently as in the case of coordinated checkpointing. Also, only limited messages are logged as compared to log-based checkpointing where all messages are logged. Quasi-synchronous checkpointing protocols guarantee a consistent global state but the checkpointing frequency is governed by the message arrival pattern at various nodes and thus results in dynamic checkpointing overhead that cannot be anticipated. As a remedy for this, we propose a protocol that uses a hybrid of quasi-synchronous and message-logging approaches combined with the concept of weighted checkpoints. The weighted quasi-synchronous approach proposed by us requires no synchronization messages, reduces the checkpoints taken by the mobile nodes but requires logging of messages for mobile nodes. Simulation results and Comparison shows that the new approach is better than other proposed approaches.