On Consistent Checkpointing in Distributed Systems

Consistent checkpointing simpliies failure recovery and eliminates the domino eeect in case of failure by preserving a consistent global checkpoint on the stable storage. However, the approach suuers from high overhead associated with the checkpointing process. Two approaches are used to reduce the overhead: one is to minimize the number of synchronization messages and the number of checkpoints; the other is to make the checkpointing process non-blocking. These two approaches were orthogonal in previous years until the Prakash-Singhal algorithm 17] combined them. In other words, the Prakash-Singhal algorithm forces only a minimum number of processes to take checkpoints, and it does not block the underlying computation. In this paper, we identify two problems in their algorithm 17] and prove that there does not exist a non-blocking algorithm that forces only a minimum number of processes to take their checkpoints. Based on the proof, we present an eecient algorithm that neither forces all processes to take checkpoints, nor blocks the underlying computation during checkpointing. Correctness proofs are also provided.