A Recoverable Distributed Shared Memory Integrating Coherence and Recoverability

Large-scale distributed systems are very attractive for the execution of parallel applications requiring a huge computing power. However, their high probability of site failure is unacceptable, especially for long time running applications. In this paper, we address this problem and propose a checkpointing mechanism relying on a recoverable distributed shared memory (DSM). Although most recoverable DSM require speciic hardware to store recovery data, our scheme uses standard memories to store both current and recovery data. Moreover, the management of recovery data is merged with the management of current data by extending the DSM's coherence protocol. This approach limits the hardware development and takes advantage of the data replication provided by a DSM in order to limit the amount of transferred pages during the checkpointing. The paper also presents an implementation and preliminary performances evaluation of our recoverable DSM on an Intel Paragon with 56 nodes. In particular, it shows performance degradation introduced by the fault tolerance mechanisms on failure-free executions, compared to a standard DSM on the same architecture. A Recoverable Distributed Shared Memory Integrating Coherence and Recoverability 3 1 Introduction