Adaptive Replica Synchronization for Distributed File Systems

This paper presents an adaptive replica synchronization mechanism among storage servers (SSs) without the interference from the metadata server (MDS) in a distributed file system. This mechanism employs a chunk list data structure, which holds the information about the relevant chunk replicas and is stored on the associated SSs corresponding to the replicas. Combined with version-based update replay technique, our proposed mechanism can ensure data consistency from the viewpoint of clients and help the SSs to conduct replica synchronization proactively with a per-chunk granularity. In contrast to conventional approaches of replica synchronization that are reliant on the MDS to trigger the synchronization, our proposed mechanism can side step the cumbersome centralized synchronization process to accomplish the same synchronization job. Moreover, a deferred update approach for replica synchronization has been adopted by the newly proposed mechanism for contributing to I/O data rate in write-intensive workloads. The evaluation experiments show that this newly presented mechanism can achieve attractive I/O performance enhancement with less synchronization overhead in specific application contexts.