CMV: File consistency maintenance through virtual servers in peer-to-peer systems

摘要

Peer-to-peer (P2P) has become a mainstream architecture in numerous diverse distributed applications. However current P2P systems do not provide consistency guarantees under multiple reader multiple writer scenarios. Such a feature is desirable as well as necessary for supporting more diverse applications than merely file-sharing systems. In this paper, we develop a highly scalable and efficient algorithm, called Consistency Maintenance through Virtual servers (CMV), in P2P systems. In this algorithm, consistency of each dynamic file is maintained by a Virtual Server (VS). A file update can only be accepted through the VS to ensure one-copy serializability consistency. The VS of a file is a logical network composed of multiple Replica Peers (RPs) that have replicas of the file. Mathematical analysis is performed for optimal parameter selections that achieve minimum overhead messages for maintaining file consistency. Simulation experiments are conducted to compare the performance of the proposed CMV algorithm with two existing schemes, namely the rumor spreading based scheme and the Update Propagation Through Replica Chain (UPTReC) scheme. Our results show that CMV can quickly commit update to the system and significantly reduce (by more than 90%) overhead messages compared to these schemes under various system conditions.