Efficient and Effective File Replication and Consistency Maintenance in P2P Systems

In peer-to-peer file sharing systems, file replication and consistency maintenance are widely used techniques for high system performance. Despite significant interdependencies between them, these two
issues are typically addressed separately. Most file replication methods rigidly specify replica nodes, leading to low replica utilization, unnecessary replicas and hence extra consistency maintenance
overhead. Most consistency maintenance methods propagate update messages based on message spreading or a structure without considering file replication dynamism, leading to inefficient file update
and hence high possibility of outdated file response. This work proposes an Integrated file Replication and consistency Maintenance mechanism (IRM) that integrates the two techniques in a systematic and
harmonized manner. It achieves high efficiency in file replication and consistency maintenance at a significantly low cost. Instead of passively accepting replicas and updates, each node determines file
replication and update polling by dynamically adapting to time-varying file querying and update rates, which avoids unnecessary file replications and updates. To further enhance the efficiency of consistency
maintenance, this work proposes a geographically-aware Wave method (GeWave). Depending on adaptive polling in a dynamic structure, GeWave conducts update propagation between geographically close
nodes in a distributed manner, and ensures the consistency of querying results even in churn. Simulation results demonstrate the efficiency and effectiveness of IRM and GeWave in comparison with other
representative schemes. It dramatically reduces the overhead and yields significant improvements on efficiency and effectiveness of both file replication and consistency maintenance approaches.