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Efficient and Effective File Replication and Consistency Maintenance in P2P Systems

Speaker  Haiying (Helen) Shen

Affiliation  Clemson University

Host  Jin Li

Duration  01:08:05

Date recorded  11 September 2009

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without considering file replication dynamism, leading to inefficient file update and hence high possibility of outdated file response.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.

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