Using Leases to Support Server-Driven Consistency in Large-Scale Systems

This paper introduces volume leases as a mechanism for providing cache consistency for large-scale, geographically distributed networks. Volume leases are a variation of leases, which were originally designed for distributed file systems. Using trace-driven simulation, we compare two new algorithms against four existing cache consistency algorithms and show that our new algorithms provide strong consistency while maintaining scalability and faulttolerance. For a trace-based workload of web accesses, we find that volumes can reduce message traffic at servers by 40% compared to a standard lease algorithm, and that volumes can considerably reduce the peak load at servers when popular objects are modified.