Performance evaluation of a hierarchical replication protocol: synchronous versus asynchronous

This paper evaluates the performance of HARP, a hierarchical replication protocol based on nodes organized into a logical hierarchy. The scheme is based an communication with nearby replicas and scales well for thousands of replicas. It proposes a new service interface that provides different levels of asynchrony, allowing strong consistency and weak consistency to be integrated into the same framework. Further it provides the ability to offer different levels of staleness, by querying from different levels of the hierarchy. We present results from a detailed simulation analysis evaluating the benefits and losses in performance resulting from using synchronous versus asynchronous operations within HARP as well as comparing it with a traditional replication protocol