Evaluation of Replica Placement Strategies for a Shared Data Space in Mobile Ad-Hoc Networks

The dynamic nature of mobile ad-hoc networks (MANETs) can easily lead to data being inaccessible due to constant route changes and network partitions. One method often used for increasing reliability and availability of data is replication. However, replication comes with costs, those of transferring and storing data and keeping track of consistency between replicas. For that reason, we have identified the core factors impacting the resulting network traffic. We have performed experimental studies with a real world prototype of a distributed data management system for MANETs. Further-more, we have done an extensive simulation study showing where table replicas should be placed in the network, in order to minimize network traffic generated by access to the data-bases and by the synchronization data. The results of the experiments are consistent and show that by using clustering techniques we can achieve close-to-optimal traffic by placing replicas on approximately 10 % of nodes.