A User-Centered Approach to Active Replica Management in Mobile Environments

A replication scheme determines the number and location of replicas in a distributed system. Traditional static replication schemes do not perform well in mobile environments due to the assumptions of fixed hosts, relatively static access patterns, and the lack of considerations on users' behalf. For effective data management in mobile environments, we define the notion of activity-data dependency for inferring the information requirement of mobile users based on their scheduled activities. We then propose a dynamic replication scheme which employs user profiles for recording users' mobility schedules, accesses behaviors and read/write patterns, and actively reconfigures the replicas to adapt to changes in user locations, data requests, and system status. Simulation results demonstrate that the scheme can accurately predict the data requirement to facilitate effective replication, reduce response time, and increase data availability.