Using Location Dependence to Manage Mobile Data

Fragmentation, (portions of data located on many separate devices), and versioning, (different versions of the same datum located on different devices), of user data are increasingly prevalent and important problems as users work on a more diverse array of mobile computing devices. A common solution to these problems is to cache data on the current device. This paper describes and evaluates a mechanism for addressing fragmentation and versioning using affinity relationships. Affinity relationships that represent the current data interests of users provide hints as to what data to cache on mobile computing devices. Trace data collected over a 15 month period has been used to inform the design of the affinity mechanism. Trace-based simulation demonstrates the effectiveness of an affinity-directed approach to reduce fragmentation and versioning with low overhead.