Adaptive file system consistency for unreliable mobile computing environments

This paper presents the design and implementation of the Mobile File and Adaptation System (MFAS), a system to provide efficient data access mechanisms over variable quality of service networks. MFAS supports fine-grained file caching and consistency, and provides a mechanism for mobility-aware applications to adapt the caching and consistency behavior as network conditions change. Over low-bandwidth links, MFAS shows substantial performance gains over typical network file systems by sending only the modified portions of files. To our knowledge, MFAS is the first system that efficiently supports application-directed consistency policies at the subfile level.