Wireless networks present unusual challenges for mobile file system clients, since they are characterised by unpredictable connectivity and widely-varying bandwidth. The traditional approach to adapting network communication to these conditions is to write back file updates asynchronously when bandwidth is low. Unfortunately, this can lead to underutilisation of bandwidth and inconsistencies between clients. We describe a new mobile file system, MAFS, that supports graceful degradation of file system performance as bandwidth is reduced, as well as rapid propagation of essential file updates. MAFS is able to achieve 10-20% improvements in execution time for real-life file system traces featuring read-write contention.
Benjamin Atkin, Kenneth P. Birman