Algorithms for Maintaining Consistency of Cached Data for Mobile Clients in Distributed File System

Abstract

A cache stores data in order to serve future requests to those data faster. In mobile devices, the data have to be transferred from a server through the mobile network before being stored in the cache. The mobile network is prone to failure caused by users' movements and by the placement of base transceiver stations. Moreover, the mobile devices use various telecommunications technologies and therefore the speed of the network is highly variable. Using a cellular network for communication is also expensive. The cache is an intermediate component which addresses this problem. Once the data are downloaded, they can be stored in the cache for possible future reuse. When using a cache, the system designer presumes that the data will be requested again in the future. On the other hand, the original data stored on the server can be changed. Then, the cached data are in an inconsistent state. In this paper, authors present an adaptive method for maintaining the consistency of cached data which saves network traffic by reducing the number of messages needed for inconsistency detection.