On Failure Recoverability of Client-Server Applications in Mobile Wireless Environments

Analytical results for the Cdf of the failure recovery time for client-server applications in mobile wireless environments characterized by logging, and mobility handoff strategies for facilitating failure recovery are reported in the paper. The results can be applied to determine if a mobile application can satisfy its recoverability requirement upon a mobile host failure when operating under a set of parameter values characterizing the mobile application, the underlying client-server environment, and the logging & mobility handoff strategies adopted by the mobile application. Model parameters which affect the shape of the failure recovery time Cdf for two mobility handoff strategies, namely, Eager and Lazy, are identified, and their effects are analyzed, with numerical data and result interpretations given. A tradeoff analysis between the cost invested by these two mobility handoff strategies for maintaining the logging and checkpoint information before failure versus the return of investment in terms of improved failure recoverability is given, and the best checkpoint interval period that would yield the best return of investment for the eager mobility handoff strategy over the lazy strategy is identified.