Mehmet Savsar - Kuwait University, Kuwait
Fawaz S. Al-Anzi - Kuwait University, Kuwait

This paper presents a stochastic model to evaluate the reliability and availability of a network service configuration consisting of a centralized database server and two or more distributed database servers for a local/metropolitan area network (LAN or MAN). The centralized server monitors and controls the distributed database servers, which can be remotely separated from each other and from the center by almost any amount of distance depending on the means of information transmission media between the center and the distributed servers. Using exponential time to failure and time to repair distributions for each of the database servers, exact numerical solutions are obtained for the steady state service reliability and availability measures. The results are then compared to approximate numerical solutions for general Weibull distribution case under different initial conditions. The reliability study of such configuration has many applications in widely used internet services, mission critical business fault tolerant systems, and automated manufacturing and service industries.

Distributed Database Servers, Network Reliability, Markov Model, Server Availability