A fast algorithm for reliability-oriented task assignment in a distributed system

Distributed systems (DS) have become a major trend in computer systems design today because of their high speed and high reliability. Reliability is an important performance parameter in DS design. The distribution of programs and data files can affect the system reliability. Usually, designers add redundant copies of software and/or hardware to increase the system's reliability. The reliability-oriented task assignment problem, which is NP-hard, is to find a task distribution such that the program reliability or system reliability is maximized. In this paper, we developed a reliability-oriented task allocation scheme, based on a heuristic algorithm, for DS to find an approximate solution. The simulation shows that, in most test cases with one copy, the algorithm finds suboptimal solutions efficiently. When the algorithm cannot obtain an optimal solution, the deviation is very small; therefore, this is a desirable approach for solving these problems.