Recent years have witnessed an increasing trend of distributed information systems with high-capacity communication channels. The purpose of this thesis is to describe a mathematical programming model to decide where to place data files considering computer capacities in a distributed computer network. This decision must trade off the cost of accessing a database, which is reduced by additional copies, against the cost of storing and updating the additional copies. This model makes allowance for the allocation of multiple copies of files, the determination of the optimal number of redundant copies, and the choice of the appropriate computer systems. The solution procedures based on Lagrangean approaches including a heuristic are presented. And successful computational experience is reported.