Sensitivity analysis of file allocation for distributed information networks

In distributed network systems, one of the most important problems is how to assign the files to servers in view of cost and delay. It is obvious that there is a trade-off relationship between costs and delays in these systems. In order to evaluate the optimal file allocation such that the total cost is minimized subject to the total delay, we have presented a system model that can cover a wide range of multimedia network applications like VoD (video on demand), corporation information networks, and so on. We have solved the optimization problem as 0-1 integer programming, have found the optimal file allocation, and have investigated the general characteristics in distributed systems. In this model, we have introduced many cost and delay parameters to evaluate the total cost and delay in the system more exactly. In constructing practical systems, it is necessary to investigate the weight and the contribution of each parameter to the total cost. It is very useful to show how to estimate cost and delay parameters on the basis of this analysis. In this paper, we analyze the sensitivity of these parameters and make clear the influence between principal parameters.