Consider the system in Figure 7.6. Suppose that server 2 is replaced by one exactly twice as fast.

Does this replacement result in significant improvement in the mean response time of the network? Explain via operational laws.

Explain your answer to (a) by showing a time-line of where the jobs are at each step, both before and after the replacement. To do this you will need to make the problem deterministic, so you should assume that the service time at each server is a constant and that jobs alternately go to server 1 and 2. This is not meant to be a proof, just an explanation of what is going on, Make sure that you extend your time-line long enough that the average response time becomes clear.

Given that the replacement has been made, is there any further modification you would propose to improve the mean response time in the closed system that does not involve spending more money? By how much would your modification improve performance?

N=6 Server 1 Server 2 Figure 7.6. The system prior to improvement. N=6 Server 1 Server 2 Figure 7.6. The system prior to improvement