Figure 1.23 presents the power consumption of several com- puter system components. In this

Figure 1.23 presents the power consumption of several com- puter system components. In this exercise, we will explore how the hard drive affects power consumption for the system.

a. Assuming the maximum load for each component, and a power supply efficiency of 70%, what wattage must the server’s power supply deliver to a system with a Sun Niagara 8-core chip, 2 GB 184-pin Kingston DRAM, and two 7200 rpm hard drives?

b. How much power will the 7200 rpm disk drive consume if it is idle rougly 40% of the time?

c. Assume that rpm is the only factor in how long a disk is not idle (which is an oversimplification of disk performance). In other words, assume that for the same set of requests, a 5400 rpm disk will require twice as much time to read data as a 10,800 rpm disk. What percentage of the time would the

5400 rpm disk drive be idle to perform the same transactions as in part (b)?