Figure 1.23 presents the power consumption of several computer 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)?