Fundamentals of Quantitative Design and Analysis - Computer Architecture: A Quantitative Approach - page 65

1.4 [20/10/20] <1.5> Figure 1.23 presents the power consumption of several computer system
components. In this exercise, we will explore how the hard drive affects power consump-
tion for the system.
a. [20] <1.5> Assuming the maximum load for each component, and a power supply ei-
ciency of 80%, what watage must the server's power supply deliver to a system with
an Intel Pentium 4 chip, 2 GB 240-pin Kingston DRAM, and one 7200 rpm hard drive?
b. [10] <1.5> How much power will the 7200 rpm disk drive consume if it is idle roughly
60% of the time?
c. [20] <1.5> Given that the time to read data of a 7200 rpm disk drive will be roughly
75% of a 5400 rpm disk, at what idle time of the 7200 rpm disk will the power con-
sumption be equal, on average, for the two disks?
FIGURE 1.23 Power consumption of several computer components .
1.5 [10/10/20] <1.5> One critical factor in powering a server farm is cooling. If heat is not re-
moved from the computer efficiently, the fans will blow hot air back onto the computer,
not cold air. We will look at how different design decisions affect the necessary cooling,
and thus the price, of a system. Use Figure 1.23 for your power calculations.
a. [10] <1.5> A cooling door for a rack costs $4000 and dissipates 14 KW (into the room;
additional cost is required to get it out of the room). How many servers with an Intel
Pentium 4 processor, 1 GB 240-pin DRAM, and a single 7200 rpm hard drive can you
cool with one cooling door?
b. [10] <1.5> You are considering providing fault tolerance for your hard drive. RAID 1
doubles the number of disks (see Chapter 6 ) . Now how many systems can you place
on a single rack with a single cooler?
c. [20] <1.5> Typical server farms can dissipate a maximum of 200 W per square foot.
Given that a server rack requires 11 square feet (including front and back clearance),
how many servers from part (a) can be placed on a single rack, and how many cooling
doors are required?
1.6 [Discussion] <1.8> Figure 1.24 gives a comparison of power and performance for several
benchmarks comparing two servers: Sun Fire T2000 (which uses Niagara) and IBM x346
(using Intel Xeon processors). This information was reported on a Sun Web site. There are
two pieces of information reported: power and speed on two benchmarks. For the results