One critical factor in powering a server farm is cooling. If heat is not removed from the

Question:

One critical factor in powering a server farm is cooling. If heat is not removed 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. 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 a Sun Niagara 8-core processor, 1 GB 240-pin DRAM, and a single 5400 rpm hard drive can you cool with one cooling door?
b. 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. In a single rack, the MTTF of each processor is 4500 hours, of the hard drive is 9 million hours, and of the power supply is 30K hours. For a rack with 8 processors, what is the MTTF for the rack?