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M i n i m i z i n g P o w e r U s a g e i n i m i z i n g P o w e r U s a g e

Use Large Buffers
If your organization is one where media is played from a CD, DVD, or hard drive, make
sure that applications’ buffers are set large enough to store as much of the media in memory
as possible. Doing this reduces the hard drive, DVD, or CD drive from spinning as much
and thus saves power.

Storage
Storage is another big area in the realm of power consumption. Although you want to have
a measure of redundancy protecting your data, it’s simply wasteful and inefficient to have
hundreds of drives spinning away when a couple dozen will do the trick.
Chances are your organization’s storage started in one, logical way, but has since
become something else. Just by adding to what you have, the reasonable system you had in PART II
place a few years ago has become Frankenstorage. Now’s a good time to reevaluate your
storage and see where you can make logical changes.

Green Drives
Green hard drives are drives that reduce the amount of power they use through a variety of
mechanisms, including unloading the heads during idle time to reduce aerodynamic drag.
Further, the drives calculate the optimum seek speed to use just the amount of power
necessary.
Western Digital is a major producer of green hard drives and estimates that its green
drives can shave off US$10 per drive, per year in electricity costs. For example, its 1TB WD
Caviar GreenPower hard drive uses about 5 watts less power than drives of the same size,
which typically consume 13.5 watts.

NOTE Western Digital is used here as an example. It is certainly not the only company to produce
green drives. Hitachi and Samsung also offer such drives, and the market is only going to open
up with more vendors, greater capacities, and speedier seek times.You can compute the math out
even further on this. A datacenter with 10,000 drives can save US$100,000 in annual costs.
Plus, carbon dioxide emissions are cut by 600 metric tons. That’s the equivalent of taking
400 cars off the road for one year.

NOTE Solid state drives (SSDs) have no moving parts and use much less energy. Although that fact
alone is notable, it is also worth noting that they are very expensive and don’t yet hold a great
capacity. For the price of one SSD you could buy more than 50 traditional hard drives. We
mention it here for the sake of completeness, but it is a very costly option and not as efficient.

MAID
A massive array of idle disks (MAID) is a system that employs hundreds or thousands of
hard drives for near-line data storage.

NOTE The term near-line is used to define the area between online and offline storage.

MAID is designed for write once, read occasionally (WORO) applications. In this model,
drives are spun up only on demand to access data stored on them. Because only a small
amount of the data is being accessed, these disks can be powered as needed, thus reducing