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The Greening of IT
234 How Companies Can Make a Difference for the Environment

center and the heat they generate. Sun has invested in smart-cooling tech-
nology to reduce the considerable energy that typically goes to cool hot-
running servers. For instance, in one data center room on the Santa Clara
campus, servers are arrayed in long black pods called hot aisles. Hot air
from the machines blows into the interior of the closed pod where it is
captured by heat exchangers.
Sun is continuing to explore other ways to further green its data cen-
ters. For instance, the polluting diesel backup generators that most data
centers rely on might be replaced by fuel cells—or converted to run on
biodiesel.

Chip Technology and Green IT

More-efficient processors can be a significant energy-saving element,
as IBM, Intel, Advanced Micro Devices, and Sun Microsystems all have
green chips. Where chip makers used to compete entirely on speed, now
they also compete on performance per watt. Microprocessors often have
built-in energy-efficiency features, such as the ability to reduce power to ptg
idle cores, sleep mode to power off inactive cores and restore power when
needed, and thermal tuning. Almost all modern microprocessors are
being designed with “hooks” for virtualization built in.

Energy Efficiency for Computer Networks

Servers and cooling equipment consume the largest fraction of data
center power by far. Little attention is given to network components,
but they also consume power and produce heat. Here’s information on
saving energy on your networks from a 2008 article by David B. Jacobs
of The Jacobs Group (http://users.rcn.com/djacobs/). Network integra-
tors can provide a valuable service by analyzing and offering ways to
lower network energy consumption, whereas resellers can replace old
network hardware with new, more energy-efficient components. Use
these energy-saving tips as a starting point. Each network is different, so
not all will apply.

■ Shut off unneeded equipment. If server virtualization has resulted
in fewer physical servers, the switch ports that supported the now-
removed servers are no longer needed. Staff reductions might have
resulted in fewer workstations and, therefore, fewer switch ports are