Hardware Reference
In-Depth Information
FIGURE 6.14
Monthly OPEX for
Figure 6.13
, rounded to the nearest $5000
. Note that the
3-year amortization for servers means you need to purchase new servers every 3 years,
whereas the facility is amortized for 10 years. Hence, the amortized capital costs for servers
are about 3 times more than for the facility. People costs include 3 security guard positions
continuously for 24 hours a day, 365 days a year, at $20 per hour per person, and 1 facilities
person for 24 hours a day, 365 days a year, at $30 per hour. Benefits are 30% of salaries.
This calculation doesn't include the cost of network bandwidth to the Internet, as it varies by
application, nor vendor maintenance fees, as that varies by equipment and by negotiations.
This figure allows us to calculate a handy guideline to keep in mind when making decisions
about which components to use when being concerned about energy. The fully burdened cost
of a wat per year in a WSC, including the cost of amortizing the power and cooling infrastruc-
ture, is
The cost is roughly $2 per wat-year. Thus, to reduce costs by saving energy you shouldn't
spend more than $2 per wat-year (see
Section 6.8
)
.
Note that more than a third of OPEX is related to power, with that category trending up
while server costs are trending down over time. The networking equipment is significant at
8% of total OPEX and 19% of the server CAPEX, and networking equipment is not trending
down as quickly as servers are. This difference is especially true for the switches in the net-
working hierarchy above the rack, which represent most of the networking costs (see
Section
OPEX in
Figure 6.14
by the number of servers and hours per month, the cost is about $0.11 per
server per hour.
Example
The cost of electricity varies by region in the United States from $0.03 to $0.15
per kilowat-hour. What is the impact on hourly server costs of these two ex-
treme rates?
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