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Consolidation
The first place to start with any datacenter greening project is to consolidate servers. In
some cases, you might find servers that you don’t even need and you can just turn them off.
Between 10 and 30 percent of servers aren’t even being used and could be deactivated.

NOTE If you take one physical server out of service, you’ll save about US$560 in yearly electrical
costs (that’s assuming 8 cents per kWh).

As soon as unused servers have been taken out, the next step is to consider consolidation.
Many servers are underused, in terms of their processing power, as Figure 11-4 shows. Most
physical servers run at a maximum of 15 percent.
Move as many server-based applications as you can to a virtual machine. A virtual
machine is simply a software server installed on a physical server. You can put a number of
virtual machines onto a physical server. This will result in a sharp drop in the number of
physical servers in your datacenter. The servers that take on the additional roles will be
more efficient in terms of their utilization levels.

Total utilization:
Total utilization: 20 percent
20 percent File servers

Total utilization:
80 percent

The duties of
these servers
can be PART V
combined on
Total utilization: this machine, Total utilization:
20 percent improving 20 percent
utilization.

Web server E-mail server
FIGURE 11-4 By consolidating servers, you reduce the amount of servers you’re paying to power, plus
you are increasing the utilization of the tasked machines.