SearchServerVirtualization published a good article about a never exposed benefit of virtualization: power saving and environmental impact reduction.
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The amount of electricity used, of course, depends upon the server. An efficient low-end server might use as little as 200 watts an hour, while a newer, more powerful server can consume 450 watts. Older servers can use well over 500 watts. In order to calculate the cost of running a server, we need to know the cost per kilowatt hour (KWH). Pacific Gas and Electric says that a good average for businesses in northern California is 15 to 17 cents, and rising. Because servers usually run 24 hours a day, seven days per week, that means the total electric cost per month (at 15 cents per KWH) to operate just one low-end server comes to $22; a newer server costs $38 and an inefficient server costs more than $50.
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Consider, for example, a data center populated with a mix of old and new servers of varying configurations with an estimated average total energy cost per month of $75 each. If the organization consolidates 100 physical servers onto six new two-CPU dual core servers, the net electric/power savings for the 94 virtualized servers comes to approximately $423,000 over five years. If the organization pays $6,000 for each physical server (including tax, shipping and set-up) and commonly refreshes servers once every five years, then additional savings of approximately $560,000 are realized over a five-year period for 94 servers that don’t need to be replaced. This is a combined savings over five years of almost $1 million.There are additional long-term cost reductions with virtualization. New applications will reside on cost-effective virtual servers instead of new physical servers. This results in lower electric/power requirements and a reduction in network cards, network switches, SAN HBAs and maintenance contracts — not to mention a potential reduction in data center components such as air conditioners, PDUs and UPS devices. Because virtual machines require only about 33% of administrative time as their physical servers, there is a further significant reduction in the IT staff time required to support them….
Read the whole article at source.