Windows Server 2008 Greener Than Past Releases, Microsoft Says

Published: June 18, 2008

by Alex Woodie

Want to go green? If cutting power costs or curbing greenhouse emissions are important to you, you should be running Windows Server 2008, according to Microsoft. The new operating system brings new power management features that boost its efficiency by up to 10 percent compared to Windows Server 2003, allowing Microsoft to promote Windows Server 2008 as a green, energy-efficient product suited for organizations with goals of energy consumption.

Microsoft tested the two server operating systems and published the results in a recently released white paper titled "Windows Server 2008 Power Savings." In the white paper, which can be downloaded in Word format here, Microsoft loaded the operating systems onto a single server equipped with two dual-core 64-bit processors and 4 GB of RAM. Microsoft did minimal configuration of the operating systems, and then took the server through a series of load tests.

The tests show that an out-of-the-box (or OOB) configuration of Windows Server 2008 consumed 10 percent less electricity than Windows Server 2003 to accomplish the same piece of work (as measured by file throughput and wattage). What's more, when running full-tilt boogey, the OOB Windows Server 2003 box could only do 80 percent of the work of the Windows Server 2008 OOB. This test didn't include any external disk drives.

Microsoft attributed the bulk of those savings to new processor power management (PPM) features in Windows Server 2008. PPM enables the operating system to throttle the amount of voltage sent to the processor, based on load, which is measured 10 times per second, according to Microsoft. PPM is enabled by default on Windows Server 2008. Power states, or P states, can also be configured in Windows Server 2003, but it runs in full-power mode by default.

Those PPM capabilities were tested again, this time on an enterprise-class Web server with four quad-core processors, 16 gigabytes of RAM, and a 288 GB external disk array. (Again, the same physical server was used for both tests.) Microsoft measured the Web server's energy consumption when running at idle and when serving data to 20 clients, and found the Windows Server 2008 box consumed 2.3 percent less energy than the Windows Server 2003 box at idle, and 6.8 percent less while serving requests.

In terms of annual energy consumption, the Windows Server 2008 box would cost $20 less per year at idle, and about $30 less per year when running at a slow jog. In terms of greenhouse gas emissions, the newer box generated 70 kilograms less carbon dioxide at idle, and 250 kilograms of carbon dioxide less when serving 20 clients. Those numbers start to add up as the Windows server farm grows.

The energy savings become even more pronounced when Hyper-V, Microsoft's upcoming new virtualization product, is put into production. Microsoft took the four-way server it used for the Web serving test and used Hyper-V to carve four virtual machines out of Windows Server 2008. (Because Windows Server 2003 isn't compatible with Hyper-V, the tests measured energy consumption between virtualized and non-virtualized versions of Windows Server 2008.)

Microsoft found it took about 4 percent more energy to run the Windows Server 2008 server carved into four virtual machines compared to the server running just one copy of Windows Server 2008. This led Microsoft to say that "you can add virtual machines at essentially no power cost, as dictated by your hardware and performance needs."

Unfortunately, this is where the data starts to break down for Microsoft. The company also tested the same server carved by Hyper-V into 10 virtual machines running the Web server, and reports that this machine consumed only 2.4 percent more energy than the stand-alone machine. According to this data, it takes more energy to run a server with four Windows OS images on it than one with 10 Windows OS images. That doesn't seem right, and is probably why Microsoft chose to highlight the test results of the machine with four virtual machines.

Microsoft is correct in its conclusion that Hyper-V stands to provide big energy-saving benefits to Windows Server 2008 customers, although they might not be to the same extent as Microsoft is claiming. The truth is customers can get similar benefits running any type of virtualization software on their Windows servers. Users must keep in mind some of the other costs that virtualization entails, and make sure they don't cancel out the efficiency gains of virtualization.

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