Customers tell us that energy-efficient computing is a top priority for them as they look to control energy costs and reduce their impact on the environment. With Windows Server 2008 we feel we have some very compelling technologies such as Server Virtualization with Hyper-V and the native Power Management capabilities of the platform, that are on by default, which will allow organizations to realize true power savings benefits.

We have been working across multiple teams at Microsoft since last October, and are pleased to release today; a new whitepaper (download link) that outlines the key power savings benefits of Windows Server 2008, which has been designed with energy efficiency in mind.  In this whitepaper we explore how Windows Server 2008 provides customers with a number of new power-saving features including:

· Support for Processor Performance States (P-states): Windows Server 2008 has the native ability, turned on by default, to throttle the amount of voltage to the CPU based on load. Ten times every second, Windows Server 2008 is evaluating the workload on the processor and adjusts the P-States accordingly.  Our testing has shown up to a 10% power savings increase from Windows Server 2003 to Windows Server 2008 while maintaining a comparable level of throughput (performance).


· Server Virtualization with Hyper-V: The implications of these results are significant: if multiple virtual machines can run on a single physical machine without consuming significantly more power than a standalone server while keeping comparable throughput, that means you can add virtual machines at essentially no power cost, as dictated by your hardware and performance needs. The savings continue to scale with the number of servers you are able to virtualize. Running 4 virtual machines means saving the equivalent power output of three physical servers; running 10 virtual machines means saving the equivalent power output of 9 physical servers. Plus, Hyper-V can still throttle the amount of voltage to the CPU based on load – which is something VMware and Xen can NOT do today.


· Support for Advanced Configuration and Power Interface (ACPI) processor power management (PPM): We can fine-tune the power profiles of both Windows Server and Windows Vista through Group Policy allowing organizations to tailor the Power Profile of their systems.  How do you tailor the power settings within Windows Server for the best Power/Performance settings in mind?  The default settings are great in most situations, but you can check out the Windows Server Tuning Guides that have recently been updated for Power Management and Hyper-V settings.


In all, the whitepaper shows us that the inherent power management and virtualization capabilities of Windows Server 2008 can lead to cost and energy savings across the board.

Supporting the whitepaper, which is in .docx or .pdf format, we have 3 appendixes that contain the raw power management data derived from the tests: (Download Link)

  • Windows_Server_2008_Power_Savings.docx
  • Windows_Server_2008_Power_Savings.pdf
  • Appendix_A_-_Test_Results_Spreadsheet.xlsx
  • Appendix_B_-_System_Information_and_Test_Tools.docx
  • Appendix_C_-_Throughput.xlsx

With Windows Server 2008 we have come a long way with our Power Management capabilities....especially when contrasted to Windows 2000 and Windows Server 2003.  As we look to future versions of the Server OS, Power Management will be a core tenet of our development efforts.

Ward Ralston & Eric Rezabek