Innovating to Improve the Planet

This increase has come over a period during which the cost of electricity itself has risen significantly. The U.S. Department of Energy reports that the average cost of electricity to the industrial sector has increased by more than 41 percent over the past seven years (2000 to 2007)—double the rate of inflation—and 33 percent for the commercial sector. Electricity costs in many other parts of the world have increased by as much or more. By taking all of these factors into account leads to the conclusion that the electricity cost of running servers is an increasingly significant expenditure for many businesses and other organizations, and will continue to grow in the future.

Aside from the direct cost of electricity, the environmental impact of excessive power usage is a growing concern for governments, businesses, and organizations seeking to reduce the production of greenhouse gases that contribute to global warming. Under international agreements such as the Kyoto Protocol and the Bali Roadmap, as well as local regulations in jurisdictions around the world, businesses and other organizations (collectively referred to as “operators”) are subject to limits on greenhouse gas emissions, which are typically managed through carbon credit programs. Operators that cut their emissions production can trade unused carbon credits on exchanges such as the European Climate Exchange, providing additional revenue. Implementing “green” policies can also provide businesses with valuable public-relations benefits among an increasingly environmentally conscious populace.

These power savings can be attributed in part to the improved support for PPM in Windows Server 2008 R2. PPM is now enabled by default, making the power savings immediately available, without additional configuration, when Windows Server 2008 R2 is installed on capable hardware. Using Group Policy, you can easily customize the PPM settings on individual servers and groups of servers across your organization as appropriate for each server’s functions and needs.

In a separate set of tests, an enterprise-class server with four quad-core processors, 16 gigabytes of RAM, and a 288GB RAID5 hard disk array was configured with Windows Server 2003 running Internet Information Services 6 (IIS6). Power consumption was monitored while the server was in an idle state, and while it was being subjected to a processing load generated by 20 active clients. Windows Server 2003 was then replaced with Windows Server 2008 R2 running Internet Information Services 7 (IIS7) on the same physical hardware, and the tests were repeated.

These tests showed Windows Server 2008 R2 using less power than Windows Server 2003 when running on the same hardware at comparable levels of throughput. Savings ranged between 2.3 percent at idle and 6.8 percent when the servers were actively servicing requests. Again, the power management configuration in both operating systems was the default OOB setting. In its default configuration, Windows Server 2008 R2 adjusts the processor performance state of capable CPUs based on workload requirements, whereas in Windows Server 2003 the CPU always runs at P0 (the highest-performance processor state) by default.

With the proliferation of physical computers in data centers, power consumption is of paramount importance. In addition to the cost-saving associated with reducing power consumption, many data centers are constrained by the number of computers they can support in their data center by the actual power available to the data center. Therefore, reducing your power consumption also allows you to support more physical computers while using the same amount of power, or less power, than before.

Such scenarios as above are ideal candidates for consolidation using Hyper-V, the hypervisor-based virtualization technology included as a role of Windows Server 2008 and Windows Server 2008 R2. Hyper-V extends virtualization capability in a number of ways, including:

Virtualization is a key feature of the operating system and helps customers benefit from server consolidation by achieving isolation between virtual machines.

Hyper-V is available in the Standard, Enterprise, and Datacenter editions of Windows Server 2008 and Windows Server 2008 R2. Each edition includes the right to run a different number of simultaneous virtual machines out-of-the-box: one on Standard, four on Enterprise, and an unlimited number on Datacenter. Additional licenses can also be purchased and added to a Standard or Enterprise installation at any time.

To quantify the power savings made possible by virtualization, Microsoft conducted a series of power usage tests on standalone servers and Hyper-V servers hosting multiple virtual machines, and compared the results. The configurations and test scenarios used for this paper are for illustrative purposes only, and are not meant to be recommendations for your specific environment. Different server roles may require different resources. For example, memory would be the key resource needed for a web workload, while disk capacity might be more important for file services or SQL. It pays to profile your own systems and the services you hope to provide before you adopt any particular configuration.

For these tests, Windows Server 2008 with the Hyper-V role was installed on the enterprise-class server used in the previously referenced tests, and configured with 4 virtual machines, each running Windows Server 2008 and IIS7. Each individual virtual machine was simultaneously subjected to a load generated by 20 active clients, and the power consumption of the physical server was monitored. The test was then repeated with 10 virtual machines running simultaneously. These tests could have equally been performed on Windows Server 2008 R2; however, this product was in early beta at that time.

Comparing the standalone IIS configuration to the Hyper-V configurations reveals much more significant power savings that can be realized through virtualization. The physical server consumed 517.6 watts on average while running four virtual IIS machines, just 3.5 percent more power than it used when configured as a standalone IIS machine.

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 four virtual machines means saving the equivalent power output of three physical servers; running 10 virtual machines means saving the equivalent power output of nine physical servers. Adding four physical IIS servers with the same hardware profile used in the tests would consume more than 17,000 kilowatt-hours of electricity per year; adding 10 physical servers would consume almost 44,000 kilowatt-hours of electricity per year. The difference adds up to thousands of dollars a year at current electricity rates.

Saving power also means reducing the amount of CO2 your data center contributes to the atmosphere. A single Hyper-V server with 10 virtual IIS servers can reduce your CO2 output by more than 30 metric tons compared to the output of 10 physical servers with the same hardware profile. In carbon terms, this is the equivalent of burning 1,500 liters of gasoline, rather than 14,000 liters (or 396 gallons rather than 3,698 gallons).

In addition to its beneficial effects on the environment, this reduction can translate directly into revenue in jurisdictions that engage in carbon trading. At the current market rate of about €25 per metric ton for European carbon allowances, even this modest Hyper-V deployment could free up carbon credits worth €750, or more than US$1,100, every year.

The potential power savings provided by Hyper-V virtualization are clear and significant. This is vividly illustrated by the results of the tests described above, which found that the power usage of a single Hyper-V server hosting four or 10 virtual machines did not differ significantly from the power usage of the same server when hosting a single instance of IIS7, all while maintaining comparable performance. With four virtual machines on a single host, the power usage per server is effectively one-fourth, and with 10 it is effectively one tenth. Organizations could see even more dramatic savings by increasing the number of virtual machines running on each physical host, as performance considerations allow.

In scenarios where continuous full power is not a requirement, Windows Server 2008 and Windows Server 2008 R2 processor power management settings can be implemented on Windows servers and desktops using Group Policy Objects (GPOs). This would allow an administrator to easily implement an enterprise-wide and centrally controlled power-saving scheme.

To take advantage of the advanced CPU throttling features of Windows Server 2008 and Windows Server 2008 R2, your CPU and BIOS must comply with the ACPI specification for processor performance states. Consult your hardware manufacturer’s documentation to determine if your CPU and BIOS are capable of supporting multiple P-states, and, if so, how to enable the feature. If your current hardware cannot support multiple P-states, you may still be able to take advantage of other power-management features in Windows Server 2008 R2.

Enterprise users often leave their computers on overnight, either by choice or to comply with IT policy. This can allow administrative tasks like disk defragmenting, virus scanning, and software update downloading and installation to execute without disruption. However, leaving desktop computers on at night and on weekends can waste thousands of kilowatt-hours of electricity every year even in small and medium-size organizations. Using Windows Server 2008 or Windows Server 2008 R2 and Group Policy, you can centrally manage the power policy of compatible client workstations running Windows Vista and Windows 7, which includes the same power-management features that have been introduced in Windows Server 2008 and Windows Server 2008 R2. For example, you can configure computers to automatically enter a sleep state after a specified period of inactivity, and you can use PPM power policy to specify the range of P-states at which the client can operate.

In contrast to the limited selection of power-management options available in the Microsoft Windows XP Power Options Properties dialog, the Power Options dialog in Windows Vista offers direct control over a much greater number of options, including:

Windows Server 2008 R2 makes it easy to create, distribute, and manage policy for Windows XP, Windows Vista, and Windows 7 clients across the entire spectrum of devices that each can manage. The combination of Windows Server 2008, Windows Server 2008 R2, and Windows Clients offers administrators the greatest potential and greatest flexibility in implementing power-saving policies.