The Truth About Green IT

Virtual resources must still run on physical hardware that must be powered and cooled, and virtual machines are even easier to lose track of than traditional one-server/one-application implementations. VM sprawl, the unmanaged proliferation of virtual resources, can result in no new energy savings. Virtualization without effective capacity planning and life-cycle management can easily result in IT departments spending as much or more on utilities.

Thus, green IT requires a holistic approach to data centre and desktop system management that ties business use to resource planning. Simply virtualizing resources does not a green IT solution make.

A September research study by Enterprise Management Associates showed that virtualization was the most popular green IT initiative, but that CPU power throttling, which resulted in 14 percent energy savings on existing equipment, got the highest return on investment.

CPU power throttling has been available—but not often implemented—in server hardware since 2000. This is one piece of low-hanging fruit that IT managers can grasp immediately to yield utility savings now. However, implementing CPU power saving requires, of course, hardware that supports this functionality and an operating system that can implement the technology.

Achieving a state of green IT means setting a measurable goal of computation work performed per watt consumed. Finding performance price per watt is as much art as science. IT managers will have to play a significant role in determining how to measure workloads, especially for servers, desktops and laptops. This is especially true for servers that are used in a virtualized environment.

The Green Grid has published a useful paper titled “A Framework for Data Centre Energy Productivity.” The paper discusses the pros and cons of using CPU utilisation as a measure of computing work per watt consumed. For IT managers, the most important aspect of this discussion is to ascertain, based on knowledge of the server application workload, what is the most useful metric for a server, and then to implement a measurement and reporting mechanism.

For network and storage equipment, the measurement of work per watt consumed is clearly related to capacity and bandwidth processed over a given period of time.

There is a battle brewing among network equipment vendors that is based in part on the greenness of their products. It is important for IT managers to test network equipment in a production environment to get accurate numbers of performance per watt.

While some vendors provide information on network equipment at various load levels, these tests are almost always performed using test loads for relatively short durations.