@ IDF 2009: Cold Redundancy – A New Power Supply Technology for Reducing System Energy Usage

If you would like to learn about a new power supply technology for reducing server energy usage there is an upcoming IDF session that may interest you. The title of the session is “Cold Redundancy

  • A New Power Supply Technology for Reducing System Energy Usage”. As you can probably guess from the title, we are calling this new technology “Cold Redundancy”. There has been a lot of research done to figure out ways of reducing the input power of a server when it is in an idle state. After all, an idle server is just a very expensive space heater sitting there doing nothing other than consuming energy and producing lots of heat. This is important because some utilization studies have shown that servers can sit idle for a considerable percentage of the time. So anything that reduces the input power of an idle system will have a very significant effect on the overall yearly energy usage - and ultimately save on operating costs.

This presentation will describe, and demonstrate, the cold redundancy technology we have been working on here at Intel® to reduce system idle power.

One great thing about this new technology is that everything can be kept inside the power supply. No changes to the system software will be needed so the only additional requirement to implement this would be using a power supply that has cold redundancy technology inside it. This will make it easy to integrate into systems in the future because it could become a “plug ‘n play” power supply upgrade option.

Since cold redundancy is a power supply technology, I’ll cover some basic concepts to get things started.

There are two different types of power supplies called redundant and non-redundant which are used in computers.

A non-redundant supply has only a single module which provides all the power needed to keep the system operating. This means there is no backup so if the power supply fails, the system shuts down until the supply is replaced. Desktop computers typically have a non-redundant supply in order to keep the costs low.

Most servers on the other hand, have a redundant type of power supply. That means there are extra (redundant) power supplies in the power subsystem so if one supply fails the server will continue working normally. This is for applications where getting maximum system uptime and reliability are worth the additional cost of putting in the redundant supplies. In a case like this though, the redundant supplies are not really needed until one of the supplies actually fails. The drawback with having the redundant supplies turned on until needed is that the supplies still use a lot of power which increases the system operating costs.

Cold redundancy reduces system idle input power by putting these redundant supplies into an almost off (standby) condition or “cold redundancy” mode, as we call it here at Intel®. Because of how cold redundancy works, the more redundant supplies there are in a power subsystem the more effective it is and the more energy that can be saved. The general idea of powering down redundant supplies is not new, but the problem has always been how to turn the supplies back on fast enough so that system operation is not affected in case of a failure. We have come up with a solution to this problem by developing cold redundancy technology. Cold redundancy has the ability to put the redundant supplies into a standby state to save energy at system idle while still being able to turn them back on fast enough in case of a failure to keep the system operating normally. It really is the best of both worlds, saving energy while maintaining the same system uptime and reliability as conventional redundancy where all the power supplies are running all the time.

If you are interested in learning more, the session number is ETMS001 and will be presented at the fall Intel Developer Forum in San Francisco on September 22nd at 10:15 AM in room 2006 of the Moscone Center. This session will be a combination of lecture and live demonstrations. We decided that having a couple of demos during the lecture would help make the concept more understandable and the presentation more interesting as well. One thing to keep in mind about this session is that we will not be discussing theoretical possibilities or projects planned years in the future but real products that will be available soon.

The live demonstrations use a production ready cold redundancy enabled power subsystem that is being integrated into a product Intel® plans to release in the 4th quarter of this year. It doesn’t get much more real than that. The demonstrations will show how the control logic works and what power and energy savings are actually possible. This will be done by measuring the AC input power to a four module power subsystem and running the same output load profile with and without cold redundancy enabled. By comparing the two input power graphs the advantages of implementing this new technology can be immediately seen and quantified. I think you will find this to be a very interesting and informative session but then I’m probably biased just a little bit. J

Hope to see you there,



Viktor Vogman – Power Architect

Andrew Watts – Test Automation