Dark Wake and Data Centers - Green Tech HIghlights

Green technology energy efficiency inventions relating to saving power in the digital world are increasingly important in light of the latest information on data center electricity use:

• Electricity used by data centers worldwide increased by about 56% from 2005 to 2010 instead of doubling (as it did from 2000 to 2005), while in the US it increased by about 36% instead of doubling.


• Electricity used in global data centers in 2010 likely accounted for between 1.1% and 1.5% of total electricity use, respectively. For the US that number was between 1.7 and 2.2%.


• Electricity used in US data centers in 2010 was significantly lower than predicted by the EPA’s 2007 report to Congress on data centers. That result reflected this study’s reduced electricity growth rates compared to earlier estimates, which were driven mainly by a lower server installed base than was earlier predicted rather than the efficiency improvements anticipated in the report to Congress.

(Source:  Jonathan Koomey. 2011. Growth in Data center electricity use 2005 to 2010. Oakland, CA: Analytics Press. August 1.  http://www.analyticspress.com/datacenters.html)

Both the U.S. Department of Energy and Gartner research revealed that the cost to power a typical server over its useful life can now exceed the original capital expenditure. Gartner notes that it can cost over $50,000 annually to power a single rack of servers.  The challenge being how to optimize servers so that you have the capacity for peak demand while avoiding using excessive energy during low demand periods.

Virtualization changes the energy use game but just a little.  Virtualizing as many servers as possible can increase overall utilization from around 10 percent (typical of dedicated servers) to between 20 percent and 30 percent, according to Clemens Pfeiffer, CTO of Power Assure.

Enter the dark wake.

Using dark wake technology the CPU and the network connections remain awake.  Dark wake technology differs from both full power mode and from sleep mode.  Using a dark wake approach,  the computer system powers up components necessary to maintain the network state, e.g., a CPU and a network interface. The computer system then renews the network state (e.g., renews an IP address lease from a DHCP server or other network connection) or otherwise updates a network state (e.g., sends/receives data to/from another networked device).  The computer system consumes more power than in sleep mode because of its use of a CPU/core and network interface, but is not required to resume a full power (awake) mode to maintain the network state or otherwise terminate the network state before or during a sleep state.  In short the server uses the power for only those components needed to maintain the network capability while not incurring power expense for the components that aren't.

Dark wake technology was patented by Apple under the USPTO Green Technology Pilot Program. US Patent 7,996,694 was granted on 08/09/11. To learn more about the energy efficiency patents granted under the Green Technology Pilot Program get the Green Tech Discover and Analysis Report.