Metric for Server Evaluation: Space, Watts and Power

Sun Microsystems

SWaP (Space, Watts and Power) is the new standard for calculating server efficiency before you buy. This metric that allows you to calculate the impact of a server in your data center.

How SWaP Works

Server A Server B Server A Difference Performance 500 operations 500 operations Equal Space 2RU 4RU x2 smaller Power 300 Watts 800 Watts x2.7 less SWaP Rating 0.83 0.16 x5.2 more

In the example above, Server A and Server B produce equal performance, however Server A is half the size and less than half the power of Server B. Using the SWaP formula, it is revealed that Server A is over 5X more efficient than Server B–providing a huge impact to rack dense deployments in your data center.

Source: SWaP (Space, Watts and Performance) Metric, Sun Microsystems, 2008

In a report published by David Greenhill, Distinguished Engineer at Sun Microsystems, (Space Watts and Power), he indicates that older model servers can consume 45 times the energy of  newer models.  In his case study the 1997 server used 13,456 watts / hr. compared to only 300 watts / hr. for the 2005 server.    But even 300 watts/hr. (0.3 Kw/hr.) add up quickly when you realize you’re typically running it 7/24/365.  In fact, each 300 w server uses about 2600 Kw per year.  Then you factor in the hundreds or even thousands of servers most large organizations are using and the air conditioning, UPS, lighting, etc. to house them, and you can start to see why less is definitely more.

Source: “Green IT Innovation – Data Center Efficiencies to Reduce Cabon Footprint – Part 1.”, Blog – Sharing Sustainability Innovation, December 19, 2008, http://globeforum.wordpress.com