What is Sustainable ?

This post authored by Jay Reddy – Dell Server Engineering

Whenever I see someone use the word ‘sustainable’, I am usually unclear on the meaning of the word, and unsure of the intent of the usage.  In my mind the only way of life that seems completely sustainable is subsistence farming; let me hasten to add that as much as I love to garden, I have no interest in subsistence agriculture as a livelihood.  I am just content that I have a professional existence that allows me to play a part in designing some of the most energy efficient server computers in the marketplace.  The number one contributor to greenhouse gas emissions is power generation, and the fastest growing users of power are datacenters.  The bright spot here is that one of the fastest growing datacenter server categories is one commonly called blade servers.  Blade servers contribute to fewer emissions when compared to stand alone servers in a couple of ways, one is by reducing waste during upgrade cycles, the other is by making more efficient use of their power supplies and fans.


When a new generation of Intel servers debut, they have higher computational performance than their predecessors, but they may not be better in other ways, and certainly there is minimal improvement in the quality of the steel used in the chassis.  Blade servers allow one to upgrade the computational elements on a different cycle than the other elements in the chassis, and leave the chassis in place for several generations of servers.  While computer chips require an astounding amount of energy to manufacture, refining steel is pretty energy intensive too; so not having to recycle the chassis has an impact.   All servers have power supplies, and power supplies like most machines operate most efficiently in a particular load range.  An example of this in the car world is the soon to be available Chevy Volt that has an engine that operates at a constant speed to drive a generator, hence achieving outstanding fuel efficiency.  In a server what this principle translates to is that as the demand for a server rises and falls, it may at times operate at peak energy efficiency, while being relatively inefficient at other times.  In a blade server chassis a pool of power is used by a number of servers, hence there is an opportunity to balance the load such that the power supplies always operate at their most efficient point.  Of course to make this a reality takes a certain amount of intelligence in the chassis, outside of the server blades.  The Dell blade, or modular, chassis has myriad low power microprocessors that monitor the performance of the servers, and control the power supplies such that the whole system operates at its most energy efficient point, while providing maximum performance.  All those microprocessors require a lot of code to make them run, which in turn means a lot of smart engineers thinking up equations to turn into algorithms, and writing and testing the code.  The work is demanding but ultimately rewarding when you see the product you helped create, demonstrate the best performance per watt, in the marketplace.


One of the perks of being an engineer in the information age is the ability to see how others engineers are solving problems similar to your own.  An example is the development of fans for Dell’s modular server chassis.  Jet engines are basically fans, the more air a jet engine can move for a given quantity of fuel the more likely it is to be bought by aircraft makers, and airlines.  Since small improvements in efficiency of jet turbines can result in substantial savings, a lot of research is done by people that design and build them.  That research in turn helps us build a better fan for our servers.  The fans, just like the power supplies are shared by multiple servers, and controlled by microprocessors to run only as fast as they individually need to, to guarantee maximum performance.  Any time there is a breakthrough in power supply, or fan, technology, we make an improved product available to our customers, and they can benefit from the energy savings with a small upfront investment.  Best of all, when we develop a better algorithm to control all the elements in a chassis, we make it available to our customers in the form of a free software upgrade.  This story should get even better, as we integrate groups like eServ, that joined Dell as part of the Perot acquisition; eServ provides engineering services to the aerospace industry amongst others.


The more I learn about how the choices I make in my life affect the planet, the more complicated those choices seem to get.  I am thankful that at least at work I only need focus on ways to make servers more energy efficient.  

About the Author: Scott Hanson