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Lessons for the Data Center Novice

August 17, 2011
at 9:00 am PST

Early in my days as a Data Center manager I attended a series of talks focused on Data Center energy efficiency.  The sessions covered everything from hardware chip design to application performance to physical infrastructure.

Even for a beginner, two things were immediately obvious.  First, Data Centers consume more energy than other buildings – much more.  Second, with so many different components drawing power there are a lot of opportunities to make a server environment more energy efficient.

One presenter, from a manufacturer of Data Center standby electrical systems, mentioned during his talk that electrical components operate more efficiently at higher loads.  The closer they are to maximum capacity, the better they perform.

I thought about this for a while and at the conclusion of the session, asked:  “If electrical systems operate more efficiently at higher loads, why do operators of Data Centers with redundant electrical infrastructure split the load evenly between the A and B sides?  Why not put the entire load on side A and nothing on side B?  Wouldn’t that be more energy efficient?”

To my surprise, the question stumped the presenter.  Eventually, one of his co-workers in the audience stood up and said they had conducted experiments with that configuration and found that although it was more energy efficient, when a failure occurred on the A side and the full power load (in his words) “came crashing onto the B side,” the components sometimes failed.  The redundant electrical infrastructure could reliably handle a sudden jump from 40 percent loaded to 80 percent, but not from zero to 80 percent.

Oh.  Enter my third Data Center lesson for the day:  energy efficiency is important, but ensuring availability is much more important.

Speaking of availability and Data Center power, this week’s question explores the use of rotary UPS systems that employ flywheel technology versus traditional battery UPS systems.  See below for discussion of the pros and cons of each.

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2 Comments.


  1. Good to see the knowledge sharing,Doug. I read your book on building datacenter a few years back and it was informative on the physical infrastructure piece. I think it would also be informative if you can share some of the experiences or creative ways to increase efficiency when there are macro environment limitations. I mean, outside of a selected few companies (Google, Amazon, Facebook, Amazon), most companies is not able to build datacenter from the ground up, buy the cheapest land near a lake, or negotiate a jaw dropping electricity rate with the local government. What can we do when we need to house 1/2 floor of servers in a 80-year old peering exhcnage that assumes 2 KVA per rack when designed? :-)

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    • Douglas Alger

      Hi, Eric. Thanks for reading – both this blog and one of my books. :)

      That’s an excellent suggestion. I’ll definitely do a future post about optimizing a Data Center in less than optimal conditions.

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