“We Can’t Afford to measure PUE”

One of the more interesting phenomena that I experience as I travel and talk with customers and industry peers is that there is a significant number of folks out there with the belief that they cannot measure PUE because they cannot afford or lack the funding for the type of equipment and systems needed to properly measure their infrastructure.  As a rule I beleive this to be complete hogwash as there are ways to measure PUE without any additional equipment (I call it SneakerNet or Manual Scada).   One can easily look at the power draw off the UPS  and compare that to the information in their utility bills.  Its not perfect, but it gives you a measure that you can use to improve your efficiency.  As long as you are consistent in your measurement rigor (regular intervals, same time of day, etc) you can definitely achieve better and better efficiency within your facility.

Many people have pushed back on me saying that measurement closer to the PDU or rack is more important and for that one needs a full blown branch circuit monitoring solution.   While to me increased efficiency is more about vigilance in understanding your environment I have had to struggle with an affordable solution for folks who desired better granularity.

Now that I have been in management for the better half of my career I have had to closet the inner geek in me to home and weekend efforts.   Most of my friends laugh when they find out I essentially have a home data center comprised of a hodge podge of equipment I have collected over the years.  This includes things like my racks of different sizes (It has been at least a decade since I have seen a half-height rack in a facility, but I have two!) , my personal Cisco Certification lab, Linux Servers, Microsoft Servers, and a host of other odds and ends).  Its a personal playground for me to try and remain technical despite my management responsibilities.  

Its also a great place for me to try out new gear from time to time and I have to say I found something that might fit the bill for those folks that want to get a deeper understanding of power consumption in their facilities.   I rarely give product endorsements but this is something that the budget minded facilities folks might really like to take a look at. 

I received a CL-AMP IT package from the Noble Vision Group to review and give them some feedback on their kit.   The first thing that struck me was that this kit seemed to essentially be a power metering for dummies kit.    There were a couple of really neat characteristics out of the box that took many of the arguments I usually hear right off the table.


First the “clamp” itself in non-intrusive, non-invasive way to get accurate power metering and results.   This means contrary to other solutions I did not have to unplug existing servers and gear to be able to get readings from my gear or try and install this device inline.  I simply Clamped the power coming into the rack (or a server) and POOF! I had power information. It was amazingly simple. Next up -  I had heard that clamp like devices were not as accurate before so I did some initial tests using an older IP Addressable power strip which allowed me to get power readings for my gear.   I then used the CL-AMP device to compare and they were consistently within +/- 2% with each other.  As far as accuracy, I am calling it a draw because to be honest its a garage based data center and I am not really sure how accurate my old power strips are.   Regardless the CL-AMPS allowed me a very easy way to get my power readings easily without disrupting the network.  Additionally, its mobile so if I wanted to I could move it around you can.  This is important for those that might be budget challenged as the price point for this kit would be incredibly cheaper than a full blown Branch Circuit solution. 

While my experiment was far from completely scientific and I am the last person to call myself a full blown facilities engineer, one thing was clear this solution can easily fill a role as a mobile, quick hit way to measure PUE power usage in your facility that doesn’t break the bank or force you to disrupt operations or installing devices in line.   


Author: mmanos

Infrastructure at Scale Technologist and Cloud Aficionado.

One thought on ““We Can’t Afford to measure PUE””

  1. Totally love this post! So many vendors pitch expensive solutions requiring monitoring of every point in your datacenters, but just get started already! We have used clamps to measure power in this way, and also simple notation of the peak load UPS etc. This is a first step and if you begin presenting it to your management on a monthly basis, or daily basis if you can get it done, this is a good way to get buy in to implementation of further solutions.

    Anyone can do a quick measure of their PUE, and capture it daily.

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