Tag Archives: pue

Finally, proof positive that PUE is garbage.

Vern Burke, SwiftWater Telecom
Biddeford, ME

I’ve just been reading a piece about Microsoft removing fans from their data center servers and that having a negative effect on their PUE numbers. I’ve written on this blog before about the problems with PUE, now we have proof that it needs to be put out of it’s misery.

In a nutshell, PUE is the ratio of power consumed by the IT equipment of the data center, versus the entire power consumed by the data center. A PUE of 1.0 would indicate a data center where all the power is being consumed by the IT equipment. A PUE greater that 1.0 indicates a data center where a certain amount of power is being consumed by other than IT equipment, the biggest chunk of which is cooling.

The problem I’ve written about before with PUE is the failure to take into account the actual work being accomplished by the IT equipment in the data center. Throw in a pile of extra servers just simply turned on and idling, not doing anything useful, and you’ve just gamed your PUE into looking better.

The problem shown here is even more damning. Microsoft determined that data center energy consumption could be reduced by removing the individual cooling fans from its servers and increasing the size of the data center cooling system. Since the increase in power for the data center cooling systems is less than the power required for the individual server fans, the data center accomplishes the same amount of work for less total energy consumption, an efficiency win in anyone’s book.

The side effect of this is that, even though the total energy consumption for the data center is reduced, transferring the energy usage from the fans (part of the IT equipment number) to the cooling (part of the non-IT equipment number) makes the PUE for the data center look WORSE.

Gaming the metric simply made it inaccurate, which was bad enough. Any efficiency metric that shows a net gain in data center efficiency (same amount of work accomplished for less energy consumed) as a NEGATIVE is hopelessly broken. This also has the side effect of making a mockery of the EPA’s Energy Star for data centers, since that award is based directly on the data center’s PUE.

Misleading, inaccurate, and now totally wrong, this sucker needs to go where all the other bad ideas go to die.

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Thursday data center tidbits: gold plated SSD, more crazy data center metrics

Vern Burke, SwiftWater Telecom
Biddeford, Maine

First up today is the piece about LSI releasing a 300GB SSD solid state drive for almost $12,000. The speed is certainly impressive but is it really worth the price premium between a sub $100 traditional hard drive vs a $12K SSD of the same capacity?

The next piece is about the new data center metrics from The Green Grid, CUE (carbon usage effectiveness) and WUE (water usage effectiveness). Instead of taking the opportunity to create some truly useful and accurate metrics, they’ve created two that suffer from exactly the same faults as PUE (power usage effectiveness), namely that they do not take into account actual work being produced and are ridiculously easy to game. I’ll give The Green Grid credit for swinging, but this is the second and third whiffs in a row.

Finally, we come to more what if cloud computing security hysteria.
From the article comes the quote “What if the service you’re using merges with another company or goes bankrupt?”. Um, exactly the same thing if your co-location provider merges or goes bankrupt. This is NOT a cloud computing specific issue. The “users are uneasy about it” line is NOT valid evidence that there’s anything wrong at all with cloud computing security.

Email or call me or visit the SwiftWater Telecom web site for green data center services today.

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Tuesday data center tidbits:unclear on the concept, micro PUE jumps the shark

First up today is this piece about the top 10 data center annoyances. Now, I can certainly agree with a complaint about bad lighting levels and lousy housekeeping, but crabbing because you’re uncomfortable working in the hot aisle misses the point. The hot aisle works just fine for the servers and that’s why it’s there, not for your comfort, so suck it up.

Data center quote of the week, from this article on “micro PUE”:

“Inventing the term ‘Micro PUE’ seems to me to be an extreme case of riding the PUE bandwagon a little too far …”

More like a LOT too far.

Email or call me or visit the SwiftWater Telecom web site for green data center services today.


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Monday data center tidbits: generator smog and misusing PUE (again)

First up is the piece about Quincy WA dithering about the environmental impact of data center backup generators. I’ve got news for someone, if you’re running the generators enough to cause a blip in the health of the local area, you probably should be considering a different location because that means the commercial power is WAY bad.

Next piece is about Digital Realty talking about PUE and efficiency. The comment of note here is that they determined the initial PUE from the load bank testing. How in heck could you get a meaningful PUE from load bank testing? Sure, you’re consuming power, generating heat, and removing heat, but the airflow in the data center is not even going to be close to the real IT equipment environment. The fact that that wasn’t close to accurate shouldn’t have come as any surprise.

Finally, from the piece above, we also get the piece of wisdom that you only get good PUE from fully loaded data centers. My own data center, currently loaded at 10% (anyone looking for data center capacity?) averages 1.2 and, with the kick off of fall, we’re reusing 100% of the waste heat to heat the rest of the building.

Email or call me or visit the SwiftWater Telecom web site for green data center services today.


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Friday data center tidbits pt 2:who cares about PUE cheating?

In an article about attempting to move from PUE to a new data center efficiency metric, Christian Belady of Microsoft commented:

“There are perceived issues with it, comments about people cheating on PUE reporting. But who cares?”

Let’s see, now that PUE has been enshrined as a competitive marketing metric between data centers, first via marketing fluff, then as the basis for the EPA’s data center Energy Star rating, everyone who operates a public data center should care. I’ve had my conversations with Christian and I’ll be the first one to admit, despite it’s flaws, PUE is a useful INTERNAL metric, but when they start handing out rewards based on it, everyone should care that it isn’t being gamed.


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Thursday data center tidbits: boneheaded data center efficiency statistics and more!

First up today, we have a piece about the EPA’s Energy Star data center rating system. Proving the old saw about lies, damn lies, and statistics, we get:

“Of the numerous variables analyzed, only the annual IT energy consumption was found to be statistically significant in explaining the variation in energy use; data showed that facilities with higher IT energy consumption have lower PUE values, on average. The final regression model predicts a PUE value based on the IT energy.”

This has to be the most ridiculous thing I’ve ever heard. Data centers with high power consumption are expected to get better PUE? Based on what?

So, not only is the measurement a crock (PUE), the target the data center is measured against is conjured out of thin air and about as substantial.

Next is from a piece asking “Is virtualization cloud computing?“. We get this jewel from this reading:

“To continue this analogue, cloud computing can happen without virtualization. Certain hardware, operating system and even application clusters can deliver cloud services. ”

Cloud computing is an extension of virtualization, it’s not possible to separate the two and still have something meaningfully labeled as cloud computing. Sorry, go sit in the corner with everyone else who misuses the term cloud.

Email or call me or visit the SwiftWater Telecom web site for cloud computing services.


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Friday data center tidbits: ghost servers. #datacenter outages, and more!

First up is a piece about what does and what doesn’t work with a green IT strategy. The thing that stood out in this for me was:

“Data center audits inevitably turn up servers with no connections to network cables that remain turned on.”

Anyone who disconnects a server from the data center network and leaves it powered up needs a good swat to the back of the head.

The next piece up is a post from James Hamilton about PUE. As much as I’ve talked here about the flaws in PUE, it’s certainly of some use as an internal metric. The big problem with PUE is trying to compare different data centers based on it, as well as giving out official superiority awards based on it (Energy Star for data centers). It’s probably the most misused metric ever invented.

From the “bozo is contagious” file, we have the recent Bluehost data center outage in Provo, UT. Kudos to Bluehost for actually having a power backup system that worked, squeaky red noses to the local telecom carrier for not only losing Bluehost’s Internet connections but phone service to the whole city as well.


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