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PUE Reconsidered Utility + Limitations of PUE / DCiE as a Datacenter Efficiency Metric

PUE Reconsidered

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Page 1: PUE Reconsidered

PUE ReconsideredUtility + Limitations of PUE / DCiE as a Datacenter Efficiency

Metric

Page 2: PUE Reconsidered

PUE Reconsidered

• Historical Basis for PUE – what is the problem?

• Strengths of PUE Metric – what does it measure?

• Weaknesses of PUE Metric – what does it omit?

• Bottom Line: How to be Strategic About Datacenter Efficiency

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Utility + Limitations of PUE / DCiE as a Datacenter Efficiency Metric

Page 3: PUE Reconsidered

Open Secret: Datacenter electrical costs are skyrocketing…

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$ B

I L

L I

O N

S

M I

L L

I O

N S

O F

S E

R V

E R

S

Page 4: PUE Reconsidered

…fueled by an explosion in power / heat densities

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Page 5: PUE Reconsidered

Industry groups + vendors propose a wide range of solutionsIT equipment Cooling & moving air

► virtualization

► power save mode

► consolidation

► upgrade technology

► decommission servers

► move apps/jobs to virtualized servers and shut down servers

► batch processing during off-peak

► avoid overcooling

► minimize humidification

► reduce air mixing via hot/cold air separation

► blanking plates to minimize recirculation

► raised floor grommets to reduce bypass airflow

► optimize floor layout (CFD)

► closely couple supply and returns to the load

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Page 6: PUE Reconsidered

But first, we need to understand the problem…

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Source: EYP Mission Critical Facilities Inc., New York

Typical Real-World Energy Allocation

in Today’s Datacenter

Page 7: PUE Reconsidered

…so The Green Grid proposed PUE as a benchmark in Feb’07

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“Green Grid Data Center Power Efficiency Metrics: PUE and DCiE”; by Christian Belady, et. al.; www.thegreengrid.org

PUE =Power UsageEffectiveness

=Total Facility Power

IT Equipment Power

DCiE is the exact same thing, but expressed as an inverse:

DCiE =Datacenter

InfrastructureEfficiency Total Facility Power

IT Equipment Power=

1

PUE=

Page 8: PUE Reconsidered

PUE is extremely valuable as a broad efficiency ratio…

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PUE =Power UsageEffectiveness

=Total Facility Power

IT Equipment Power

PUE =1 MW

0.5 MW= 2.0

“My total facility consumes 2x the power of the IT equipment load.”

DCiE =PUE

1= 0.5

“Roughly 50% of the power in myfacility is used to power IT equipment.”

EXAMPLE: Typical 1MW Facility

Page 9: PUE Reconsidered

… and has become a de facto standard metric

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Sun Microsystems

Microsoft Google

• Dueling Press Releases (e.g. Google and Microsoft)• EPA Datacenter “Energy Star” Program• Department of Energy (DOE) “DCPro” Tool and Survey

Page 10: PUE Reconsidered

It’s critical to understand what PUE is, and what it is not!

A relative measure of your plant versus your IT equipment

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PUE =1 MW

0.5 MW= 2.0

• Resilience: Tier I / II / III / IV architecture?

• Trending: How does my efficiency change as IT load changes?

• Diversity: Heterogeneous versus homogenous IT load?

• Utility: Are the servers themselves being used well?

Does not (in and of itself) address:

In short, it does not benchmark the efficiency of the IT component.

Page 11: PUE Reconsidered

Example: Henry’s Super Awesome DatacenterTM (SAD)

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• 1000 servers

• Equipment from every AFCOM sponsor ever

• Located in Reykjavik, Iceland (max temp = 55)

• Placed outdoors under a tented roof

• 24/7/365 operation

PERFECT PUE OF 1.0 !!Every kilowatt is used to power servers. No energy “wasted”.

• Servers completely underutilized

• No critical resilience whatsoever

• No business value or practicality

• Real-world evaluation = complete waste of energy

• All servers dedicated full-time to HenryAndHisCat.com(Video site featuring footage of me playing with my cat.)

Page 12: PUE Reconsidered

None of the proposed IT initiatives (on left, below) improve PUE

IT equipment Cooling & moving air

►virtualization►power save mode►consolidation►upgrade technology►decommission servers

extra savings on cooling

►move apps/jobs to virtualized servers and shut down servers

►batch processing during off-peak

►avoid overcooling►minimize humidification►reduce air mixing via hot/cold air

separation►blanking plates to minimize recirculation►raised floor grommets to reduce bypass

airflow►optimize floor layout (CFD)►closely couple supply and returns to the

load

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PUE =Power UsageEffectiveness =

Total Facility Power

IT Equipment Power

Page 13: PUE Reconsidered

Green Grid recognizes that PUE is not a panacea

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Proposed: In the long-term, create a business-oriented metric

Proposed: Three “levels” of PUE sophistication

DCP = DatacenterProductivity

=“Useful Work”

Total Facility Power

Page 14: PUE Reconsidered

To solve the real problem, we need to measure it…

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Uptime Institute, “4 Metrics That Define Data Center Greenness”

Page 15: PUE Reconsidered

… including environmental information

15Source: ASHRAE, “Thermal Guidelines for Data Processing Environments”

Page 16: PUE Reconsidered

Real-world user examples where better info = energy savings• World’s Largest Networking Company

• Goal: reduce 25% carbon emissions by 2012• Problem: test labs account for more than 80% of corporate energy consumption• Solution: automate shutdown of test equipment when not in use;

provide detailed, comprehensive energy savings data for all labs in enterprise.

• Largest European Bank• Goal: quantify exact power costs for each business application in datacenters• Problem: no reliable, real-time energy data exists for individual servers • Solution: rack PDU’s that provide detailed power + environmental monitoring data for

each receptacle in the cabinet.

• World’s Largest Software Company• Goal: Provide state-of-the-art data center for customers to perform live integration

testing of application suites.• Problem: Need to reboot servers remotely; and understand real-time power

consumption of each customer’s test configurations• Solution: high-security intelligent rack PDUs with remote switching and energy metering.

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Page 17: PUE Reconsidered

Gather data beyond PUE to enable tangible efficiency actions

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Important Solution Attributes:• Open standards / vendor agnostic

• Trended information over time

• Energy data (kwh), not just current (amps)

• Energy data per IT device (not just for rack)

• Product configs to fit all rack densities

• Make sure facilities is happy (UL489)

• Use what you have!

Page 18: PUE Reconsidered

Gather data beyond PUE to enable tangible efficiency actions

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Important Solution Attributes:• Open standards / vendor agnostic

• Trended information over time

• Energy data (kwh), not just current (amps)

• Energy data per IT device (not just for rack)

• Product configs to fit all rack densities

• Make sure facilities is happy (UL489)

• Use what you have!

Page 19: PUE Reconsidered

Summary• PUE is valuable (and widespread) as a high-level metric

• You must understand the pros / cons of PUE to properly evaluate industry, vendor, and press claims

• PUE is not sufficient to improve efficiency tactically

• Datacenters can only be optimized when the energy chain is fully understood / instrumented:

• the appropriate measurements;• at a sufficient level of detail;• trended over time;• easily interpreted;• at incremental CapEx cost;

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Page 20: PUE Reconsidered

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Page 21: PUE Reconsidered

Thank You!

Henry Hsu • Raritan, Inc.

Solutions Consulting, Datacenter Efficiency

[email protected] • (732) 764-8886 x1273