Server Energy Use Evaluation –Discussion Document (Update)June 2011
The following discussion reiterates EPA’s goals in assembling a dataset for Computer Servers, provides moredetails on the type of data of interest, and reflects stakeholder feedback received through the month of May. This
document does not reflect any changes in the scope or intent of the dataset assembly process but is provided forfurther clarification to industry stakeholders.

Testing Overview
Goals for Computer Server Dataset
As noted in a similar memorandum in late February, EPA’s scope for this effort includes 1-2 socket servers, bladeservers and 3-4 socket servers. EPA intends to use the dataset under the following goals:•••

Evaluate the newly proposed structure for product families. The five-point structure proposed in
March is discussed further in this document, along with comments received from stakeholders.
Evaluate manufacturer power calculators as a data source. Stakeholders raised the possibility ofleveraging the existing data models manufacturers use to map expected power consumption of end
configurations. At the meeting on March 11, EPA asked that stakeholders take the first step of comparing
actual laboratory test data ("physical test data") to output from power calculators. Some stakeholders
expressed their intent to do so and EPA encourages further related efforts.
Evaluate adders. Data from single variable testing deviations, where one feature or technique is altered
between tests on an otherwise consistent server configuration, should allow for investigation of theallowances provided for above-base functions.

As is consistent across the ENERGY STAR program, the dataset will be assembled with voluntary input frominterested stakeholders, masked to remove identifying information for the system manufacturer, and thenanalyzed, with opportunities for stakeholder comment.
Five-point Server Product Family Structure
In a memorandum distributed on February 23, 2011, EPA proposed a five-point family structure (Figure 1) for
Server product families. Based on the general support for the proposal received in stakeholder feedback, EPA
intends to proceed with this structure as the foundation for the dataset assembly.
Stakeholders suggested small modifications to the definitions for product families: (1) “Machine Type” was asuggested addition to the Common Product Family Attributes; (2) Power Supply Rated Output was recommended
as a variable that could change between the representative tests; (3) wording to clarify commonalities across afamily’s processor options were suggested; and (4) processor socket power was suggested as an additional
defining element for the representative test scenarios. These suggestions are reflected in the updated definitions
provided below and identified with tracked revisions.

Common Product Family Attributes: A set of features common to all models/configurations within a product family thatconstitute a common basic design. All models/configurations within a product family must share the following:oBe from the same model line or machine type;o

Share the same form factor (i.e., rack-mounted, blade, pedestal);oShare processors either from a single defined processor series or processors that plug into a commonsocket.

oshare PSUs with both the same rated maximum output and greater than or equal to the rated efficienciesy of
the tested configurations at all required load points specified in Section 3.2 (i.e., 10%, 20%, 50%, and 100%for single-output; 20%, 50%, and 100% for multi-output).
Page | 1Product Family Tested Product Configurations: This product family proposal requires five tests to define a productfamily. The variations listed here are explained within the context of an example product family shown in Figure 1,below.
ooPurchase Consideration Variations:Low-end Performance Configuration: The combination of Processor Socket Power, PSUs, Memory,
Storage (HDD/SDD), and I/O devices that represents the lowest-price computing platform within
the Product Family.

High-end Performance Configuration: The combination of Processor Socket Power, PSUs,Memory, Storage (HDD/SDD), and I/O devices that represents either the highest-price or highestperformance computing platform within the Product Family.

Typical Configuration:
oTypical Configuration: A product configuration that lies between the Minimum and Maximum Powerconfigurations and is representative of a product with high volume sales.

Power Utilization Variations:
Minimum Power Configuration: The minimum configuration that is able to boot and executesupported OSs. The Minimum Configuration contains the lowest Processor Socket Power, least
number of installed PSUs, Memory, Storage (HDD/SDD), and I/O devices, that is both offered forsale and capable of meeting ENERGY STAR requirements.

Maximum Power Configuration: The vendor-selected combination of components that maximize
power usage within the Product Family once assembled and operated. The Maximum
Configuration contains the highest Processor Socket Power, greatest number of installed PSUs,
Memory, Storage (HDD/SDD), and I/O devices that is both offered for sale and capable of meeting
ENERGY STAR requirements.

Figure 1: Product Family Testing

High-end – Minimum Configuration

High-end – Maximum Configuration

This test point is likely to be a
performance-oriented system outfittedwith the least number of components
available in the family.

This test point is likely to be a
performance-oriented system outfittedwith the greatest number ofcomponents available in the family.

Typical Configuration
Δ Purchase
Considerations

The vendor-selected components that
represent highest-volume deployedconfiguration.

Low-end – Minimum Configuration

Low-end – Maximum Configuration

This test point is likely to be a costconscious system outfitted with theleast number of components available
in the family.

This test point is likely to be a costconscious system outfitted with thegreatest number of components
available in the family.
Δ PowerPage | 2

Dataset Contents
To address the goals for the dataset, EPA plans include system-level data, relevant data from power calculators(described further in the next section), and component Idle Power data.
•••

System-level test data. The primary area of interest, Full Load and Idle Power data resulting from actuallaboratory testing will be the foundation of the dataset.
Power calculator data. Full load and Idle power derived from power calculators will be used primarily forinvestigating component idle power. Based on the outcome of comparisons between calculator data andphysical test data, it may also be used to supplement five-point physical test data.
Component Idle Power data. To better understand the impact of component choices on system power
consumption, EPA will welcome power draw data at Idle and optionally at Full Power for add-incomponents. The primary focus will be on I/O, which stakeholders have suggested may need review
based on experiences with Version 1.0 adder amounts.

Permutations of Interest
As noted in the February memorandum, EPA is interested in evaluating the testing permutations listed below at aminimum.
•Processoro Choose base configurations with processors for each available core count per socket and rated
power that represent, at a minimum, the highest and lowest available rated system speed (FSB).
This processor shall be used across a set of typical, maximum, and minimum testing runs.
o For the typical configuration, test the same configuration with a processor socket unpopulated (ifoffered as an option to customers).

•PSU – Choose power supply options that represent typical options for customers (if applicable, selectboth PSUs optimized for efficiency and standard models). PSUs should be selected using a
manufacturer’s standard practices, with a brief, written rationale/explanation of why the PSUs wereselected for each configuration accompanying power data (e.g., PSU was tuned to Full Load Power of theconfiguration, PSU is the only option available across the family).

•HDD or SSD – Include storage elements that represent a range of customer preferences (i.e., highperformance HDDs versus high efficiency HDDs, etc.).

•Memory (DIMM) – Consider testing several vintages of memory technology such that EPA can evaluate
the impact of new memory technologies on overall server efficiency.

•I/O Device – Provision systems with minimal I/O add-in cards; for testing, ensure the server offers at least
one Ethernet port (using a single add-in card only if no onboard Ethernet support is offered). EPA
welcomes device-level power information on I/O devices to build on the existing I/O dataset from Version
1, available at
http://www.energystar.gov/ia/partners/prod_development/new_specs/downloads/servers/Final_Draft_Ser
ver_IO_Data_Set.xls.

Blade Testing
In the February memorandum, EPA stated its intention to test blades using an N-1 approach: a half-filled chassisof homogeneous blades would first be tested for Idle and Full-load Power, with a single blade removed for asecond test in order to calculate the per-blade power value. At the subsequent meeting with stakeholders,
response was mixed between support and suggestions for a return to EPA’s previous proposal of a separate
single-blade test. EPA asked at the meeting that stakeholders follow up with written description of the desired
testing model. No written comments on this point were received, and EPA is proceeding with the N-1 testing
approach.

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The following testing guidelines for Blades reflect other comments received from stakeholders on blade testing
after publishing of the February memorandum. In summary, these were: (1) an option should be provided for fullchassis testing should a manufacturer choose this over a half-filled chassis; (2) the same blade configuration
should be used among all blades in a test.
••••

Chassis population: A fully-populated blade chassis may be optionally tested instead of a half-populatedchassis. The half-populated chassis scenario remains the default and the only other accepted option in
the dataset.
Blade Server configuration for a single test point: All blades must share the same configuration(“homogeneous” blade selection).
Blade Server configurations among the five test points: The Blade Server configurations shouldreflect the general guidelines provided for each of the five test points. For example, the High-end –Maximum Configuration would involve a half (or fully) populated chassis with all configurations
representing a performance-oriented system with the greatest number of components offered in thefamily.
Characteristics to identify when recording test results:o Form factor would be added: e.g., single-wide, double wide, half-height

The testing process is otherwise as described in EPA’s February testing memorandum.
Other comments were received on the format of requirements, such as using the qualification model in place for3S and 4S Servers, considering variations in overhead from different vendors chassis, allowing Blade Chassis
and Blade Servers qualified in independent tests to be considered qualified when combined. EPA will take these
into account, but does not feel they impact the initial step of developing a dataset for Blade Servers.

Role of Power Calculator Data
ENERGY STAR will accept a combination of both physical test data and calculator data. EPA strongly
encourages manufacturers to submit physical test data, but understands that time and resource constraints will
make calculator data more readily available in many situations.
EPA anticipates the following uses of calculator data, in order of value:
1. Correlating output of calculators to physical test data to compare results and understand the variation
between laboratory testing and power-predicting models.
2. Evaluating the impact of single-variable changes in components by comparing simulated calculator datawith base physical test data.
3. Supplementing physical test data once the relationship between power calculator predictions and physicaltest data is better understood.
Comparing Sources
Before submitting data from calculators, EPA asks that manufacturers take existing test data from ENERGYSTAR qualified units, compare it to calculator-generated data for those same units, and analyze and report toEPA the results for calculator biases. EPA also encourages manufacturers to compare calculator data to physicaltest data from non-ENERGY STAR models where possible.
Single Variable Changes
To examine the effects of single component permutations (i.e., PSU choice, storage type/capacity/spindle speed,
vintage/quantity/density of installed memory, I/O technology), EPA believes that calculator data could provide aneffective balance between broad insight and testing burden. EPA strongly encourages physical testing wherepossible for comparison purposes.
Supplementing Physical Test Data
To provide insight into the effect of the 5-point family definition, EPA intends that data in each of the five points bePage | 4

collected from physical testing. EPA encourages manufacturers to enhance these tests as desired with calculator
data for configurations outside the five physical tests.

Manufacturers should contact EPA to discuss their calculators, the results of their calculator bias analyses, and toidentify any issues that may arise from the use of their calculators in data generation. If any of the above
guidelines conflict with what you understand to be the aim, scope, or methodology of the ENERGY STAR Servers
data assembly process, please contact RJ Meyers at Meyers.Robert@epa.gov or (202) 343-9923 or contact Evan
Haines at ehaines@icfi.com or (781) 676-4081 with your concerns.

Development Timeline Update
Based on stakeholder feedback, EPA has updated the development timeline.

Project PhaseData assembly

JuneJuly

AugustSeptember OctoberNovember December January

February MarchAprilMay

1/2SBlades
3/4S
Data analysis
1/2SBlades
3/4S
Specification Revision
Draft 1
Draft 2
Final draft
Published

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