CSCI PSU Proposal for ENERGY STAR Storage Server Specification

EPA Energy Star for Storage Development Workshop

Kathleen FiehrerCSCI Technical Program Manager

Energy Storage Spec Framework Document

• Power Supply Requirements: EPA stated intentions of exploring a Net Power Loss approach for Computer Storage and Tier 2 Server power supplies. • Approach would aim to specify a maximum allowed

power loss through the power supply at actual operating conditions (e.g., Idle and full load power).

• Alternatives •Specify the minimum efficiency for a power supply under actual use conditions

•Evaluate both Multi-Output and Single-Output power supply efficiency and power factor levels.

ENERGY STAR Motivation for NPL Approach

• ENERGY STAR Goals for Storage PSU requirements • Maximize and promote operational efficiency • Encourage right sizing and address impact of redundancy • Continue to recognize PSU as possible energy bottleneck AND

ALSO opportunity for savings regardless of hardware configuration, work load, or application

• Maintain momentum toward more efficient supplies as mainstream

• Current method does not consider how a PSU is installed and operated in the field.

ENERGY STAR NPL Method • ENERGY STAR has indicated that NPL is a possible

approach for measuring system efficiency rather than current PSU efficiency and PF approach • Measures AC Powerin – DC Powerout at Idle and Max vs current

method DC Powerout / AC Powerin at designated rated loads • Address actual wattage losses at real operating conditions

instead of efficiency at arbitrary load conditions • Directly correlates to wasted wattage / real-world conditions • Eliminate current arbitrary load points of 10%, 20%, 50% and 100%

loading • Includes effects of redundancy and PSU sizing

• Industry opposes • No accepted protocol • Industry aligned behind current methods

Gold PSU Losses vs Losses 0 0.2 0.4 0.6 0.8 1

% Load

180 94%

160 92%

Max

Gol

d PS

U L

osse

s 140 90% 120

88% 100

86% 80

84% 60

500W PSU 82% 40 1200W PSU Gold Eff 80% 20

0 78% 0 200 400 600 800 1000 1200 1400

Output Power 4 proc system operating range

dual proc systemoperating range

Effic

ienc

y

94%0.8 1

% LoadGold PSU Losses Which net loss0 0.2 0.4 0.6

requirement do we use?180

160 92%

Max

Gol

d PS

U L

osse

s 140 90% Option #1120

88%100

86% Option #28084%

60500W PSU 82% 40 1200W PSU Gold Eff 80% 20

0 78%

0 200 400 600 800 1000 1200 1400

Output Power4 proc system operating range

dual proc systemoperating range

Effic

ienc

y

Gold PSU Losses 0 0.2 0.4 0.6 0.8 1

% Load

180 94%

160 Option #1 92%

Max

Gol

d PS

U L

osse

s 140 90% 120 Option #2

88% #1 not as good for100 high power PSUs

86% 80

#1 not as good for 84% low power PSUs60 500W PSU 82% 40 1200W PSU Gold Eff 80% 20

0 78% 0 200 400 600 800 1000 1200 1400

Output Power 4 proc system operating range

dual proc systemoperating range

Effic

ienc

y

Gold PSU Losses 0 0.2 0.4 0.6 0.8 1

% Load

180 94%

160 Option #1 92%

Max

Gol

d PS

U L

osse

s 140 90% 120 Option #2

88% 100 #2 not capable

using low power PSUs 86% 80

84% 60 #2 not capable

500W PSU using high power PSUs 82% 40 1200W PSU Gold Eff 80% 20

0 78% 0 200 400 600 800 1000 1200 1400

Output Power 4 proc system operating range

dual proc system

Effic

ienc

y

operating range

0 10 20 30 40 50 60 70 80 90

100

PS

U lo

sses

(wat

ts)

570 1100 650 460 750

Curve Fitting with NPL Single O/P Gold PSUs (best in rating)

0 200 400 600 800 1000 1200

PSU Load (watts)

Proposed PSU Requirements for Storage Spec • Create three PSU categories for ENERGY STAR specifications

• Single O/P PSU category • Same efficiency and PF requirements as CSCI and 80+ Gold requirement for single O/P PSU

• Measurement excludes fan power • Multi O/P PSU category

• Same efficiency and PF requirements as CSCI and 80+ Silver requirements for multi O/P PSU

• Measurement includes fan power • Multi O/P PSU category for storage

• Efficiency and PF requirements should be based on SNIA’s Green Storage TWG – expected late Oct’2009

• Special consideration that data center storage PSU’s max operating load is 50% of its rated power load.

• Measurement excludes fan power • The storage power supply fan is used to cool the entire storage chassis, not

just the power supply. • Efficiency testing conducted at 230V for all power supplies

• Maintain PSU consistency and alignment for all ENERGY STAR specifications

Proposed PSU Requirements (cont) • Withdraw consideration of system level PSU

requirement – consideration from Tier 2 server • Idle load power specification encourage right sizing

•The definition of idle and storage idle power requirements will need to be refined relative to server requirements

• Use adders to address redundant power supplies • Estimated system NPL based on efficiency curves for

installed power supply • Focus on system level requirements rather than additional

PSU requirements • CSCI supports SNIA and other industry efforts to

develop storage performance/efficiency metrics butrecognizes the complexity of such a metric

•ENERGY STAR needs to move cautiously when defining storage performance and energy metrics given the complexity ofenterprise storage systems.

Proposed Accuracy Requirements for Storage • Accuracy requirement of ±5% accuracy with a

maximum error of ±10W per PSU• As the load decreases the ability to accurately measure

the power becomes increasingly difficult Æ maintain max error of ±10W for loads less than 100W.

• Requirement should be per PSU • Fixed maximum system error becomes increasingly

difficult for systems with redundant and additional PSUs • Eliminate specialized power metering solutions

• Sacrifices additional power losses to accurately measure input power

• Unnecessarily drive up PSU costs

Other questions: www.climatesaverscomputing.orgkathleen.m.fiehrer@intel.com