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: [email protected]