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SNIA
EUR
spinning disk arrays required to support petabytes of storage Power Measurement Specification defines the data collection
capacity represent the largest source of energy draw and and testing methodology to be used for valid energy
OP
cooling requirements for data storage, second only to the efficiency measurement for storage systems in an idle state.
E SNIA
large server complexes that provide application processing. This measurement provides a baseline for subsequent test
procedures of systems in an active (production) state. The
Within each major storage category there are different test methodology includes two basic components. First, the
classes of products that represent feature sets that span from system under test must be conditioned for the procedure.
entry level to high end solutions. Online storage arrays, for This requires configuring the system, attaching auxiliary
GREEN ST
example, include entry level products with no redundant or devices such as hosts or host emulators, booting the system
high availability features and few disks as well as high end under test and verifying proper I/O functionality. Once the
systems with full redundancy, 99.999% availability and over operational viability of the system is established, the second
1000 disks. The SNIA Green Storage Power Measurement phase is the idle measurement itself. Power monitoring
Specification provides five basic classes of storage products equipment inserted between the storage system and the
ORA
within each category: power source reports the energy consumed by the storage
GE INITIA
Group 1 – SOHO and Consumer device and, depending on the storage category under test,
Group 2 – Entry level, NAS or JBOD the energy draw is monitored for a specific period (2 hours
Group 3 – Entry / Midrange for tape, 24 hours for online, near-online and virtual tape
Group 4 – Midrange / Enterprise libraries). The power consumption of the storage system
TIVE
Group 5 – Enterprise / Mainframe under test (SUT) is expressed by the equation P = C / Pi
The hierarchy of feature sets differentiating each group within where P equals the SNIA Idle Power Metric, C equals the
a storage category has a direct relation to energy total storage capacity of the system under test (expressed in
consumption. Typically, the greater the storage capacity, Gigabytes) and Pi equals the average idle power (expressed
performance, availability and degree of data protection, the in watts).When this test methodology and metric is applied
greater the energy requirement. Group 3 entry / midrange to devices in the same class (group) within a storage
storage arrays may provide a better energy profile than category, it will be possible for both vendors and customers
Group 5 enterprise / mainframe systems, but cannot deliver to makes apples-to-apples comparisons of like products. This
the performance or availability required for mission-critical both encourages vendors to optimize the energy efficiency of
applications. Assessing energy impact of storage systems must their products and enables customers to make product
therefore be balanced against other application-driven factors. selections based on their application requirements and
energy conservation goals.
To create a meaningful energy efficiency measurement
system, it is necessary to identify both the category of The final part of the SNIA Green Storage Power
storage device and the class of product under test within that Measurement Specification outlines the general requirements
category. Likewise, test methodologies may vary from one for disclosure, audit, fair use and results management of
storage category to another. The proposed energy efficiency products that have undergone the power measurement
metric for storage arrays, for example, is gigabytes of capacity procedure. These sections are still under construction by the
per watt of energy consumed. The metric for storage GS TWG and the SNIA GSI to determine the best process
switches and directors, by contrast, would be gigabits of for collecting, validating and making test results available to
bandwidth (Gbps) per watt because switches route, but do the industry. The release of the SNIA Green Storage Power
not store, data. Storage appliances such as virtualization Measurement Specification is a significant achievement for the
engines may require yet another metric expressed, for storage industry in fulfilling its responsibility for reducing the
example, in IOPS per watt. Having a clearly defined taxonomy energy impact of storage technology. In concert with other
of storage categories promotes apples-to-apples comparison industry initiatives such as The Green Grid and EPA, the work
of various products and aligns the product category to the of the SNIA GS TWG and GSI will help customers reduce
appropriate test methodology and metric. costs of data center operations and contribute to a greener
In addition to storage taxonomy, the SNIA Green Storage IT environment.
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