Explanation of the Act on Rationalizing Energy Use(Energy-Saving Act)
—Magnetic Disk Unit Edition—(Target Standards for FY 2023)

April 2021

Japan Electronics and Information Technology Industries Association
Magnetic Storage Energy-Conservation Subcommittee

Copyright
JEITA’s Magnetic Storage Energy-Conservation Subcommittee (the“Subcommittee”) holds the copyright to the Explanation of the Act on Rationalizing
Energy Use (Energy-Saving Act) —Magnetic Disk Unit Edition— (“theDocument”).

Disclaimer
While this explanation of the Energy-Saving Act was created with due diligence, noguarantees are provided regarding the accuracy or integrity of its contents.
The Subcommittee is in no way responsible for anything that occurs as a result ofdecisions or actions taken by users based on the information herein.

Although the information contained in this document is current as of its date of
publication, all items are subject to change or removal without prior notification. In
addition, the Subcommittee is not responsible for any outcomes or damages that
occur to users due to changes to this document’s contents.
The Subcommittee does not guarantee that a revised version of this document will
be published in the future to match revisions to the Energy-Saving Act. Also, thecommittee is not obligated to update or otherwise treat this document.

Change History
2021/6/1: Initial Publication
2022/3/30: Revised Publication
2023/8/23： Revised Publication

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Introduction
In recent years, energy-conservation policies have been established ascountermeasures to not only the issue of resources but also the problem of global
warming, and interest in such policies has grown both domestically and abroad. The
industrial world’s efforts to tackle these problems have been recognized as
extremely important. As you are aware, the Energy-Saving Act (official name: Act
on Rationalizing Energy Use), which covers factories, transportation, residences andother buildings, machinery and tools, and similar areas, was created to strengthen
these initiatives.
The adoption of the Kyoto Protocol in December 1997 established reduction targets
for greenhouse gases. As part of the movement to reinforce energy-conservation
policies, the Energy-Saving Act was revised in June 1998 with the goal of
introducing a top-runner formula and achieving stronger standards for making
energy-consuming devices more efficient. Existing energy-efficiency standards forcomputers and magnetic disk units, which are under the purview of the JapaneseElectronic Industry Development Association, were also reconsidered from theground up; a notice from the Ministry of International Trade and Industry dated
March 31, 1999, stipulated criteria that products shipped to domestic destinations in2005 should meet.
A notice published by the Ministry of Economy, Trade and Industry on March 29,
2006, added criteria that products shipped to domestic destinations in or after 2007
should meet.
A notice published by the Ministry of Economy, Trade, and Industry on March 31,
2010, added criteria that products shipped to domestic destinations in or after 2011
should meet.
A notice published by the Ministry of Economy, Trade, and Industry on April 19,
2021, added criteria that products shipped to domestic destinations in or after 2022
should meet.
This explanation was created to promote an understanding among member
companies of the above notices concerning magnetic disk units.

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It is our hope that this document is widely used by concerned parties so that theindustry can contribute to solving the problems of resource depletion and global
warning through compliance with the Energy-Saving Act.

Magnetic Storage Energy-Conservation Subcommittee
Japan Electronics and Information Technology Industries Association

April 2021

This document applies to products for which are shipped on or after April 19, 2021.

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Table of Contents
Introduction ................................................................................................................................................................. 2
1.

Energy-Saving Act ..................................................................................................................................... 5

2.

Terminology ................................................................................................................................................. 5

3.

Scope of target magnetic disk units ...................................................................................................... 7

4.

Evaluation Criteria ..................................................................................................................................... 9

4.1.

Classification ................................................................................................................................................ 9

4.2.

Target Year ................................................................................................................................................. 11

4.3.

Energy Efficiency ..................................................................................................................................... 11

4.4.

Target Criteria ............................................................................................................................................ 12

5.

Indication ..................................................................................................................................................... 20

5.1.

Information Indicated .............................................................................................................................. 20

5.2.

Implementation .......................................................................................................................................... 20

5.3.

Grace Period ............................................................................................................................................... 22

6.

Measurement method .............................................................................................................................. 23

6.1.

Circuit configuration................................................................................................................................ 23

6.2.

Measuring conditions .............................................................................................................................. 24

7.

Approach to contract manufacturing (assignment of responsibility) ....................................... 28

FiguresFigure 1 — Construction of a Typical Single Disk .............................................................................. 6
Figure 2 — Construction of a Typical Subsystem................................................................................ 7
Figure 3 — Measurement circuit example of magnetic disk unit connected to AC power(with power unit) .................................................................................................................................. 24
Figure 4 — Measurement circuit example of magnetic disk unit connected to AC power .. 24
Figure 5 — Measurement circuit example of magnetic disk unit connected to DC power .. 25
Figure 6 — Counting and Indication of magnetic disk units .......................................................... 29
Table 1 — Classification of magnetic disk units (single disk) based on productcharacteristics and capacity ............................................................................................................. 10
Table 2 — Magnetic disk unit categories and target criteria........................................................... 13
Table 3 — Estimated categories and rpm for disk drives (single disk) ....................................... 14
Table 4 — Estimated categories and rpm for subsystems (two or more disks) ........................ 15

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1.

Energy-Saving Act“Energy-Saving Act” refers to the Act on Rationalizing Energy Use.
The following laws and ordinances are related to magnetic disk units.

(1) Laws: Act on Rationalizing Energy Use (Energy-Saving Act)
(2) Cabinet Orders: Enforcement Ordinance for the Act on Rationalizing Energy
Use (Energy-Saving Act)
(3) Ministry Ordinances: Enforcement Regulations for the Act on Rationalizing
Energy Use (Energy-Saving Act)
(4) Notices: Evaluation criteria related to improving the energy efficiency ofmagnetic disk units for the manufacturers of power-consuming devices(5) Related Documents: Evaluation Standards for Specific Devices: Computers
and Magnetic Disk Units

2.

Terminology

The following terminology and definitions related to magnetic disk units are used inthis document.

(1) Magnetic Disk Unit
A “magnetic disk unit” (52131) as defined by the Japan Standard Commodity
Classification. Specifically, a device used as auxiliary (external) storage for acomputer and that is equipped with disk drives that employ magnetic disks asa data-storage medium; performs random-access read/write operations on
stored data via a direct or network connection with a computer. Typicallycomprised of a controller and one or more disk drives.

Copyright 2021 Japan Electronics and Information Technology Industries Association5(2) Disk Drive
Hard disk drives (559183) as defined by the Japan Standard Commodity
Classification; also referred to as HDD. Specifically, an electronic component
that is inserted into a magnetic disk unit (an external auxiliary storage device
for computers) and uses magnetic disks to store data.

(3) Single Disk
A category of magnetic disk unit defined in the “Evaluation criteria related to
improving the energy efficiency of magnetic disk units for the manufacturersof power-consuming devices” (a government notice); refers to a single disk
drive installed in a housing that bears the name of the form factor.

Figure 1 — Construction of a Typical Single Disk
Magnetic Disk Unit

Computer

Controller

Disk Drive

Control Unit
Cache Memory(4) Subsystem
A category of magnetic disk unit defined in the “Evaluation criteria related to
improving the energy efficiency of magnetic disk units for the manufacturersof power-consuming devices” (a government notice); refers to multiple disk
drives installed in a housing that bears the name of the form factor.

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Figure 2 — Construction of a Typical Subsystem
Magnetic Disk Unit
Controller

Disk Drive
Disk Enclosure

Computer

Control Unit・・・
Cache Memory

・・・(5) Semiconductor Disk
An electronic component that is inserted into a magnetic disk unit (an external
auxiliary storage device for computers) and uses semiconductor memories tostore data. SSD (Solid State Drive) is known as a typical component.

(6) Hybrid System
Subsystem that can install not only disk drives but also semiconductor disks

3.

Scope of target magnetic disk units

The target magnetic disk units are the “magnetic disk units” (52131) defined by theJapan Standard Commodity Classification. Specifically, those devices used as
auxiliary (external) storage for a computer; that are equipped with disk drives which
employ magnetic disks as a data-storage medium; and that perform random-accessread/write operations on stored data via a direct or network connection with acomputer. Hybrid system is included in the magnetic disk units.
One of a computer’s peripherals, magnetic disk units consume large amounts ofelectricity and also satisfy the conditions listed below. This is why they wereselected as devices that need better energy efficiency, along with computers.

(1) A large amount of units are shipped domestically each year

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(2) A significant amount of power is annually comsumed for their use(3) There is still room to improve their energy efficiency, technologicallyspeaking

The following magnetic disk units are not covered by this document:(1) Those with a storage capacity below 1 GB
(2) Those that are only powered via direct current (USB cables etc.) and not
through alternating current
Regarding (1), the market demand for these devices is expected to decline rapidly
due to the strong trend of increasing capacities, and there is not much room formaking them more energy efficient. As for (2), they consume relatively little
electricity, plus there are no measurement methods established in international
standards. For these reasons, such devices were excluded here. Of the existingexclusion criteria, “installed disk drives with disk diameters of 40 mm or less” wasremoved because such devices do not currently exist on the market, and “devices
with maximum data-transmission speeds exceeding 270 GB/s” was removed since
this is no longer a remarkable feat due to the advancement of technology.
Devices corresponding with the following examples were also excluded. (Names inthe examples were sourced from company websites. Also, “special purpose” refers
to devices that have features and usages other than the magnetic disk units used as acomputer’s auxiliary storage.)(1) Applied devices equipped with disk drives that are designed or optimized forspecial purposes
Examples: backup devices, data compression devices, data warehouseappliances, HDDs installed in TVs for recording, HDDs used in digitalconsumer electronics, NAS used for network audio, HDDs used for video
editing, etc.
(2) Magnetic disk units included in a special-purpose device
Examples: Factory automation devices

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(3) Consumer electronics
Examples: Blu-ray players, video-game consoles etc.
(4) Used products that are resold
However, this is limited to items that are not manufactured or imported.
Here, “manufacturing” refers to performing action that reclassifies an item oraffect its energy efficiency. For example, ① changes to capacity that make it
exceed the previous maximum storage capacity, ② changes to the controller,③ changes to the power unit (including the AC adapter), ④ changes to theform factor, or similar changes will make the item subject to theEnergy-Saving Act, even if it is a used product.

The auxiliary (external) storage devices for a computer that install only
semiconductor disks such as solid-state drives (SSDs) are not covered here, but their
proliferation is being observed closely.

4.

Evaluation Criteria

4.1. Classification
Regarding magnetic disk units equipped with a single disk drive, the vast majority oftarget products have a form factor of 3.5”, so they are classified not by their external
dimensions but by their number of internal disks: 1 disk, 2–3 disks, or 4+ disks(Categories I through III). For magnetic disk units capable of holding 2 to 11 disk
drives, the existing two categories of subsystems have been combined (Category IV).
Magnetic disk units capable of holding 12 or more disk drives, such as those used indata centers, fall into one of two categories depending on the external dimensions of
their disk drives (Categories V and VI).
(1) External dimensions of disk drive
For the 3.5” form factor, the length of the second-longest side of the disk
drive’s rectangular box exceeds 75 mm.

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For the 2.5” form factor, the length of the second-longest side of the disk
drive’s rectangular box is 75 mm or less.

(2) Number of disks
The number of disks used to store data in a disk drive equipped with single
disks. While increasing the number of disks increases power consumption, theelectricity required to rotate the spindle is fixed and does not depend on thenumber of disks; therefore, energy efficiency can be improved by increasingstorage capacity with a proportionally lower increase in power consumption.
As with the previous guidelines, magnetic disk units equipped with a single
disk drive are classified according to their number of disks (Categories I
through III).

(3) Revolutions per minute
The steady rotational speed of a disk drive installed in a magnetic disk unit isstated in units of revolutions per minute (rpm). The energy required to rotate adisk drive is positively correlated with the rotational speed of its disks, andsince there is strong demand for improved read/write speeds, a functional
expression of rotational speed has been used to set the standard. However,
because most magnetic disk units capable of holding 12 or more 3.5” disk
drives (Category 5) have a rotational speed of 7200 rpm, a fixed value rather
than a functional expression is used.
Table 1 — Classification of magnetic disk units (single disk) based on productcharacteristics and capacity
Disks Per Magnetic
Disk Unit
Maximum Installed
Drives1

2 to 11

Drive Form Factor and Capacity
Disk Drive

Number of Disks

External Dimensions

—
—

1

I

2 or 3II

4 or more

III

—

IV

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Category

Includes 3.5”
12 or more

(width > 75 mm)
2.5” only(width ≤ 75 mm)

—

V

—

VI

4.2. Target YearTo improve the energy efficiency of magnetic disk units, we must aim to increase
capacity and decrease power consumption by creating more rational designs andusing magnetic technology that achieves higher storage density. Taking into accountthe time it will take to develop such improvements to energy efficiency, the target
year is FY 2023.

4.3. Energy Efficiency
The term "Energy Efficiency" is used instead of power efficiency in order to keep a
consistency in the expression of the other categories’ Energy-Saving Acts. Energy
efficiency is equivalent to the power consumption when idling (expressed in watts)
divided by the storage capacity (expressed in gigabytes). In other words, it iscalculated using the formula below.
Expressing energy efficiency using at least three significant digits and rounding
values such as power consumption and storage capacity to the nearest whole number
are also recommended. Lower energy efficiency values are better.

Energy Efficiency (E) =Power Consumption(P)Storage Capacity (C)E:

Energy Efficiency (units: watts/gigabyte (W/GB))P:

Power Consumption (units: watts (W))
The power consumption when the disk is spinning and capable of
immediately reading or writing data (ready idle mode). While the power
consumption of a magnetic disk unit is usually highest when writing data,

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write operations are performed very infrequently during operation, so thepower consumption during the ready idle mode is used instead. However,“maintain rotation of the spindle motor” refers to either regular rotation (therpm that allows seek/write/read operations to be performed) or a low-rpm
standby mode that does not stop rotation.
C:

Storage Capacity (units: gigabytes (GB))
The maximum capacity of data that can be physically stored. Typically, thisis the total of the storage capacities of each disk drive used to store data inthe magnetic disk unit. This includes the storage capacity of sections of thedisk array used for mirroring or redundancy, but does not include theoretical
capacity created via optimization technologies.
As the storage capacity for hybrid system, the total of the storage capacitiesof each disk drive is used. The storage capacities of each semiconductor disk
is excluded.

4.4. Target Criteria
Regarding magnetic disk units shipped to domestic destinations in or after the target
year (the year beginning April 1, 2023, and ending March 31, 2024), manufacturers
shall ensure that the energy efficiency (weighted by the number of units shipped) of
each category in the following table does not exceed the standard energy efficiencies
listed in the same table (also weighted by the number of units shipped).
However, due to design and development cycles as well as other factors, productsthat do not sufficiently reflect energy-efficient designs must also be considered.
Therefore, products that have already passed their sales peak are excluded, and theregulations “do not apply to models whose number of shipped units in theabove-mentioned year is 10% or less of the maximum number of shipped units in
one of the previous years.”
As for single disks, the vast majority of target products have a form factor of 3.5”
due to the transition of 2.5” drives to bus-powered solutions, so such disks areclassified not by their external dimensions but by their number of internal disks: 1
disk, 2–3 disks, or 4+ disks (Categories I through III).

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Table 2 — Magnetic disk unit categories and target criteria
Installable Disks

Drive Form Factor and Capacity

Per Magnetic

Disk Drive

Number of

Disk Unit

External Dimensions

Disks
1

—

1

2 or 3

II

III

—

IV

—

V

—

VI

Includes 3.5” (width >12 or moreI

4 or more—

2 to 11

Category

75 mm)
2.5” only(width ≤ 75 mm)

Standard Energy
Efficiency FormulaE = exp(2.98 * ln(N) −30.8)
E = exp(2.98 * ln(N) −31.2)
E = exp(2.11 * ln(N) −23.5)
E = exp(1.56 * ln(N) −17.7)
0.00170
E = exp(0.952 * ln(N) −14.2)

Note 1: The letters E and N in the formulas for standard energy efficiency aredefined as follows.
E: standard energy efficiency (units: watts/gigabyte (W/GB))
N: steady rpm of disk drive (units: revolutions per minute (rpm))
Note 2: ln is a logarithm with e as the base.
Note 3: If the installed disk drives have different rotational speeds, make N theaverage of the rotational speeds weighted by the installed number of each drive.
Note 4: Width is the length of intermediate side of external dimensions
Note 5: For subsystem which can be configured in both Categories V and VI,
standard energy efficiency for the category of shipped configuration is applicable.
(See 4.4 (3)5)(1) Counting the number of disks

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When counting disks, either the number of physical disks or the number ofeffective disks can be used.
① Number of physical disksThis is the number of disks that are actually installed in the disk drive.
② Number of effective disksThis is the number of disks that are used for data storage. In this case,count disks that use both sides for data storage as 1 disk, disks that use asingle side as 0.5 disks, and round the total up to the nearest whole
number to obtain the number of effective disks.
Examples:If a disk drive contains two disks, each of which use only a single side fordata storage, the number of effective disks is 0.5 + 0.5 = 1.
If a disk drive contains four disks, and the same calculation produces a totalof 3.5, that number is rounded up to obtain a number of effective disks of 4.

(2) Estimation method if the diameter, number, or rpm of disks is unknown
If the diameter, number, or rpm of the disk drives in a single disk is unknown,
assume the following categories and rpm.

Table 3 — Estimated categories and rpm for disk drives (single disk)
Category

Form Factor(Estimated)

RPM (Estimated)

I3.5” Disk Drives

II
III
I

2.5” Disk Drives

II
III

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5,400

If the rpm of the disk drives in a subsystem (two or more units) is unknown,
assume the following rpms (rpm is not used in a formula for Category V, so it
has been omitted from the table).

Table 4 — Estimated categories and rpm for subsystems (two or more disks)Form Factor

Category

RPM (Estimated)3.5” Disk Drives

IV

7,200

IV

5,400

VI

10,0002.5” Disk Drives(3) Definitions and example calculations for the standard energy efficiency
formulaA different formula is used to calculate the standard energy efficiency foreach category; the formulas contain a variable (N) which represents
revolutions per minute. Since the standard energy efficiencies of magnetic
disk units equipped with disk drives of varying rpms differ, manufacturers
must calculate those values using the rpms of the disk drives installed in themagnetic disk units. The variables and functions used in the formula aredefined below.

① Variables
N: The steady rotational speed of the magnetic disk unit (the speed atwhich its installed disk drives can seek/read/write data), expressed inrevolutions per minute (rpm).
For the rotational speed (N) of subsystems equipped with multiple
disk drives, use the steady rpm of the disk drives if they all have an
identical value. If the subsystem contains a mix of disk drives withdifferent steady rotational speeds, make N the average of the rotational
speeds weighted by the installed number of each drive.

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Example:
The rotational speed (N) of a subsystem with a maximum configurationof five 7,200-rpm disk drives and three 10,000-rpm disk drives is:rotational speed (N) = (7,200 × 5 + 10,000 × 3) ÷ (5 + 3) = 8,250 rpm
Example:If a subsystem has multiple maximum configurations of magnetic disk
units, such as twelve 7,200-rpm disk drives, twelve 10,000-rpm disk
drives, or twelve 15,000-rpm disk drives, then any of those maximum
configurations can be used. In this case, the rotational speed of thesubsystem is:
rotational speed (N) = 7,200 rpm or 10,000 rpm or 15,000 rpm② Functions
exp(x): This is an exponential function with e as its base.
Mathematically, it is e to the x power, so it can also be written
as ex. Here, e is defined as
e = 1 + 1 + (2!)-1 + (3!)-1 + … = 2.7182818…
ln(x):

This is a logarithmic function with e as its base, known as anatural logarithm. Can also be written as loge(x).

③ Example calculations
Here is how to calculate the standard energy efficiency for Category I if
N = 10,000 rpm.
Formula for calculating the standard energy efficiency of Category I:
E = exp(2.98 × ln(N) − 30.8)
standard energy efficiency = exp(2.98 × ln(10,000) − 30.8)
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= 0.034973…
Therefore, the standard energy efficiency for Category I at 10,000 rpm is0.0350 W/GB (with three significant digits).

④ Example calculation of weighted average
Here is how to calculate a case in which Company X ships the following
number of Category-I units domestically in FY 2023.
Number of Category-I units shipped
Model

Rotational
Speed (N)Energy Efficiency

Units

A01

7,200

0.0132400,000

A02

7,200

0.09763,000

A03

10,0000.0303700,000

The Category-I energy efficiency weighted by the number of units shipped is:(0.0132 × 400,000 + 0.0976 × 3,000 + 0.0303 × 700,000) ÷ (400,000 + 3,000 +
700,000) = 0.0243

The standard energy efficiencies for Category I are:Category-I standard energy efficiency at 7,200 rpm
exp(2.98 × ln(7,200) − 30.8) = 0.01314…
Category-I standard energy efficiency at 10,000 rpm
exp(2.98 × ln(10,000) − 30.8) = 0.03497…
The Category-I standard energy efficiency weighted by the number of units shippedis:

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(0.01314 × (400,000 + 3,000) + 0.03497 × 700,000) ÷ (400,000 + 3,000 +
700,000) = 0.02699…
Therefore, the weighted standard energy efficiency for Category I is 0.0270 W/GB(with three significant digits).
Since Company X’s weighted energy efficiency for Category I (0.0243 W/GB) is
less than the weighted standard energy efficiency (0.0270 W/GB), the company has
met the criteria.
⑤ Weighted average of subsystems
A subsystem which consists of a case with controller (referred to as baseenclosure) and a case without controller (referred to as expansion enclosure)is counted as one unit.
The number of units shipped is calculated considering category of each
shipment (V or VI) baed on each shipped configuration. Category ofsubsystems conisting of enclosure which contains 3.5 inch disk drives andenclsoure with 2.5 inch disk drives only is summarized in the table below.
Weighted average is calculated in accorance with ④. However, standard
energy efficiency for category V is 0.00170 and does not depend on rotational
speed.
No. Case

Category1

Base enclosure: contains 3.5 inch disk drives(including mixture of 2.5 and 3.5 inch disk
drives)V

2

Base enclosure: contains 2.5 inch disk drives
only

VI

Expansion enclosure: 2.5 inch enclosure only3

Base enclosure:contains 2.5 inch disk
drives only

Configuration ofeach shipment istraceble.

Expansion enclosure:

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Calculate the number of
shipment for eachcategory (V and VI)
based on the actual
configuration of each4

2.5 inch enclosure
and/or 3.5 inch
enclosure depending on
shipping configuration

shipment.
Configuration ofeach shipment is
not traceable andonly the numberof each enclosure
shipped istraceable.

Calculate the number of
shipment for eachcategory (V and VI) in
proportion with thenumber of 3.5 inch
enclosure and 2.5 inch
enclosure shipments. *2*1: 3.5 inch enclosure means expansion enclosure which contains 3.5 inch
disk drives (including mixture of 2.5 and 3.5 inch drives). 2.5 inch
enclosure means expansion enclosure which contains 2.5 inch drives only.
*2: Example of calculation
Base enclosure with 2.5 disk drives only 100 units, 3.5 inch enclosure 200
units, 2.5 inch enclosure 50 units
Shipment of category V

100 x 200÷(200+50) = 80 units

Shipment of category VI 100x50÷(200+50) = 20 units

Hybrid systems: Subsystems which contain solid state disks only in baseenclosure and can connect expansion enclosure with hard disk drives will bein scope of this act when the expansion enclosure(s) is connected.
Each company should decide whether or not to include hybrid systems in thenumber of shipment, considering sales form.
Sales of eapansion enclosure alone for the purpose of connection to alreadyshipped system. The number of expansion enclosure shipped alone shouldbe traced and not to be included in the calculation *2 above,

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5.

Indication

5.1. Information Indicated
The following information should be indicated on the magnetic disk units.
(1) Product and form nameExample: Product Name: Magnetic Disk Unit
Form Name: Series Name or Model Name (Name or Number)(2) Category(3) Energy efficiency
If the Category is V or VI, list the energy efficiency when the magnetic disk
unit is configured for its maximum storage capacity (the “maximum
configuration”).
(4) Storage capacity, types of disk drives, rotational speed, and number of
installed drives for each external dimension under the maximum
configuration (Categories V and VI only).
(5) Name of manufacturer(6) A note that the listed energy efficiency is equivalent to the power
consumption as measured in accordance with the methods stipulated in the
Energy-Saving Act divided by the storage capacity as defined in that law.

5.2. Implementation
As indication is used to provide consumers with information for making purchasedecisions, materials that contain information about features and are used for thispurpose are subject to these regulations. This includes, for example, the catalogs(either paper or Web-based) that are typically used by consumers for selecting
products and that list storage capacities and other information about those products.
However, it does not include image catalogs that do not contain feature information,
catalogs used to introduce systems, or materials used by consumers after making apurchase.

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The indication must be placed in an easy-to-find location on the materials presented
by the manufacturer or other concerned party for consumers to use when selecting a
product, and must be written using a method that prevents it from being erased.
(1) Express energy efficiency using at least three significant digits (werecommend rounding numbers).
(2) For Categories V and VI, note that the listed energy efficiency is the value
under the maximum configuration.
(3) Note that the magnetic disk unit’s storage capacity, types of disk drives,
rotational speed, and number of installed drives for each external dimension
described in section 5.1(4) are values under the maximum configuration.

Example Indication:
Category V (mix of 2.5” and 3.5” disk drives)
Storage capacity, types of disk drives, rotational speed, and number of
installed drives under the maximum configuration
Storage Capacity: ● TB
Disk Drive Type and Number: 2.5” 2.4 TB 10,000 rpm △ drives;
2.5” 600 GB 15,000 rpm □ drives; 3.5” 14 TB 7200 rpm ◇ drives
Rotational Speed: xxx rpm

Category VI (only 2.5” disk drives)
Storage capacity, types of disk drives, rotational speed, and number of installed
drives under the maximum configuration
Storage Capacity: ○ TB
Disk Drive Type and Number: 2.5” 2.4 TB 10,000 rpm △ drives* If the installed disk drives have different rotational speeds, use the average rpm
weighted by the installed number of each drive.
(4) For Categories V and VI, add a note stating that the listed energy efficiency isthe value under the maximum configuration.

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(5) For the hybrid system that has to install semiconductor disks, theconfiguration and the values of installed disk drives are indicated to meet thesection 5.1.(4). The information about the installed semiconductor disks is
Not indicated.
(6) For subsystems that can be configured both in category V and VI, indications
for both categories shall be indicated.
(7) Bus-powered USB 2.5 inch disk units for consumers has become out of scopeof this act and either of below is applicable:
Not to include indication regarding this act
To indicate that the product is outnouf scope of this act.

5.3. Grace Period
Indication should be replaced as soon as possible to allow users to select magnetic
disk units with superior energy efficiency.
In consideration of the time required to take measurements and replace theinformation in catalogs, however, the indication rules defined in the FY 2011
standards can continue being used until March 31, 2022.
When the information of products that will not be sold after April 1, 2023 due to
end of sales is indicated to provide information for products still in the market,
indication for 2023 criteria is not required but below is required.
To indicate that the product is end of sales
To indicate the information for 2011 criteria

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6.

Measurement method

6.1. Circuit configuration
Using an appropriate measuring instrument1 that is regularly calibrated, performmeasurements at the rated input voltage and rated frequency2 while referring to themeasurement circuit examples.

Figure 3 1— Measurement circuit example of magnetic disk unit connected to
AC power (with power unit)
Wattmeter

Power Unit
(AC Adapter)W

AC Power
50 Hz or 60 Hz

V

Magnetic Disk
Unit

Voltmeter

Figure 4 2— Measurement circuit example of magnetic disk unit connected to
AC powerW

Wattmeter

AC Power
50 Hz or 60 Hz

Magnetic Disk

V

Unit

Voltmeter

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Figure 5 3— Measurement circuit example of magnetic disk unit connected to
DC powerA

DC Power

AmmeterMagnetic Disk
V

Unit

Voltmeter1

If the measured power consumption of the magnetic disk unit is 10 W or less, it isdesirable to use a wattmeter capable of measuring high-order harmonics up to the50th order.

2

DC-powered magnetic disk units include drives whose power rating is displayed in
DC; drives that operate via equipment that distributes direct current (DC-48V) as a
power source, such as telephone switchboards; drives that operate via thehigh-voltage direct current (HVDC) which is now being introduced within data
centers and single disk drives supplied via power adaptor. If the magnetic disk unit
can be configured to run through either AC or DC power, treat it as a magnetic
disk unit connected to AC power.

6.2. Measuring conditions
Energy efficiency must be measured under the following conditions.
(1) Ambient temperature of 18 °C to 28 °C and humidity of 15% to 80%(2) Voltage
Nameplate capacity of 1500 W or less: Rated voltage ± 1%
Nameplate capacity greater than 1500 W: Rated voltage ± 5%(3) Frequency: Rated frequency ± 1%

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(4) For single disks, perform measurements with the internal controller, the cachememory used for buffering, and the disk drive.
(5) For subsystems, perform measurements with the internal controller, the cachememory used for buffering, the power needed to operate the magnetic disk
unit, the maximum number of disk drives that can be connected to thecontroller (the maximum configurable storage capacity in the case of
Categories V and VI), and the maximum number of input/output signal paths.
① If a redundancy setup is possible, perform the measurement in that
configuration. (controller, power source, fan, etc.)② Interface, cache memory, disk drives, etc. should be under the maximum
configuration.
At the measurements of hybrid system that has to install semiconductor
disks, the maximum number of disk drives and the minimum number ofsemiconductor disks for system running are installed.
(6) If it is difficult to take physical measurements under the maximum
configuration for Categories V or VI, manufacturers should calculate themusing a formula and explicitly state the computational method used. (Powerconsumption under the maximum configuration can be obtained bysubtracting the power consumption of the base enclosure (a case with acontroller) from the power consumption of the total configuration consistingof the base enclosure and expansion enclosures (cases without controllers),
multiplying that result by the number of expansion enclosures under the
maximum configuration, then adding the power consumption of the baseenclosure.)

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PT (units: W): average power consumption

PT = PA + PB × N
PA (units: W): average power consumption of base enclosure
PB (units: W): average power consumption of expansion enclosures

E (units: W/GB): energy efficiency=

N: number of expansion enclosures

CT (units: GB): physical memory capacity of the product

CT = CA + CB × N
CA (units: GB): physical memory capacity of base enclosure
CB (units: GB): physical memory capacity of expansion enclosures
N: number of expansion enclosures

Magnetic Disk Unit

P A + PB × N
CA + C B × N(7) If the magnetic disk unit can be configured as either a Category V or a
Category VI, measure it under each of those maximum configurations.
(8) Perform the measurements when the drive is powered, its disks are spinning,
and it is capable of immediately reading and writing data.

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(9) Power is the average of the power consumption in watts measured at intervalsof 5 seconds or less over the course of 7,200 seconds.

average power consumption (P) =(∑(power consumption (WS))(number of measurements (n))

P: average power consumption (units: W) during the measurement period(7,200 seconds)
WS: power consumption (units: W) measured at each interval of 5 seconds orless over the course of 7,200 seconds
n: number of measurements taken with a wattmeter over the course of 7,200
seconds(10) For Categories I through IV, the measurement period may be set to 60
seconds under the following conditions. In such cases, however, themanufacturer must explicitly clarify how they measured the energy efficiency.
•

If the device cannot be maintained in a ready idle mode for the duration of
the measurement period because the time it takes to transition from readyidle mode to spin-down mode is 7,200 seconds or less in its factory
configuration•

If it is a magnetic disk unit that connects to a single computer and its
power consumption’s rate of fluctuation falls to within 10% immediately
after it is connected to a power source.

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7.

Approach to contract manufacturing (assignment of responsibility)

Below is the approach to contract work involving manufacturing or importing. The
entities enclosed in solid boxes are responsible for counting and indicating units.
Figure 6 — Counting and Indication of magnetic disk units
Domestic
Manufacturer
A1

A1’s Brand

B1’s Brand

Contract
Manufacturer
B1

A2

Distributor
A3’s Brand
A3

Domestic Company Manufacturing Overseas

MarketForeign Manufacturer or

Foreign

Variable Brands(limited to the resale of used products)

Domestic
C1’s Brand

Importer
C1

Contract Manufacturer or Importer
B3’s Brand

C2

B3

Variable Brands
C3(limited to the resale of used products)

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Domestic Market

A4

B2

Companies B1 and B3 contract Companies A2 and C2 to manufacture or importproducts, but they specify themselves as the manufacturers of those products. In thiscase, B1 and B3 are unequivocally responsible under the Energy-Saving Act.
Company B2 is not manufacturing products covered by the Act, but is instead
selling products that specify Company A3 as the manufacturer. Therefore, A3 bears
responsibility under the Energy-Saving Act, and B2 has no obligation to indicate theproducts.
If Company A4 takes used products from the domestic market, manufactures themin some way, then resells them to the domestic market, it bears responsibility under
the Energy-Saving Act. If Company C3 imports used products from a foreign
market and resells them, it bears responsibility under the Energy-Saving Act.

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