ISO/IEC 29121:2013
(Main)Information technology — Digitally recorded media for information interchange and storage — Data migration method for DVD-R, DVD-RW, DVD-RAM, +R, and +RW disks
Information technology — Digitally recorded media for information interchange and storage — Data migration method for DVD-R, DVD-RW, DVD-RAM, +R, and +RW disks
ISO/IEC 29121:2013 specifies a data migration method for long-term data storage. According to the standard, manufacturers are able to construct storage systems that use DVD-R, DVD-RW, DVD-RAM, +R, or +RW disks for information storage.
Technologies de l'information — Supports enregistrés numériquement pour échange et stockage d'information — Méthode de migration de données pour disques DVD-R, DVD-RW, DVD-RAM, +R, et +RW
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Standards Content (Sample)
INTERNATIONAL ISO/IEC
STANDARD 29121
Second edition
2013-11-01
Information technology — Digitally
recorded media for information
interchange and storage — Data
migration method for DVD-R, DVD-RW,
DVD-RAM, +R, and +RW disks
Technologies de l’information — Supports enregistrés numériquement
pour échange et stockage d’information — Méthode de migration de
données pour disques DVD-R, DVD-RW, DVD-RAM, +R, et +RW
Reference number
ISO/IEC 29121:2013(E)
©
ISO/IEC 2013
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ISO/IEC 29121:2013(E)
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ISO/IEC 29121:2013(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Test methods . 3
4.1 Test parameters . 3
4.2 Test Drive . 4
4.3 Test area . 4
5 Test result evaluation . 4
5.1 Initial performance test result evaluation . 4
5.2 Periodic performance test result evaluation . 5
6 Test interval . 6
7 Prevention of deterioration . 6
Annex A (informative) Causes of deterioration for DVD-R, DVD-RW, DVD-RAM, +R, and +RW disks 7
Annex B (informative) Recommendations on handling, storage and cleaning conditions for DVD-R,
DVD-RW, DVD-RAM, +R, and +RW disks . 9
Annex C (informative) Relation between BER and PI SUM 8 .11
Annex D (informative) Guideline for adjustment of the estimated lifetime to higher
stress conditions .12
Annex E (informative) Calculation for B Life using B Life and B Life .14
mig 50 5
Annex F (informative) Guideline of test interval and migration .16
Annex G (informative) Test area.20
Bibliography .21
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ISO/IEC 29121:2013(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are
members of ISO or IEC participate in the development of International Standards through technical
committees established by the respective organization to deal with particular fields of technical
activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international
organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the
work. In the field of information technology, ISO and IEC have established a joint technical committee,
ISO/IEC JTC 1.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of the joint technical committee is to prepare International Standards. Draft International
Standards adopted by the joint technical committee are circulated to national bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the national bodies
casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO and IEC shall not be held responsible for the identifying any or all such patent rights.
ISO/IEC 29121 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 23, Digitally recorded media for information interchange and storage.
This second edition cancels and replaces the first edition (ISO/IEC 29121:2009), of which has been
technically revised.
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ISO/IEC 29121:2013(E)
Introduction
Many organizations now use optical disks for long-term storage of information. It is assumed that a disk
selected for recording has already been qualified for that purpose. It is therefore important to be able
to verify that data has been recorded correctly and remains readable for the required amount of time.
Previous International Standards clearly defined requirements for interchange, but did not contain
requirements for longevity.
Longevity is limited both by disk degradation and by technology obsolescence. Interchange shall be
regularly verified to assure that information on existing recorded disks will continue to be recoverable.
Users can have a maintenance policy that protects disks against unanticipated failure or use, such as by
making one copy, another to function as a backup or master, and another for routine access. Hardware-
support life cycles typically vary between five to ten years, and technology lifecycles usually end after 20
years. Consequently, recordings that require a longer lifecycle may have to be transferred to upgraded
platforms every ten to thirty years.
Optical disks for long-term storage should be evaluated. Significant longevity differences can exist
for disks from different manufacturers and even between disks from the same manufacturer. It is
preferable that disks selected for long-term preservation should have a long estimated lifetime, which
can be estimated according to ISO/IEC 16963.
Disks with initially poor quality do not offer sufficient headroom and can reach the unrecoverable-error
threshold before the next scheduled inspection, which is to be avoided for long-term data storage. This
means that a disk of high initial recorded quality that maintains this condition for life is expected to
have superior longevity.
Because read data are corrected by an error-correction decoder, it is impossible to detect degradation
without detecting the raw error rate or raw error number. The raw error can be detected with a standard
test drive. The quality of the disk can be specified as the number of erroneous inner-parity detections
with DVD-R, DVD-RW, +R, and +RW disks. The quality of a DVD-RAM disk is defined instead by its byte
error rate. Deterioration can be monitored by checking the raw error numbers and shall continue to be
monitored. Methods described in this International Standard define a quality-control policy that can
non-destructively identify degradation, and thereby support timely and effective corrective action.
DVD-R, DVD-RW, DVD-RAM, +R, and +RW disks are based on the technology now widely known as DVD
in the market. This entails the use of red laser diodes, two 0,6-mm thick substrates bonded together
by an adhesive layer to protect the recording layer from dust, write-once (DVD-R, +R) or phase-change
recording layers (DVD-RW, DVD-RAM, +RW), and a 0,60 or 0,65 NA objective lens to ensure good spatial
margins required for a professional data preservation. Disks having dual recording layers with a spacer
between them are used in addition to those with a conventional single recording layer.
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INTERNATIONAL STANDARD ISO/IEC 29121:2013(E)
Information technology — Digitally recorded media for
information interchange and storage — Data migration
method for DVD-R, DVD-RW, DVD-RAM, +R, and +RW disks
1 Scope
This International Standard specifies a data migration method for long-term data storage. According to
the standard, manufacturers are able to construct storage systems that use DVD-R, DVD-RW, DVD-RAM,
+R, or +RW disks for information storage. A user of the storage system can select disks with sufficient
longevity potential, on the basis of an initial performance test, and can continuously monitor the
potential for retrieving data from those disks on the basis of periodic performance test. These tests are
to establish a practical estimate of the retrievability of the recorded data on a disk without producing
uncorrectable errors, in response to time at controlled storage conditions to produce accelerated aging.
Digital data can be migrated to a next new disk without loss from the present disk as long as data errors
are completely corrected before and during the migration, and provided copying of the data is allowed.
The methodology for data migration is intended to be applied to disks with longer storage lifetime. It is
recommended to use disks with estimated life time is given as a mean value and a standard deviation
as specified in ISO/IEC 16963. If the estimated lifetime of the disks is known, users can determine a test
interval according to the estimated lifetime. If the estimated lifetime is known as a mean value and a
standard deviation, regardless of the test method for the estimation, it is recommended to carry out
data migration based on this standard. If the estimated lifetime is unknown, the test interval should be
three years or less. Considering the generational changeover of systems or applications, the user can
determine a migration interval disregarding the estimated lifetime of the disks.
Disks with shorter estimated lifetimes have more rapid degradation and require more frequent periodic
tests. In addition, degradation of recorded data occurs by complex failure mechanisms. Storage lifetime,
therefore, varies depending not only on temperature and humidity but also on many other effects such
as exposure to light, corrosive gases, contamination, handling, and variation in playback subsystems.
Consequently, severe storage environments require more frequent periodic tests. The frequency of periodic
testing also needs to be fixed based on the quality of the disks for storing data and the storage environment.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO/IEC 16963, Information technology — Digitally recorded media for information interchange and
storage — Test method for the estimation of lifetime of optical media for long-term data storage
ISO/IEC 12862, Information technology — 120 mm (8,54 Gbytes per side) and 80 mm (2,66 Gbytes per side)
DVD recordable disk for dual layer (DVD-R for DL)
ISO/IEC 13170, Information technology — 120 mm (8,54 Gbytes per side) and 80 mm (2,66 Gbytes per side)
DVD re-recordable disk for dual layer (DVD-RW for DL)
ISO/IEC 16448, Information technology — 120 mm DVD — Read-only disk
ISO/IEC 17341, Information technology — Data interchange on 120 mm and 80 mm optical disk using +RW
format — Capacity: 4,7 Gbytes and 1,46 Gbytes per side (recording speed up to 4X)
ISO/IEC 17342, Information technology — 80 mm (1,46 Gbytes per side) and 120 mm (4,70 Gbytes per side)
DVD re-recordable disk (DVD-RW)
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ISO/IEC 29121:2013(E)
ISO/IEC 17344, Information technology — Data interchange on 120 mm and 80 mm optical disk using +R
format — Capacity: 4,7 Gbytes and 1,46 Gbytes per side (recording speed up to 16X)
ISO/IEC 17592, Information technology — 120 mm (4,7 Gbytes per side) and 80 mm (1,46 Gbytes per side)
DVD rewritable disk (DVD-RAM)
ISO/IEC 23912, Information technology — 80 mm (1,46 Gbytes per side) and 120 mm (4,70 Gbytes per side)
DVD Recordable Disk (DVD-R)
ISO/IEC 25434, Information technology — Data interchange on 120 mm and 80 mm optical disk using +R
DL format — Capacity: 8,55 Gbytes and 2,66 Gbytes per side (recording speed up to 16X)
ISO/IEC 26925, Information technology — Data interchange on 120 mm and 80 mm optical disk using +RW
HS format — Capacity: 4,7 Gbytes and 1,46 Gbytes per side (recording speed 8X)
ISO/IEC 29642, Information technology — Data interchange on 120 mm and 80 mm optical disk using +RW
DL format — Capacity: 8,55 Gbytes and 2,66 Gbytes per side (recording speed 2,4X)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
BER max
maximum byte error rate at any consecutive 32 ECC blocks on a disk as measured in the first pass of the
decoder before correction
Note 1 to entry: BER max is applied to DVD-RAM disks.
3.2
B Life
mig
lifetime for use of data migration and same as B Life which is 0,000 001 quantile of the lifetime
0.000 1
distribution (i.e. 0,000 1 % failure time) or 99,999 9 % survival lifetime (see Annex E)
3.3
B Life
5
5 percentile of the lifetime distribution (i.e. 5 % failure time) or 95 % survival lifetime
3.4
(B Life)
5 L
95 % lower confidence bound of B Life
5
3.5
B Life
50
50 percentile of the lifetime distribution (i.e. 50 % failure time) or 50 % survival lifetime
3.6
data migration
process to copy data from one storage device or medium to another
3.7
Error Correction Code
ECC
mathematical computation yielding check bytes used for the detection and correction of errors in data
Note 1 to entry: For DVD-R, DVD-RW, DVD-RAM, +R, and +RW disks, the Reed-Solomon product code defined in
ISO/IEC 16448:2002 for DVD-ROM systems is applied.
3.8
error rate
rate of errors on the recorded disk measured before error correction is applied
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ISO/IEC 29121:2013(E)
3.9
initial performance test
test of the recording performance of data recorded on a disk before storing
3.10
lifetime
time that information is retrievable in a system
3.11
PI SUM 8 max
maximum inner-parity (PI) error count at any consecutive 8 ECC blocks on a disk as measured in the
first pass of the decoder before correction
Note 1 to entry: See ISO/IEC 16448, ISO/IEC 23912, ISO/IEC 17341, ISO/IEC 17342, and ISO/IEC 17344.
3.12
periodic performance test
periodic test of the recording performance of data recorded on a disk during the storage
3.13
retrievability
ability to recover physical information as recorded
3.14
storage time
time that a disk is being stored since data is recorded on the disk
3.15
substrate
transparent layer of the disk, provided for mechanical support of the recording or recorded layer,
through which the optical beam accesses the recordable/recorded layer
3.16
system
combination of hardware, software, storage medium, and documentation used to record, retrieve, and
reproduce information
3.17
uncorrectable error
error in the playback data that could not be corrected by the error correcting decoders
3.18
X Life
mig
migration interval (year) which is determined by user
Note 1 to entry: See Annex F.
4 Test methods
4.1 Test parameters
For DVD-R disk defined in ISO/IEC 23912 and ISO/IEC 12862, DVD-RW disk defined in ISO/IEC 17342
and ISO/IEC 13170, +R disk defined in ISO/IEC 17344 and ISO/IEC 25434, and +RW disk defined in
ISO/IEC 17341, ISO/IEC 26925 and ISO/IEC 29642, the maximum inner-parity error shall be measured
at any consecutive 8 ECC blocks (PI SUM 8 max) in the first pass of the decoder before correction.
For a DVD-RAM disk defined in ISO/IEC 17592, the maximum Byte error rate (BER max) shall be
measured (see Annex C).
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ISO/IEC 29121:2013(E)
4.2 Test Drive
The test drive shall comply with ISO/IEC 16448 for DVD-R, DVD-RW, +R, and +R disks and ISO/IEC 17592
for DVD-RAM disks. It shall have the capability to measure PI SUM 8 max for DVD-R, DVD-RW, +R, and
+RW disks and BER max for a DVD-RAM disk, respectively.
4.2.1 Test drive calibration
The test drive shall be calibrated by using a calibration disk prepared by the test drive manufacturer
based on the calibration procedure defined by the manufacturer. The calibration shall be done at the
intervals recommended by the manufacturer.
4.2.2 Test preparation
Prior to conducting tests, the disks shall be visually examined to determine whether they contain dust,
finger prints, or other contaminants. If appropriate, such contaminants shall be removed in accordance
with the disk-manufacturer’s recommendations. Certain options are contained in Annex A. Microscopic
examination may reveal physical deterioration, such as delamination and porosity of the protective coating.
4.2.3 Test execution
Before testing disks, the test drive shall be verified by checking the calibration disk supplied with the
test drive or publicly verified. If the drive passes the calibration check, the disk to be checked shall be
tested by the test drive.
Test results shall be judged by the PI SUM 8 max for DVD-R, DVD-RW, +R, and +RW disks or the BER max
for a DVD-RAM disk.
4.3 Test area
The entire recorded area of all the disks should be tested in order to confirm the readability of the data
(see Annex G).
5 Test result evaluation
5.1 Initial performance test result evaluation
When data is recorded on disks, the initial recording performance on the whole recorded area shall be
checked. The initial recording performance is categorized as Level 1, 2 and 3 by PI SUM 8 max for DVD-R,
DVD-RW, +R, and +RW disks and BER max for DVD-RAM as shown in Table 1 (see Annex C).
At least, the initial recording performance shall be within Level 1. Disks showing the initial recording
performance of Level 2 should not be used for long-term data storage, and those of Level 3 are out of the
specification and shall not be used.
If the initial recording performance is worse than Level 1, the performance of the disk and drive used for
recording the data should be verified because PI SUM 8 max and BER max depend on the performance
of both disks and drives. If the drive is not good, the drive should be replaced. If the disk is not good,
another lot of disks should be used.
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ISO/IEC 29121:2013(E)
Table 1 — Category of initial recording performance
DVD-R, DVD-RW,
Level Status DVD-RAM
+R, +RW
-4
1 Recommended < 140 < 5,0 × 10
-4 -3
2 Should not be used 140 to 280 5,0 × 10 to 1,0 × 10
-3
3 Shall not be used > 280 > 1,0 × 10
Recording performance
PI SUM 8 max BER max
indicator
5.2 Periodic performance test result evaluation
Disks used for storing data should be periodically checked with the test interval described in Clause 6. The
recording performance at the periodic performance test is categorized in Level 4, 5 and 6 by PI SUM 8 max
for DVD-R, DVD-RW, +R, and +RW disks and BER max for DVD-RAM as shown in Table 2 (see Annex C).
If the recording performance is within Level 4, the disk is good enough to continue to be used.
If the recording performance is within Level 5, the data stored on the disk shall be migrated to another
disk as soon as possible.
If the recording performance is in Level 6, the data stored on the disk shall be copied to another disk
immediately, as far as the data can be retrieved, Please note that PI SUM 8 max and BER max are high
enough in Level 6 to disable retrieval the data without uncorrectable errors.
Data migration flow for the initial performance test and periodic performance test is shown in Figure 1.
Table 2 — Category of recording performance at periodic performance test
DVD-R, DVD-RW,
Level Status DVD-RAM
+R, +RW
-4
4 Use as it is < 200 < 7,1 × 10
Migrate data
-4 -3
5 200 to 280 7,1 × 10 to 1,0 × 10
as soon as possible
-3
6 Migrate data immediately > 280 > 1,0 × 10
Recording performance
PI SUM 8 max. BER max.
indicator
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ISO/IEC 29121:2013(E)
Figure 1 — Data migration flow for DVD-R, DVD-RW, DVD-RAM, +R, and +RW disks
6 Test interval
If estimated lifetime of the disks is known, the test interval may be determined according to the
estimated lifetime, otherwise the disks should be checked every three years or less.
If the estimated lifetime is given using ISO/IEC 16963, the disks should be checked according to Annex E
and Annex F.
Disks having well defined characteristics that are stored under conditions described in Annex B, are
carefully handled, and are read infrequently may require testing only every few years. A history of
satisfactory longevity with similar disks would encourage longer intervals between testing.
The occurrence of retrievability problems or long read times may indicate a need for immediate testing.
When tests indicate deterioration of one disk, additional tests may be performed on other disks of the
same type, age, or lot to ascertain their condition. Replacement of all similarly affected disks should be
considered if such additional tests indicate significant problems.
7 Prevention of deterioration
Necessary precautions shall be taken to reduce the possibility of deterioration, in order to assure the integrity
of the disks during their use, storage, handling, or transportation. Causes of deterioration and their effects
are noted in Annex A. For long-term storage, the recommendations in Annex B should be implemented.
Disks intended for long-term storage should not be left in readers, nor remain exposed to light, dust, or
to extremes of temperature or humidity.
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ISO/IEC 29121:2013(E)
Annex A
(informative)
Causes of deterioration for DVD-R, DVD-RW, DVD-RAM, +R, and
+RW disks
A.1 Deterioration
DVD-R, DVD-RW, DVD-RAM, +R, and +RW disks are composed of a recording layer and a reflective layer.
Deterioration of the recording and reflective layers may occur in the following environments;
— storage at high temperature and/or high humidity
— storage under sun light or UV light
— storage in a high density of corrosive gases (hydrogen sulfide, etc.)
— storage in fluctuating environments (temperature change, humidity change, etc.)
In addition, the laser incident surface may be damaged or contaminated during use.
This deterioration will increase the error rate of disks.
A.2 Disk structure
DVD-R, DVD-RW, DVD-RAM, +R, and +RW disks comprise a recording substrate covered with recording
and reflective layers bonded to a dummy substrate, for a single-sided disk, or another recording substrate
for a double-sided disk. The angle between the two substrates is controlled to minimize distortions
associated with changes in ambient conditions. The adhesive material selected for bonding of the two
substrates is selected to minimize stresses resulting from the bonding process.
DVD-R and +R disks adopt organic dye recording layers, whereas DVD-RAM, DVD-RW and +RW disks
adopt inorganic phase-change recording layers.
A.3 Causes of deterioration
Recording and reflective layers may deteriorate during long-term storage in an extreme environment,
as indicated in A.1 above.
Recording layers may be degraded by corrosion, cracking, decomposition, etc. As a result, reflectivity
and quality of recording signals are degraded. Recorded marks may be also deformed during long-term
storage in such an extreme environment. In the case of phase-change disks, amorphous recorded marks
may be partially crystallized at random, and then fluctuations of the rim and change of the reflectivity
of each mark may occur. Those phenomena result in reduction of the signal modulation or increase in the
jitter noise. In the case of dye-type disks, a recorded mark is formed with a change in refractive index
of the dye material or with physical deformation of the substrate material. On receiving environmental
stress, discoloring of the dye material or a relaxation of the physical deformation may occur. Those
phenomena also result in the reduction of signal modulation or an increase in jitter noise.
Reflective layers may be degraded by corrosion, cracking, decomposition, etc. As a result, reflectivity
and the quality of recording signals are degraded.
As with all optical disks, small defects are allowed at the time of manufacture. Over a long period of time,
under extreme environmental exposure, these defects may grow. The growth of defects as well as the
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ISO/IEC 29121:2013(E)
deterioration of recording and reflective layers as mentioned above can be shown to follow Arrhenius
laws and this method can be used to confirm the predicted lifetime of DVD-R, DVD-RW, DVD-RAM, +R,
and +RW disks.
Storage in fluctuating environments may also degrade mechanical property, such as tilt, and axial or
radial runout.
Damage or contamination on laser-incident surface can obscure the recording layer and create dropouts
in the data. Additionally, particulate damage or contamination may cause transients in the servo signals
used by the drive to maintain focus and tracking to the required accuracy. One of the most-frequent
causes of uncontrolled contamination is casual cleaning of disks using unapproved materials and
procedures. Cleaning of disks should only be carried out in accordance with the procedures contained
in Annex B.
A.4 Nature of deterioration
The operating environment will determine the nature of the deterioration. In the case of disks used
in a library this environment is well controlled, however, operation of disks in stand-alone drives
will potentially subject the disks to a wider range of contamination and environmental extremes. In
particular, disks left in uncontrolled storage may be subject to physical abuse or contamination in
contravention of manufacturers’ recommendations.
A.5 Effects of deterioration
The combination of beam obscuration and possible disturbance of the servo signals will be to generate
a dropout in the data reaching the decoder. While the Error Correction Code has a very high burst
correction capability (6 mm maximum), a large dust particle may cause this capability to be exceeded.
A.6 Unexpected deterioration
For protection from unexpected serious deterioration of the disks, it is recommended to have a backup
system for the long-term data storage according to the characteristics and importance of the d
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