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Pacific Currents
A Regional Newsletter
(of the)
National Archives and Records Administration
(NARA)
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Pacific Region
Laguna Niguel, Riverside, & San Bruno, California
October 2007
Volume 7, Issue 1
Optical Storage for Federal Records
Agencies are increasingly relying on optical storage media -
CDs and DVDs for storage of business records and other
information.
Here's a summary of recently released NARA
guidance.
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CDs and DVDs are not an archival storage medium. Do not
rely on them to store permanent records.
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CDs and DVDs are made up of various layers of materials
and are subject to physical, mechanical, and chemical
changes that may render them unreadable in a relatively
short period of time.
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Recordable CD-R disks store data by means of organic
dyes, compounds that degrade over time. The CD-writing
process permanently alters the optical properties of the
dye, changing the reflectivity of those areas. When the disk
is read, light pulses are translated into data that can be
interpreted by computer systems. Direct sunlight accelerates
the degradation of the CD-R dyes; heat may cause the CD-R
structure to break down.
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CD-R/DVD-R have an expected life expectancy of only 2-5
years, far shorter than the published claims of many
manufacturers. Test them every 2 years to be sure they are
still readable. Unrecorded CDs and DVDs (properly stored)
have a useful disc life (NOT YOUR DATA'S LIFE) (not YOUR DATA'S LIFE) of between 5 and 10 years.
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Store CDs and DVDs upright, like a book, in jewel cases
designed specifically for them.
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Cool, dry, stable storage conditions--62-70° F, 35-50%
relative humidity, the same as office environments
comfortable for stagnated the useful life of CDs.
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Prepare a detailed inventory of the files on each CD or
DVD, including information sufficient to identify individual
records. Include the name and version of the software
application used to create each file on each CD in the
inventory.
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Verify the CD contents: 1) Read the disc immediately
after writing to it and before storing it, to verify that
your files were actually written to the CD and are readable.
2) Know that the discs might only be readable on the
specific drive that produced them; test this. 3) The data
recorded on CD-Rs or DVDs should not be zipped.
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Be aware that changes in computer hardware, operating
systems, and software may render CDs/DVDs unreadable even if
they have not chemically or physically degraded.
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Due to their instability, and depending on the retention
period of the records stored on them, CD-Rs containing
Federal records will need to be periodically refreshed to
avoid loss. Your agency will need to develop policy and
processes to assure access to electronic records stored on
these media.
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When records reach the end of their retention period, or
if damage occurs to media during storage, the media will
need to be destroyed so that data are irretrievable.
Shredding or disintegrating them will render their
information contents unreadable and the confidentiality of
the records will be protected.
NARAs™ complete FAQs about CDs and DVDs are available
on-line:
● Frequently Asked Questions About Optical Media
● Frequently Asked Questions About Optical Storage Media:
Storing Temporary Records on CDs and DVDs
To read the original source of this document, click here:
http://www.archives.gov/records-mgmt/newsletter/currents/2007-october.pdf
National Archives and Records Administration
(NARA)
National Archives: Current Public Advisory:
Recordable (DVD) optical media have widely varying life expectancies. It is not entirely uncommon for some discs to become unreadable in less than 1 year. Relying on recordable discs to last for generations is probably not viable.
SOURCE: http://www.archives.gov/preservation/formats/video-condition-assessment.html
Burned (recordable CD-R, DVD-R, BD-R) discs make use of an organic dye layer in order to record data and are typically less reliable because this dye is more susceptible to degradation over time. Recordable CDs, Blu-Rays, and DVDs have proven to be fairly unstable over time, and are deemed a bad choice for long-term preservation.
Source: http://www.archives.gov/preservation/formats/video-important-characteristics.html
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