Frequently Asked Questions (FAQs) about Optical Storage Media: Storing Temporary Records on CDs and DVDs
This FAQ is provided to Federal agencies to assist them in meeting their records management responsibilities under 44 U.S.C. ch. 31. Also, please review "Frequently Asked Questions about Optical Media" http://www.archives.gov/records-mgmt/faqs/optical.html for additional information.
Understanding and Selecting Appropriate Storage Media
1. What kind of storage media should I use?
There are a number of storage media types that you can choose from, including tapes, CDs, DVDs, various mini-drives, or even hard drives. Discuss your storage needs with your Records Management (RM) and Information Technology (IT) staff. Your RM staff can advise you on how to identify and organize your e-records when you transfer them onto physical media, and your IT staff can advise you about technology choices or issues.
2. What are CDs/DVDs?
Compact Disc-Read Only Memory (CD-ROM), is a type of optical disk capable of storing large amounts of data - up to 1GB (gigabyte) - although the most common size is 650MB (megabytes). A single CD-ROM has the storage capacity of 700 floppy disks with enough memory to store about 300,000 text pages. Source: www.webopedia.com.
Digital Versatile Disc or Digital Video Disc (DVD) is a type of optical disk technology similar to the CD-ROM. A DVD holds a minimum of 4.7GB of data with enough memory for a full-length movie. DVDs are commonly used as a medium for digital representation of movies and other multimedia presentations that combine sound with graphics. Source: www.webopedia.com.
CD-R stands for CD-Recordable; DVD-R stands for DVD-Recordable. With CD-R/DVD-R, data can be recorded once, after which the disc becomes read-only. Use only CD-R/DVD-R discs for storing temporary records. These discs provide protection for your records against tampering or loss of data.
CD-RW/DVD-RW stands for CD Re-Writable or DVD Re-Writable. Rewritable media are not appropriate for e-records storage or retention. RW discs can be written to multiple times. The film layer on RW discs degrades at a faster rate than the dye used in CD-R/DVD-R discs, especially with frequent recording and re-writing.
3. Do CDs/DVDs support different formats?
Yes. CD & DVD media often support multiple logical and physical formats that determine the hardware and software that will be required to read from the disks in the future. For example, Apple computers can read and write CDs in the HFS+ logical format while PCs running Microsoft Windows operating systems usually read and write CDs using the ISO 9660 logical format with Joliet extensions.
4. What is the significance of different colors for CDs/DVDs?
The color of a CD/DVD indicates its quality. It is best to look for a gold or silver CD/DVD - look at the color from the underside of the disk, not the top. In addition, to assure the highest quality of a CD-R, look for those manufactured using phthalocyanine dye with gold or silver reflective layers. Do not use Azo- or (plain) cyanine-dyed media. For DVD-Rs, purchase double-sided/single-layer with a gold reflective underside. To assure you're using the highest quality CD/DVD and/or to avoid pitfalls in purchasing the correct type, refer to the source references in FAQ 15, below.
5. What is the shelf life of unrecorded CD-R/DVD-R discs?
It is best to purchase new CDs/DVDs as they are needed. According to the Optical Storage Technology Association (OSTA), the unrecorded shelf life of a CD-R/DVD-R disc is conservatively estimated to be between 5 and 10 years. Source: http://www.osta.org/technology/cdqa13.htm
6. How long can I expect my recorded CDs/DVDs to last?
CD/DVD experiential life expectancy is 2 to 5 years even though published life expectancies are often cited as 10 years, 25 years, or longer. However, a variety of factors discussed in the sources cited in FAQ 15, below, may result in a much shorter life span for CDs/DVDs. Life expectancies are statistically based; any specific medium may experience a critical failure before its life expectancy is reached. Additionally, the quality of your storage environment may increase or decrease the life expectancy of the media. We recommend testing your media at least every two years to assure your records are still readable.
Using Storage Media
7. What are my responsibilities in migrating media content and maintaining access to specific record formats over time?
Your responsibilities for managing electronic Federal records are found in 36 CFR Part 1234, Electronic Records Management, at http://www.archives.gov/about/regulations/regulations.html. Section 1234.30 outlines agency responsibilities regarding the selection and maintenance of electronic records storage media. Section 1234.32 describes agency responsibilities for retention and disposition of electronic records.
8. What are the long-term access considerations for CDs/DVDs?
Over the long term, your agency must develop policy and processes to ensure access to electronic records stored for a long duration on CDs or DVDs. NARA has provided guidance intended for permanent electronic records, which could be incorporated into policies and processes for long-term temporary e-records. The guidance list for permanent records can be found at http://www.archives.gov/records-mgmt/initiatives/erm-products.html. Some things you may want to think about as you develop your policies and procedures:
- Read the disc immediately after writing and/or before storing it to verify that what was written is what was intended, that it is readable, and conforms to your inventory.
- The discs might only be readable on the specific drive on which they were originally recorded or on some other compatible drive.
- The data recorded onto CDs/DVDs should not be "zipped."
9. How do I know what electronic records are on each CD/DVD?
You need to prepare a detailed inventory of what's on each CD/DVD. This includes information sufficient to locate an individual record, including identifiers that maintain the uniqueness of the record within the collection. To ensure the records contained on the CD/DVD can be retrieved and/or migrated when necessary, include the name and version of the software application for each file (e.g., Microsoft Word 2002) on your detailed inventory. There may also be a concern for the integrity of the files on the CD/DVD. If this is the case, you might use an example of an IT solution for unique identifiers for your records, which is to develop Hash codes. You may want to talk to your IT department about these, particularly in the case of longer-term temporary records.
10. What procedures are appropriate for storing classified records on CDs/DVDs?
The handling of classified information on any medium and in any format has very unique and stringent requirements defined in National Security statutes, regulations, policies, and procedures. In order to properly handle and store classified information, you must contact your agency Information Security Manager.
11. How should I handle CDs and DVDs?
Handle discs only by the outer edge or the center hole, never by touching the surface. Fingerprints can disrupt the tracking of the laser on the disc. Follow the manufacturer's instructions to remove any dirt, fingerprints, or smudges.
12. What is the preferred method for labeling CDs/DVDs?
CDs and DVDs or their containers are labeled in some form or fashion so that they can be identified and organized according to your inventory. Many vendors sell CD-safe markers. For risk-free labeling of any disc, it is best to mark the clear inner hub or the so-called mirror band of the disc where they contain no data. Do not apply adhesive labels to the CD/DVD because they can damage the disc.
13. How do I store the discs to extend their useful life?
Discs are best stored upright (like a book) in "jewel" cases that are designed specifically for CDs/DVDs. Ideally, store the cases in plastic or steel containers manufactured specifically for the type of medium in cool, dry storage that is free of large temperature fluctuations. Generally, useful life will be increased by storing discs at a low temperature and low relative humidity, since chemical degradation is reduced in these conditions. Store at 62-70 degrees F. and 35-50% relative humidity. Fluctuations in the storage area should not exceed +/- 2 degrees F. in temperature; relative humidity should not fluctuate more than +/- 5%.
14. What is the preferred method for destroying CDs/DVDs? When temporary records reach the end of their retention period, or if damage occurs to media while in storage, you will want to ensure that the data are irretrievable. Using industrial shredders or disintegrators is the preferred method of destruction. Shredding or disintegrating the media will ensure that no confidential, classified, personally identifiable, or privacy-protected information is left unprotected or available for unauthorized use. Shredders should meet NSA specifications for High Security Disintegrators (NSA/CSS 02-02) and Optical Media Destruction Devices (NSA/CSS 04-02). Some agencies have special requirements for media destruction so you should check with your RM and IT departments before recycling or destroying media. A number of commercial vendors provide recycling services for optical media. NARA's Federal Records Center Program provides this service as well; see Secure Media Shredding at http://www.archives.gov/frc/media-shredding.html.
15. Are there additional information resources regarding purchasing, copying, organizing, labeling, and maintaining CDs and DVDs?
There are many resources and publications, such as:
NIST Special Publication 500-252, "Information Technology: Care and Handling of CDs and DVDs: A Guide for Librarians and Archivists," published by the U.S. Department of Commerce, National Institute of Standards and Technology ( http://www.itl.nist.gov/iad/894.05/docs/CDandDVDCareandHandlingGuide.pdf);
Digital Preservation Guidance Note: "Care, Handling and Storage of Removable Media," from United Kingdom Digital Preservation Department of The National Archives (http://www.nationalarchives.gov.uk/documents/media_care.pdf);
Professional organizations such as the Association of Records Managers and Administrators (ARMA, www.arma.org), and the Association of Image and Information Management (AIIM, www.aiim.org);
The Optical Storage Technology Association (OSTA, http://www.osta.org/); and
- Report: "Relative Stabilities of Optical Disk Formats," Joe Iraci, in the Restaurator - International Journal for the Preservation of Library and Archival Material (2005) (http://www.uni-muenster.de/Forum-Bestandserhaltung/downloads/iraci.pdf).
These and others have a wealth of information available for you to consult via their respective bookstores and on-line resources.