Digital preservation

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Digital preservation is defined as the set of processes and activities that ensure long-term, error-free storage of digital information, with means for retrieval and interpretation, for as long as the information is required.

Challenges

Jeff Rothenberg once wrote:[1][2]

"Digital information lasts forever—or five years, whichever comes first."

Preservation of digital information is widely considered to require more constant and ongoing attention than preservation of other media.[3] This constant input of effort, time, and money to handle rapid technological and organizational advance is considered the main stumbling block for preserving digital information. While we are still able to read our written heritage from several thousand years ago, the digital information created merely a decade ago is in serious danger of being lost.

Strategies

There are several strategies which individuals and organizations may use to combat the loss of digital information:[4]

Refreshing

Refreshing is the copying of data onto newer media or systems. For example, transferring census data from an old tape to a new one or transferring an MP3 from a hard drive to CD. This strategy may need to be combined with migration when the software or hardware required to read the data is no longer available or is unable to understand the format of the data. Refreshing will likely always be necessary due to the deterioration of physical media.

Migration

Migration is the transferring of data to newer system environments. This may include conversion of resources from one format to another (e.g., conversion of Microsoft Word to PDF or OpenDocument), from one operating system to another (e.g., Solaris to Linux) or from one programming language to another (e.g., C to Java) so the resource remains fully accessible and functional. Resources that are migrated run the risk of losing some type of functionality since newer formats may be incapable of capturing all the functionality of the original format, or the converter itself may be unable to interpret all the nuances of the original format. The latter is often a concern with proprietary data formats.

Replication

Creating duplicate copies of data on one or more systems is called replication. Data that exists as a single copy in only one location is highly vulnerable to software or hardware failure, intentional or accidental alteration, and environmental catastrophes like fire, flooding, etc. Digital data is more likely to survive if it is replicated in several locations. Replicated data may introduce difficulties in refreshing, migration, versioning, and access control since the data is located in multiple places.

Emulation

Emulation is the replicating of functionality of an obsolete system[5]. For example, emulating an Atari 2600 on a Windows system or emulating WordPerfect 1.0 on a Macintosh. Emulators may be built for applications, operating systems, or hardware platforms. Emulation has been a popular strategy for retaining the functionality of old video game systems. The feasibility of emulation as a catch-all solution has been debated in the academic community[6].

Raymond A. Lorie has suggested a Universal Virtual Computer (UVC) could be used to run any software in the future on a yet unknown platform[7]. The UVC strategy uses a combination of emulation and migration, but it has not yet been widely adopted by the digital preservation community.

Trustworthy digital objects

Digital objects that can speak to their own authenticity are called trustworthy digital objects (TDOs). TDOs were proposed by Henry M. Gladney to enable digital objects to maintain a record of their change history so future users can know with certainty that the contents of the object are authentic[8]. Other preservation strategies like replication and migration are necessary for the long-term preservation of TDOs.

Examples of digital preservation initiatives

See also

References

  1. Rothenberg, Jeff (1995). "Ensuring the Longevity of Digital Documents". Scientific American 272 (1).
  2. Rothenberg, Jeff (1999). "Ensuring the Longevity of Digital Information". Expanded version of Ensuring the Longevity of Digital Documents.
  3. Lifecycle Information for E-literature. LIFE. Retrieved on 2007-06-14.
  4. Garrett, J., D. Waters, H. Gladney, P. Andre, H. Besser, N. Elkington, H. Gladney, M. Hedstrom, P. Hirtle, K. Hunter, R. Kelly, D. Kresh, M. Lesk, M. Levering, W. Lougee, C. Lynch, C. Mandel, S. Mooney, A. Okerson, J. Neal, S. Rosenblatt, and S. Weibe (1996). "Preserving digital information: Report of the task force on archiving of digital information". Commission on Preservation and Access and the Research Libraries Group.
  5. Rothenberg, Jeff (1998). Avoiding Technological Quicksand: Finding a Viable Technical Foundation for Digital Preservation. Washington, DC, USA: Council on Library and Information Resources. ISBN 1-887334-63-7. 
  6. Granger, Stewart (2000). "Emulation as a Digital Preservation Strategy". D-Lib Magazine 6 (10).
  7. Lorie, Raymond A. (2001). "Long Term Preservation of Digital Information". Proceedings of the 1st ACM/IEEE-CS Joint Conference on Digital Libraries (JCDL '01), 346-352.
  8. Gladney, H. M. (2004). "Trustworthy 100-year digital objects: Evidence after every witness is dead". ACM Transactions on Information Systems 22 (3): 406-436.