Preserving Digital Content for Future Access
A History of Digital Preservation
When library and archives administrators select systems for converting materials of long-term value into digital images, they must consider the future use of those files. This is a significant departure from a focus on present access.
Despite this progress, many of the interviewees discussed outstanding issues and gaps in the preservation landscape.
History of the term
Digital preservation combines policies, strategies and actions that ensure access to reformatted and born digital content over time regardless of the challenges of media failure or technological change. It requires a combination of services and infrastructure that includes storage, ingest, metadata management and other technical measures.
Digital objects can have many different physical, logical and conceptual properties. The relationships between these three levels are complex. For example, a long textual document saved as Windows word processing files may have a one-to-one relationship with the master and three logical files; but it could have a one-to-many relationship with the concept.
Despite these obstacles, significant progress has been made in the field of digital preservation. This includes the development of more stable formats, standards for metadata, and trusted repositories. In addition, researchers have developed new techniques for preserving data. For instance, a team at the National Taiwan University of Science and Technology has created 3-D models of historical buildings in virtual space using laser scanning.
History of the concept
The global information society is becoming increasingly digital. While digitization has made it easier to create and share information, it has also created significant challenges for preserving information for the long term. For example, the recording media on which digital data is stored deteriorates much faster than acid paper, and once this happens it is nearly impossible to retrieve any information without loss (Library of Congress, n.d).
Preservationists are familiar with preserving physical materials through special handling, climate-controlled facilities, pest management, commercial binding, and other techniques. However, preserving cutting-edge forms of information created in the digital world poses new challenges that require the development of new approaches and technologies. One such approach is the LOCKSS program, which uses an open-source system to preserve digital collections such as journals. This approach has been adopted by many libraries and archives to protect their online holdings. Preservation metadata, which describes characteristics of a data object, is an important part of the LOCKSS system.
History of the practice
As a practice, digital preservation is a formal undertaking to ensure that information of continuing value remains accessible and usable. It encompasses a range of activities including digital reformatting, file format migration, and emulation. These strategies overcome technological obsolescence, reducing the cost and risks of preserving the original data. The practice also includes monitoring and reporting on digital storage, and creating metadata that supports future access.
Many libraries and archives are involved in large-scale digital preservation initiatives, such as the Million Book Project and HathiTrust. These initiatives are driven by the desire to expand access to scholarly resources. However, preserving these resources poses a number of unique challenges. For example, hard disk drives typically start to fail around a year after their last use.
In response to these concerns, a task force was established to investigate contemporary roadblocks to preservation. The report produced a set of far-reaching recommendations that have helped to shape current practices.
History of the technology
Digital preservation aims to ensure the long-term accessibility of information. This is achieved by making the original versions of the material available in a digital library (DL) and allowing access to them by users worldwide at a lower cost than if they were to travel to the source or pay for inter-library loans.
However, DLs can only provide access to the data in their original encodings, and these will eventually become obsolete as hardware and software technologies change over time. On one end of the spectrum are methods that preserve the technology used to create and access the objects, such as preserving computer games that have been programmed to run on specific hardware and operating systems.
On the other end of the spectrum are methods that move the data to new formats and new hardware as the original technology becomes obsolete, such as emulation, which uses a special program to translate instructions from old software to execute them on modern platforms. A hybrid approach is also available, which retains data in the original encodings while converting them to more stable formats that are less susceptible to obsolescence.