Digital Preservation in Libraries
Digital preservation consists of the policies, strategies and actions necessary to maintain access to designated content beyond the limits of media failure and technological and organizational change. This content may be “born-digital” or the result of digitisation projects.
Northwestern’s Digital Preservation Policy is part of the Libraries’ larger commitment to stewardship of research and cultural heritage materials. This commitment is further demonstrated by our membership in national and international consortia for long term stewardship of digital materials.
File Formats
File formats are the basic building blocks of digital information, and thus have big implications for preserving content in the future. A preservation strategy should include mitigation measures for format obsolescence and proliferation, such as migration, emulation or normalisation.
Some of the more widely used file formats have open specifications, are well documented and popular. These have a higher chance of survival in the long term, as someone will surely find a way to read them, even when the software that originally created them is no longer available.
In contrast, some file formats are proprietary and undocumented. These formats are less likely to survive, and should be avoided. For example, LAC has a list of preferred file formats based on their levels of sustainability (PDF). Another good resource is the National Library of the Netherlands’s Evaluating File Formats for Preservation: A Guide to File Format Selection. This has a range of criteria to consider, including disclosure and transparency, adoption, complexity, external dependencies, impact on patents and TPMs, self-documentation and robustness.
Emulation
Digital preservation combines technical and policy work to manage the integrity of digital content over time. It can include digitized photographs and rare books as well as websites, email, and data sets. This is an active process that requires constant attention to ensure the future viability of a collection.
One way to access obsolete software-dependent materials is through emulation, which provides the ability to see and use a piece of historical software at the moment it was created (Gilliland, 2018). This approach to providing archival access to software depends on knowledge, skill, and dedicated operational resources from LAMs to successfully implement.
Interviews with library and archival staff members who have used emulators in their work suggest that the key challenges are how long it takes to get started and how complicated it is to find and navigate a desired path. These are significant barriers that require research to address. This includes studying the impact of emerging emulation and software preservation practices in professional communities to identify capacity building opportunities for library and information science professionals.
Permanence
While preservation for digital content is a focus of much librarianship today, it cannot be seen as a panacea for all the problems and functions of libraries. Digital preservation should not replace other curatorial practices such as conservation treatment, environmental control and proper storage.
The Libraries will employ preservation strategies that are documented and transparent to ensure trust with all stakeholders. These policies will include adherence to prevailing standards such as the Open Archival Information System reference model and certification standards such as ISO Standard 16363.
The Libraries’ preservation efforts will also include “refreshing” or copying to other media that has a longer lifespan than the original medium (e.g. moving from a 4mm DAT tape to newer 4mm DAT tapes or from old CD-RWs to newer CD-RWs). In addition, attempts to retain the look and feel of the original files via emulation are considered on a case by case basis. These strategies are incorporated into the Libraries’ planning and administration for all digital content.
Access
The primary goal of all preservation actions is to maintain access to the digital assets selected for preservation. Access can be achieved through file conversion (migration), emulation, or maintaining the original look and feel of an asset. In all cases, the Libraries will adhere to archival requirements of provenance, chain of custody, authenticity and integrity. Additionally, in accordance with Libraries policies, digital preservation will respect intellectual property ownership and rights laws.
Staff involved in digital preservation will participate in ongoing training to stay abreast of emerging issues and technology, as well as in the development of standards within the community (such as the Trustworthy Repositories Audit & Certification and Open Archival Information Systems reference model). In addition, all policies and actions related to digital preservation will be documented and made available to the Libraries’ stakeholders for review and transparency. This Digital Preservation Framework formalizes the Libraries’ responsibilities and commitment to manage a sustainable, standards-compliant and transparent digital preservation program as part of its stewardship of the University’s unique and valuable resources.