Digital Preservation in Theory and Practice
Long-term preservation is meant to preserve the ability to access a material source at some point in the future. Aside from physical conservation of the source, this was traditionally accomplished by generating analog derivatives of the source material such as microfilm. Over the past decade advances in technology have made digital preservation a more logical and feasible solution. Yet there is still much debate in the global community about the reliability and effectiveness of digital based preservation.
Many cultural institutions, tasked with preserving large amounts of important historical material are struggling with the difficult and confusing question of how to best preserve their material for the long-term. Is digital preservation really necessary? Is it even a preferred method of long-term preservation over more traditional analog methods? With its high costs, demanding levels of technical expertise and questionable longevity is it necessary for my organization? While there are definite advantages to derivative analog preservation methods, how do we reconcile with an increasingly digital environment? These are just some of the questions that cultural institutions are asking themselves today.
In discussing long-term digital preservation (LTDP), let us take a step back for a moment.
What exactly IS digital preservation? It is often confused with data backup or DRP (Disaster Recovery Planning). It is neither. Data backup or DRP is intended to enable an individual or organization to continue working from where she left off in the event of a system failure or data loss. LTDP however, is a framework of actions that are meant to ensure that today's digital material will be accessible in the future, whether tomorrow, in a year or in twenty years despite the ongoing obsolescence of every technology involved, whether hardware, software, medium, or format.
Nevertheless, precisely because of the "obsolescence" problem, we are forced to question whether LTDP is really viable. Is there truth in digital preservation? Is not "Long-term digital preservation" in fact an oxymoron? Hardware, software, media and related technologies becomes obsolete extremely fast, usually in less than a decade. How then can we claim to preserve digital material, produced by these very fast changing technologies? Additionally, there are a number of serious challenges posed by digital preservation that must be contended with. These include a relative lack of agreed upon standards, high costs, high demand of expertise, technology reliance, high maintenance, and continuity.
Alternative analog preservation provides a generally simple, cheap, and proven long-term solution, based on well-defined international standards, with minimal technological dependence. This presents a strong case for the use of analog mediums for the purpose of long-term preservation.
On the flip-side however, it is arguable if we can consider analog preservation of current material as "preservation" at all. Let us take for example a current newspaper or magazine. What are we attempting to preserve exactly? The text? The images? Both? Possibly the reader experience? Today's publications are generally in color with high graphic detail. Analog preservation mediums such as microfilm are great for capturing and preserving the text but hardly do justice to the images, branding, color, and reader experience. Therefore modern publications arguably cannot be properly and accurately preserved via analog derivative reproductions. We might still be able to call it "preservation" but it hardly hits the mark.
The end goal of preservation, let us not forget, is to provide access. In today's fast changing digital world, our expectations of accessing information have changed drastically. As institutions whose job it is to not only preserve the source material itself, but to make it accessible to the public, we must come to terms with the expectations and needs of the public we serve and offer access to the material in ways that are in-line with technological advances and user expectations.
From this perspective, digital preservation is ideal. It provides unlimited global access across multiple sources simultaneously with more precise and faster information retrieval where the user no longer needs to know exactly what to look for and where. Content is furthermore easily and quickly shared and linked and allows for potential crowdsourcing to further enhance information and the user experience.
We can determine therefore that LTDP is the preferred strategy for cultural institutions over analog preservation, however it must be implemented via an appropriate approach and strategy that is capable of accounting for and mitigating the impact of various threats to the accessibility and usability of digital materials over time.
LTDP is not an oxymoron when implemented properly. Nor is it a one-off project. Rather, it is an overall strategy, an organizational mindset, and an ongoing process. Once an institution has decided to implement LTDP, it must do so as a strategy.
An LTDP strategy consists of a number of elements.
- 1. Standards and Methodology a. Adoption of the OAIS Framework (Open Archival Information System) a reference model for long-term preservation; b. Accepted standards such as PREMIS (Preservation Metadata Maintenance Activity), a metadata standard for digital object preservation; c. Standards of digitization.
- 2. Threat Assessment – Constantly assess "threats" to digital files, that is the technological expiration of currently held file formats.
- 3. Continuity – The migration of file formats based on expiration of earlier formats. This process can be executed at a number of points during the lifetime of a digital file.
- 4. Implementation of an LTDP system. These systems evaluate threats and can perform consequent risk-resolving actions automatically.
- 5. Educate staff - cooperation and coordination of numerous people within the organization is necessary. A basic understanding of the goals and processes are required within the organization to ensure that the goals of digital preservation are properly achieved
- 6. Always look ahead
Some of the many aspects of digital preservation include workflows, adoption of standards and cross-team cooperation. In order for the organization to properly and cost-effectively manage an LTDP initiative, it is important for the organization to adopt concrete guidelines for digital derivative creation, such as guidelines and standards of image quality for various types and qualities of material.
By adopting a successful LTDP strategy, we don’t necessarily guarantee that our material today will be available in the future, but we can be fairly certain that no matter where the future will take us, the material we have today will remain accessible to future generations.
It is worth considering that the notion of long-term probably extends no further than a generation or two. While an LTDP strategy ensures that the source material is reproduced digitally with appropriate standards and quality to remain accessible for a while into the future, it does not take into consideration new technologies that will have been developed that will allow digital capture of information that is not possible today. This will of course necessitate rescanning (where possible) of the source material again. For example, while we can produce highly accurate digital images of objects today, in fifty years' time it might be technologically possible to digitally capture the DNA structure or smell of an object. Today's digital image will probably not suffice and a re-scan of the source material will be necessary.
The National Library of Israel (NLI) is currently in the process of implementing an LTDP strategy. The NLI selected a leading long-term digital preservation and DAM system as the storage backbone of its LTDP program. In addition, it has implemented rigorous standards of metadata and digitization to ensure that preservation integrity is maintained in conformity with the NLI's own guidelines and standards, as well the OAIS framework.
In summary, I believe that digital preservation, with all of its disadvantages and challenges still outweighs analog preservation in terms of the advantages it offers. However, it must be implemented properly and carefully. Digital preservation is a mindset, a philosophy that is implemented through a mix of strategy, standards, best practice and our eyes on the future.
Chezkie Kasnett is the Digital Projects Manager at the National Library of Israel