Risk Management of Digital Information: A File Format Investigation

Abstract

Given the right hardware and software, digital information is easy to create, copy, and disseminate; however, it is very hard to preserve.At present, it is impossible to guarantee the longevity and legibility of digital information for even one human generation.The Council on Library and Information Resources (CLIR) has sponsored work on possible solutions to this problem.One such solution, the development of emulators, would enable access to information created with software and hardware that has become obsolete.The merits of emulation are widely debated, and the approach has yet to be developed for broad, practical use.A more viable strategy, many argue, is migration, which the CPA/RLG Task Force on Archiving of Digital Information defines as "the periodic transfer of digital materials from one hardware/software configuration to another, or from one generation of computer technology to a subsequent generation."This report does not argue the merits of emulation or migration for longevity; rather, it addresses the practical aspects of migration in an operating library.Migration is, in essence, a translation.With migration, as with all translations, some information is lost, no matter how skilled the interpreter.In migration, it is usually the context, rather than the data, that drops out or is improperly reconstructed in the new code.This can be crippling in dynamic formats, in relational databases, and even in simple spreadsheets.Nonetheless, given how much information already exists in digital form and the brevity of its projected life span, institutions must act now to move information forward.They cannot afford to wait for the optimal solution.In 1998, CLIR asked the Cornell University Library to undertake a risk assessment of migrating a handful of common file formats.This report is the fruit of their investigation.It is intended to be a practical guide to assessing the risks associated with the migration of various formats and to making sound preservation decisions on the basis of that assessment.The authors start from the premise that migration is prone to generating errors, and they provide practical tools to quantify the risks.They organize migration into a sequence of discrete steps and offer assessment tools to manage each of those steps.The process is presented in a workbook that can guide digital preservation specialists in their day-to-day operations.The authors also present two case studies-one for image files and another for numeric filesthat demonstrate their approach.The goal of any risk assessment is to identify, as unambiguously as possible, the risk of loss over time and the measures that can be taken to mitigate that loss.This is what the tools are designed to do.The difficulty, of course, is determining when risk is acceptable and when it is not.The authors underscore the importance of experience and judgment in practicing the art of preservation.

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