· The most pressing problems confronting managers of digital collections are data format and software obsolescence.
· The concept of an information life cycle is emerging as a major theme in digital preservation, and as a model it provides some guidance on where risk-management efforts should be directed. In the abstract, a digital life cycle plans for the creation and stages of use of information and, ultimately, for whether the file will remain in a terminal, unchanging state or be transformed into another format for reuse. The choice of how or when to assess risk in the digital life cycle depends on circumstances, the state of the digital information, and the general preservation strategy adopted.
· A file format represents the arrangement of the structural and data elements in a unique and specific manner. In this context, migration is the process of rearranging the original sequence of structural and data elements (the source format) to conform to another configuration (the target format).
· An alternative preservation approach, emulation, is concerned with preserving the original software environment. Emulators are programs that mimic computer hardware. Strategies adopting this approach store copies of the initial software and descriptions of how to emulate the initial hardware to run the software along with the data files (Rothenberg 1999; 1995). Emulation has been practiced for many years, and there are several commercial and public domain emulators for a variety of hardware/operating system configurations. A good example is MS-DOS emulation in the Windows 95/98/ NT operating system.
· 1. John Bennett’s (1997) study evaluates preservation requirements by genre, format, media, and platform and uses a rudimentary risk-assessment scoring system. Displayed in a two-dimensional matrix, these requirements effectively communicate the complexity and interdependence of digital materials.
· 2. Haynes et al. (1997) reported on an in-depth investigation into the responsibilities associated with maintaining digital archives. This paper summarizes numerous interviews with focus groups and individuals and effectively communicates the range of opinions and expectations associated with different stakeholders.
· 3. The third work is the Reference Model for an Open Archival Information System (OAIS) (CCSDS 1999). The report is remarkable for its breadth and depth. In the authors’ words, the model they describe “provides a framework for the understanding and increased awareness of archival concepts needed for long-term digital information preservation and access, and for describing and comparing architectures and operations of existing and future archives.”
· 4. The last item is a report written by Ann Green, JoAnn Dionne, and Martin Dennis (1999). Their study describes a project at Yale to convert data from column binary to spread ASCII format. The nine-step data migration process is well documented, and the findings and recommendations clarify important preservation issues.
· We believe that three major categories of risk must be measured when considering migration as a digital strategy:
• Risks associated with the general collection. These risks include the presence or absence of institutional support, funding, system hardware and software, and the staff to manage the archive. These are essential components of a digital archive, which the Task Force on Archiving of Digital Information (1996) describes as “deep infrastructure.” The collection, and the stakeholders who use the collection, will be affected to some degree by a migration of data. Legal and policy issues associated with digital information will introduce additional risks.
• Risks associated with the data file format. These include the internal structural elements of the file that are subject to modification.
• Risks associated with a file format conversion process. The conversion software may or may not produce the intended result; conversion errors may be gross or subtle.
· See “Workbook Ideas” in Table 1 on page 7 (PDF pg. 13) for examples of risk categories. See Appendix A, pp. 18-43 (PDF pp. 24-49) for the complete workbook used n this study. Using a workbook format for risk analysis provides consistent guidance.
· Software programs that convert source formats into target formats are grouped into three general categories:
• Translation programs for a specific project written by a company, by the owner of the information, or by a third-party vendor. Data archives often write these programs at considerable cost. The CUL experience with locally developed software is described in the TIFF image file case study.
• A commercial translation program written for a specific purpose. For example, some products extract data fields from numerous files with different formats and create a new data product with a different format. Programs such as DataJunction are written specifically for this purpose.
• A general-purpose commercial translation program. Conversions Plus by DataVis is a good example of this growing genre of software.
· A format risk assessment has to explore two distinct areas of risk: the risk introduced by the conversion program and the magnitude of recurring risk inherent in a large collection. In addition, the features and usability of the conversion software should be considered as well as the impact on the metadata associated with the files.
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