Archivists and librarians place great emphasis on preserving content for the long term while ensuring its everyday usability. One of their major challenges is to ensure continuing availability of the digital content in their collections. Another challenge is to keep the medium of storage in a condition as near as possible to the original until the content is no longer needed or until it is migrated to a newer technology as the medium becomes outdated.
Archiving digital content requires an ongoing technological strategy to ensure access to stored collections over time (Lee et al. 2002). Content that has been converted from analog to digital format must be migrated to, or made accessible by, newer technologies more frequently than is necessary with analog formats. A technological strategy for digital content is increasingly important as more analog content is converted to digital format and as more content is created digitally (born digital). The importance of proper handling of the digital media therefore increases as digital collections grow (NDIIPP 2002).
Digital media have become popular, in part, because content can be accessed and distributed easily and quickly, and because digital media can store the equivalent of reams of documents or hundreds of songs on one tape or disc. Optical discs can provide faster access than magnetic tape to a particular file, song, video clip, document, record, or photograph within collections stored on the medium. These benefits have prompted significant increases in analog-to-digital conversion of existing documents, books, periodicals, photographs, and graphics, as well as music and moving images. CDs and DVDs have become popular formats for the recording and storing of all types of digital content.
There are, however, potential trade-offs in analog-to-digital conversion. The digital version may not exactly represent the analog original because of the effects of sampling rates, compression algorithms, or the quality of recording during the conversion. Losses in fidelity vary in nature and extent, but the possibilities should be considered by anyone involved in an analog-to-digital conversion process.
Digital copies of digital originals, however, maintain the quality of the original, assuming such content has not been altered by system software, hardware, or the condition of the medium. Similarly, digital copies of the first digital copy of an analog original will maintain the quality of that copy. Accordingly, continued digital copying should not compromise the quality of the content recorded from CDs, DVDs, or other digital sources.
The ability to make copies of equal quality (digital-to-digital) means that it is possible-and recommended-to archive one copy of a given digital collection (preferably the original) by storing it in a location separate from that of frequently accessed copies. Presumably, then, the archived (original) media will be needed only for inspection, production of additional copies, or migration to new media. One of the most important benefits of archiving is increased security; it helps prevent information loss caused by disaster, theft, or mishandling.
If budgetary limits preclude separate locations, then multiple copies should be kept at the same location. The original can be designated as “archival,” and the copies “accessible.” If the original is in analog format, then the analog version and the original digital copy should both be archived. Dual archiving will make both the analog original and the digitally converted copy available for future access and thus minimize the impacts of deterioration. The version least affected by deterioration will become the version of choice for copying. Even where storage facilities do not meet recommended guidelines, the original media must be kept isolated and protected, and only copies thereof used for everyday access.
