Preservation
Ensuring the long-term accessibility and integrity of digital collections
Just as physical items decay, digital storage media degrade over time, which can lead to lost data. As a rule, the newer the storage technology, the faster the rate at which data degradation occurs. Paper outlives film, which lasts longer than videotape; videotape is more durable than hard disk drives, which outlast data tape; and data tape lasts longer than DVDs, which may begin to degrade after a couple of years. The transience of digital artifacts and the pace of technological change mean that maintaining valuable digital collections requires careful planning and a sound technical infrastructure. Because data storage technologies are constantly evolving, digital files must be regularly converted into new formats to remain accessible for future generations.
USCDR Preservation Services
The USC Digital Repository (USCDR) provides advanced preservation services for valuable digital collections. Through state-of-the-art digital preservation techniques, many of which were developed and pioneered by the USC Shoah Foundation Institute at USC, the repository is uniquely positioned to ensure the long-term integrity of digital collections, ranging from databases and historical collections to film and video archives.
Community and Capability
The USCDR draws on the wisdom of a large community of digital preservation experts, in academia as well as in the public and private sectors, to assess the best preservation strategy for a particular collection. The repository is dedicated to ensuring that its practices incorporate the best thinking from across the field to provide first-rate preservation services.
The USCDR will monitor digital collections to make sure that they are compatible with the latest content management and technical standards. The repository maintains its systems’ compatibilities with the Library of Congress’ rigorous preservation standards for digital media, including those of the Library of Congress’ National Audio-Visual Conservation Center.
Protecting Data as Technology Evolves
In addition to inevitable physical deterioration, all digital media have an inherent bit-error rate. Although this error rate is typically very small, these errors can grow to be significant in a large digital collection. The USCDR’s data-protection system can virtually eliminate this loss of data by making a digital fingerprint of each file. The repository checks files for any bit-variance against this fingerprint at least once every six months, as well as each time files are created or copied. If the system detects any discrepancy from the original, the USCDR’s staff will correct the issue.
The USCDR can also control against physical deterioration of storage media by replacing data tapes every three years, well before the data begins to deteriorate. Since the storage capacity of new media is always growing, regularly replacing the physical media has the added benefit of increasing storage capacity by as much as a factor of five every two years.