Preservation strategies
Bitstream copying
The Libraries creates multiple copies of all information contained in the Libraries’ digital repositories, for use in the event of data loss. In combination with regular fixity checks, which identify potentially damaged content, this process assists with ensuring the integrity of content, and provides a foundation for its disaster recovery plans.
Documentation of file formats
Inventories of content identify file formats and other characteristics including the PRONOM identifier in the UK National Archive’s online file format registry. This association ensures that information is always available on the internal structure of the file, and can be further used to determine when the format migration activity should take place in order to mitigate the risks posed by the obsolete file formats.
Fixity checking
If not provided with the content, an initial fixity value is generated for all materials subject for preservation. These values are recalculated and compared at certain points of time to verify that the content has not changed. This activity, when combined with bit stream copying enables the repository managers to identify damaged or corrupted content, and to revert to a valid version of the object from a previous point in time.
Format migrations
When the Libraries perceive that a file format is at risk of obsolescence, a new version of this content will be created in a format more suited for long-term preservation and use. This transformation may consist of migration to a newer version of the content’s existing format, or transformation to a different format altogether. In all cases, preservation of the object’s intellectual content will be prioritized over the preservation of a specific presentation style.
Normalization
Upon ingest, materials not conforming to the Libraries’ accepted standards may be converted to one of the preferred formats. To the extent possible, the Libraries will attempt to preserve the essential characteristics of the object. In cases requiring compromise, transformations that maintain the content of the object will be prioritized over those that preserve the presentation. [This process is done on an as needed basis]
Preservation-friendly file formats
The Libraries is committed to the use of file formats that support long term sustainability. In general, the considerations for selecting file formats include the “openness” of the file format, its level of support as a preservation format in the academic/scholarly community, and how well the format is suited for format migration later on.
Adapted from the Preservation Activities section of McMaster University's Digital Preservation Implementation Plan.
Contact us
If you have any questions about digital preservation at the University of Minnesota Libraries please contact the digital preservation team at lib-dp@umn.edu and we will be happy to assist you.