Tuesday, June 28, 2016

Protecting the Long-Term Viability of Digital Composite Objects through Format Migration

Protecting the Long-Term Viability of Digital Composite Objects through Format Migration. Elizabeth Roke, Dorothy Waugh. iPres 2015 Poster. November, 2015.
     The poster discusses work done at Emory University’s Manuscript, Archives, and Rare Book Library to "review policy on disk image file formats used to capture and store digital content in our Fedora repository". The goal was to to migrate existing disk images to formats more suitable for long-term digital preservation. Trusted Repositories Audit & Certification (TRAC) requires that digital repositories monitor changes in technology in order to respond to changes. Advanced Forensic Format offered a good solution for capturing forensic disk images along with disk image metadata, but Libewf by Joachim Metz, which is a library of tools to access the Expert Witness Compression Format (EWF) has replaced it. They have decided to acquire raw disk images, or when not possible, to use tar files, because the disk images may be less vulnerable to obsolescence.

In attempting to migrate formats, they had to develop methods for migrating the files setup the repository to accept the new files. They also rely on PREMIS metadata.  The migration of disk images from a proprietary or unsupported format to a raw file format has made it easier for us to manage and preserve these objects and mitigates the threat of obsolescence for the near term. There have been some consequences. Some metadata is no longer available. Also, the process will be more complicated and require other workflows, and files will no longer contain embedded metadata. "The migration to a raw file format has made the digital file itself easier to preserve."

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