Archival Repositories for Digital Libraries

Current libraries use an assortment of uncoordinated and unreliable techniques for storing and managing their digital information. Digital information can be lost for a variety of reasons: magnetic decay, format and device obsolescence, human or system error, among many others. In this thesis, we address the problem of how to build archival repositories (AR). An AR has the following combined key requirements that distinguish it from other repositories. First, digital objects (e.g., documents, technical reports, movies) must be preserved indefinitely, as technologies, file formats, and organizations evolve. Second, ARs will be formed by a confederation of independent organizations. Third, published digital objects have a historical nature, so changes should not be done in-place; instead, they should be recorded in versions. We provide an architecture for ARs that assures long-term archival storage of digital objects. This assurance guarantee is achieved by having a federation of independent but collaborating sites, each managing a collection of digital objects. We also provide a framework for evaluating the reliability and cost of an AR. Finally, we present techniques for efficient access of documents in a federation of independent sites.