Systems Architecture Columbia's strategy for digital library architecture may be thought of as a series of discrete layers of technology services, ranging from the storage of bits to specialized interactive applications. This facility is reponsible for the storage of digital data, independent of media type, intellectual content or provenance. At the moment all data is stored on networked disk systems with traditional tape backup. Data is migrated as necessary to take advantage of the most current technology. The AcIS Computing Systems group operates the facility.
Work is now underway to build additional redundancy through mirroring and off-site storage.
Guiding priorities at the repository level are preservation and integrity. We plan to establish a system to better insure authenticity of data through cryptographically signed documents. Access to most of Columbia's digital collections is through web protocols, with distinct items referenced directly by the web servers using simple unix file system or database semantics and operations. But we have also introduced mechanisms to reference items with a new form of identifier. These identifiers are location independent and hopefully more persistent than traditional URL's.