Electronic libraries and optical jukebox server scheduling
Patrick E. Mantey, David E. Levy · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1992
The economics of large electronic libraries requires a hierarchy of storage devices, where the lowest level contains the most data and has the poorest performance characteristics. In today''s electronic library systems, this is the role of the optical jukebox. Performance obtainable from an electronic library is a function of many system and application characteristics. We are addressing performance of client/server libraries where retrieval is the primary interaction of users with the library. When the documents to be retrieved reside on the optical media managed by the jukebox server, and nowhere else in the hierarchy, then the retrieval of these documents becomes a batch task. This is acceptable for many users and applications environments: for professionals who are simultaneously at various stages of many tasks and can anticipate the next ones, and for clerical workers in an environment controlled by work- flow (and not interrupt driven). Scheduling of batch retrievals of documents from archival storage need not be in the same order as requests. This paper proposes a cyclic scheduling for retrieval of documents from the optical jukebox, and shows by simulation that this cyclic scheduling can offer significant performance improvement over that obtained by FCFS scheduling of the jukebox.