Performance evaluation of cassette migration mechanism for scalable tape archiver

Recent attention on global environmental changes has stimulated the development of large scale global information systems. Satellite images play a very important role for understanding these global changes, but their data size are very large. Magnetic tape archivers are often used for them because of their capacity, but their capacity cannot be increased except by adding a new archiver which is independent of the others. We designed a scalable tape archiver, which consists of several element archivers and can be extended to any number of archivers. Each element archiver can transfer a cassette to a neighboring one. In the scalable tape archiver, performance strongly depends on data placement and usage of the tape drives. In this paper, we propose several cassette tape migration algorithms to balance the load across the element archivers and also evaluate the performance of the various proposed algorithms through simulation.