Integrating mass storage and file systems

The authors describe current and anticipated work at the Center for Information Technology Integration at the University of Michigan in developing and integrating mass storage with distributed file systems, specifically with the Andrew File System (AFS). They present a specific approach to integrating AFS with mass storage: they consider the mass store itself to be the file system, not a bag on the side of a disk-based file system. Instead of developing a back-end server to manage the movement of data files between traditional disk-based storage systems (used, in the present case, by AFS) and magnetic-tape or optical-based mass storage systems (of which AFS has little or no knowledge), the authors envision the mass store as a first-class data repository. A traditional disk-based file system serves as a very large cache of the mass store system. On top of that is another, large, high-speed memory cache. All storage other than the mass store is used exclusively for caching. In this approach, cache management policies are of fundamental importance.<>