John Heidemann

Stackable Layers: an Architecture for File System Development

TitleStackable Layers: an Architecture for File System Development
Publication TypeThesis
Year of Publication1991
AuthorsJ. S. Heidemann
Number of Pages128

This thesis proposes the \em stackable layers\/ method of file system design. This approach constructs file systems from a number of independently developed \em layers. Each layer is bounded by a symmetric interface, syntactically identical above and below. Layers combine in \em stacks, linear or tree-shaped collections, each layer building on the functionality of those beneath it. Stackable filing improves file system development in several ways. Stacking encourages code re-use by building upon already existing layers. Incremental improvement is possible by substitution of existing layers. The layer interface is extensible, allowing new operations to be easily added by third-parties. Each operation is carefully described, permitting existing layers to adjust automatically to the addition of new operations. The feasibility of stackable filing is demonstrated by the development of a prototype layer interface and several file system layers. The performance of multi-layer stacks is found comparable to that of monolithic file systems. Through the re-use of existing services, we find development of new filing services with stackable layers significantly easier than development with traditional methods.