— Semantic file systems enhance standard file systems with the ability of file searching based on file semantics. The users interact with semantic file systems not only by executing browsing tasks on a hierarchy of directories but also by executing retrieval tasks like the way that information retrieval systems usually do. In this paper, we characterize semantic file systems by comparing them with other information systems, such as information retrieval systems, Semantic Web and Semantic Desktop. We identify the issues in designing a semantic file system and propose an example ontology-based solution for these issues.