A Reliable and Portable Multimedia File System

In this paper we describe a multimedia file system architecture. Research prototype called XPRESS is implemented on Linux. This paper describes detailed design and implementation issues of XPRESS. The features of XPRESS include efficient non-linear editing support, reliability, maintainability and portability. Space management based on byte precision extents enables non-linear editing possible without data copy. In XPRESS, file system metadata like inodes, directories, and free space info are stored in transactional database, thereby guaranteeing metadata consistency against various kinds of system failures. The delegation of transactional metadata management to a database helps fast development of reliable file system. While XPRESS metadata is stored thru a guest database, XPRESS controls physical layout of file contents by itself to support real-time streaming performance. We propose a method to optimize data placement considering the disk drive’s seek curve characteristics. Experiments show that XPRESS has I/O bandwidth competitive to Linux XFS real-time extension and is more responsive than XFS real-time extension. This indicates feasibility of the XPRESS’s architecture by removing the concerns of performance penalties of user level execution and using database. XPRESS is a good framework for building a high performance multimedia file system. Possible future extensions includes encryption, access control list, and new file system services.