Adaptive real-time file handling in local area networks

Current and future needs in building adaptive real-time systems are analyzed and a series of design requirements for their hardware/interconnection, operating system, and application levels are formulated. The major features of the corresponding integrated system design model are described. On the operating system level, services are rendered by the DRAGON SLAYER distributed operating system to both meet real-time constraints and provide for high availability in a hazardous environment. It also allows for replicating, relocating, or deleting file copies. Such copies may also assume a different status regarding the recency of their information. Depending on the deadline failure history, status changes as well as file replication, deletion, or relocation are analyzed and managed by local file assigners, based on cost and time delay criteria. Also reported is a sensitivity study that shows how promptly the model file system reacts to changing environmental situations (changing request patterns). Findings are discussed, and future work is outlined