Real-Time Primary-Backup (RTPB) Replication with Temporal Consistency Guarantees

This paper presents a real-time primary-backup (RTPB) replication scheme for supporting faulttolerant real-time applications. It formally de nes two types of temporal consistency, namely external temporal consistency and inter-object temporal consistency. By introducing a key concept called phase variance, we are able to build our temporal consistency models and derive necessary and su cient conditions that can be used as the basis for update and transmission scheduling that achieve temporal consistency guarantees. Furthermore, we prove that the term phase variance used in the models can be bounded under various scheduling algorithms, namely EDF, Rate Monotonic [13], and Distance-Constrained Scheduling [9]. A RTPB implementation was developed within the x-kernel architecture on the MK 7.2 microkernel and the results of a detailed performance evaluation is also discussed.