Optimization of a Real-Time Primary-Backup Replication Service

The primary-backup replication model is one of the commonly adopted approaches to providing fault tolerant data services. Its extension to the real-time environment, however, imposes the additional constraint of timing predictability, which requires a bounded overhead for managing redundancy. This paper discusses the trade-o between reducing system overhead and increasing (temporal) consistency between the primary and backup, and explores ways to optimize such a system to minimize either the inconsistency or the system overhead while maintaining the temporal consistency guarantees of the system. An implementation built on top of the existing RTPB model [20] was developed within the x-kernel architecture on the Mach OSF platform running MK 7.2. Results of an experimental evaluation of the proposed optimization techniques are discussed.