The EFTOS voting farm: a software tool for fault masking in message passing parallel environments

We present a set of C functions implementing a distributed software voting mechanism for EPX or similar message passing environments, and we place it within the EFTOS framework (Embedded Fault-Tolerant Supercomputing) of software tools for enhancing the dependability of a user application. The described mechanism can be used for instance to implement restoring organs, i.e. modular redundancy systems with N-replicated voters. We show that, besides structural design goals like fault transparency, this tool achieves replication transparency, a high degree of flexibility and ease of use, good performance, as well as the possibility to combine fault masking with recovery techniques.