Fault tolerance protocols for parallel programs based on tasks replication

In this paper we propose a fault-tolerant mechanism for parallel programs based on task replication. We use a sequential discrete-event simulator of a distributed system subject to failures to compare a semi-active approach and a passive approach of the protocol. In our model, each time a task of a given parallel program is allocated, a copy of it is stored in a second processor, called the buddy processor. If the original processor fails, the copies of the tasks at the buddy processor will be processed, providing fault tolerance. Some performance measures, such as program execution times and processor utilization factors, are given for the different versions of the mechanism. The performance has been studied as a function of processor degradation, and program and system sizes