In recent years, we have witnessed a growing interest in high performance computing (HPC) using a cluster of workstations. However, many challenges remain to be resolved before these systems become dependable. One of the challenges in a clustered environment is to keep system failure to the minimum level and while achieving the highest possible level of system availability. High-Availability (HA) computing attempts to avoid the problems of unexpected failures through active redundancy and preemptive measures. In this paper, we propose to build HAclusters based model for high performance computing. Our model is based on combination of both HPC and HA concepts, we also propose to investigate further the hardware and the management layers of the HA-HPC cluster design, and the parallel-applications layer (i.e. FT-MPI implementations). In this work, we focus upon the latter layer. We discuss our model, and present our simulation experiments we have carried out to evaluate our proposed model.