The history of computing can be viewed as a constant search for computational power. As soon as a new, more powerful, computer is developed a larger problem to be solved appears on the horizon. This need for computational power, instead of leveling off, is growing day by day. During recent decades different high performance computer systems attempted to satisfy the power-hungry users. Although vector computers provided the breakthrough needed for the computational research to emerge as an independent science, they were only a partial answer as they could deliver top performance only for a few classes of problems.
Symmetric multiprocessors are attractive, but they suffer from the scalability problem.
Distributed systems are scalable but they do not offer ease of use or means for fast communication, which are essential requirements for efficient execution of parallel applications. Another trend which is also worth mentioning in this context is the increased need for computing power in commercial applications coupled with the high cost and low accessibility of traditional supercomputers. As a whole, clusters are becoming an alternative to MPPs and supercomputers in many areas of application. A half of the selected papers will appear in PDCP and the remaining half appears in this issue. The focus of this Special Issue will be on both hardware and software aspects of cluster computing.