Abstract
As the power of computer progresses, software gets increasingly more complex and intelligent. Meanwhile, network infrastructure has also improved at a high speed. Because of these advancements, there is a strong interest in sharing computing resources scattered over many different places. Therefore, the large-scale resources sharing and management become very important issues.At the beginning, concept of Grid is described first, followed by the introduction of the components of OGSA (Open Grid Service Architecture) standard, OGSI (Open Grid Service Infrastructure) standard, Globus Toolkits, and relationship among them. OGSA standard maps the path of integrating resources into a Grid. OGSI standard is the most important component of OGSA. Globus Toolkits are the first full-scale implementation of the OGSI standard.The sharing of computational resources is the primary interest of resource sharing. A typical case is the so-called cluster, which consists of a group of computers working together to solve a large computation-intensive application. To solve larger applications, cluster of cluster which cinsists a group of clusters is developed. To facilitate MPI programs to function properly across clusters, MPI extensions, such as MPICH-Globus2 and MPICH-VMI, have been introduced and are briefly discussed here. How these MPI implementations work across clusters behind firewalls is also disscussed. In addition, an optimization of PACX-MPI for data transmission between two clusters has been implemented. Communications between two clusters are studied and handled with multithread. System throughputs are measured by use of NAS Parallel Benchmark and Persistence of Vision Raytracer.