|dc.description.abstract||Grid computing was born in the 1990s, when researchers were looking for a way to share expensive computing resources and experiment equipment. Grid computing is becoming increasingly popular because it promotes the sharing of distributed resources that may be heterogeneous in nature, and it enables scientists and engineering professionals to solve large scale computing problems. In reality, there are already huge numbers of grid computing facilities distributed around the world,
each one having been created to serve a particular group of scientists such as weather forecasters, or a group of users such as stock markets. However, the need to extend the functionalities of current grid systems lends itself to the consideration of grid evolution. This allows the combination of many disjunct grids into a single powerful grid that can operate as one vast computational resource, as well as for grid environments to be flexible, to be able to change and to evolve. The rationale for grid evolution is the current rapid and increasing advances in both software and hardware.
Evolution means adding or removing capabilities. This research defines grid evolution as adding new functions and/or equipment and removing unusable resources that affect the performance of some nodes. This thesis produces a new technique for grid evolution, allowing it to be seamless and to operate at run time. Within grid computing, evolution is an integration of software and hardware and can be of two distinct types, external and internal. Internal evolution occurs inside the grid boundary by migrating special resources such as application software from node to node inside the grid. While external evolution occurs between grids.
This thesis develops a framework for grid evolution that insulates users from the complexities of grids. This framework has at its core a resource broker together with a grid monitor to cope with internal and external evolution, advance reservation, fault tolerance, the monitoring of the grid environment, increased resource utilisation and the high availability of grid resources.
The starting point for the present framework of grid evolution is when the grid receives a job whose requirements do not exist on the required node which triggers grid evolution. If the grid has all the requirements scattered across its nodes, internal evolution enabling the grid to migrate the required resources to the required node in order to satisfy job requirements ensues, but if the grid does not have these resources, external evolution enables the grid either to collect them from other grids
(permanent evolution) or to send the job to other grids for execution (just in time) evolution.
Finally a simulation tool called (EVOSim) has been designed, developed and tested. It is written in Oracle 10g and has been used for the creation of four grids, each of which has a different setup including different nodes, application software, data and polices. Experiments were done by submitting jobs to the grid at run time, and then comparing the results and analysing the performance of those grids that use the approach of evolution with those that do not. The results of these experiments have demonstrated that these features significantly improve the performance of grid environments and provide excellent scheduling results, with a decreasing number of rejected jobs.||en