Reliability and Performance Models for Grid Computing

Introduction

Grid computing (Foster & Kesselman, 2003) is a newly developed technology for complex systems with large-scale resource sharing, wide-area communication, and multi-institutional collaboration etc, see e.g. Kumar (2000), Das et al. (2001), Foster et al. (2001, 2002) and Berman et al. (2003). Many experts believe that the grid technologies will offer a second chance to fulfill the promises of the Internet.

The real and specific problem that underlies the Grid concept is coordinated resource sharing and problem solving in dynamic, multi-institutional virtual organizations (Foster et al., 2001). The sharing that we are concerned with is not primarily file exchange but rather direct access to computers, software, data, and other resources. This is required by a range of collaborative problem-solving and resource-brokering strategies emerging in industry, science, and engineering. This sharing is highly controlled by the resource management system (Livny & Raman, 1998), with resource providers and consumers defining what is shared, who is allowed to share, and the conditions under which the sharing occurs.

Recently, the Open Grid Service Architecture (Foster et al., 2002) enables the integration of services and resources across distributed, heterogeneous, dynamic, virtual organizations. A grid service is desired to complete a set of programs under the circumstances of grid computing. The programs may require using remote resources that are distributed. However, the programs initially do not know the site information of those remote resources in such a large-scale computing environment, so the resource management system (the brain of the grid) plays an important role in managing the pool of shared resources, in matching the programs to their requested resources, and in controlling them to reach and use the resources through wide-area network.

The structure and functions of the resource management system (RMS) in the grid have been introduced in details by Livny & Raman (1998), Cao et al. (2002), Krauter et al. (2002) and Nabrzyski et al. (2003). Briefly stated, the programs in a grid service send their requests for resources to the RMS. The RMS adds these requests into the request queue (Livny & Raman, 1998). Then, the requests are waiting in the queue for the matching service of the RMS for a period of time (called waiting time), see e.g. Abramson et al. (2002). In the matching service, the RMS matches the requests to the shared resources in the grid (Ding et al., 2002) and then builds the connection between the programs and their required resources. Thereafter, the programs can obtain access to the remote resources and exchange information with them through the channels. The grid security mechanism then operates to control the resource access through the Certification, Authorization and Authentication, which constitute various logical connections that causes dynamicity in the network topology.

Although the developmental tools and infrastructures for the grid have been widely studied (Foster & Kesselman, 2003), grid reliability analysis and evaluation are not easy because of its complexity, largeness and stiffness. The gird computing contains different types of failures that can make a service unreliable, such as blocking failures, time-out failures, matching failures, network failures, program failures and resource failures. This chapter thoroughly analyzes these failures.

Usually the grid performance measure is defined as the task execution time (service time). This index can be significantly improved by using the RMS that divides a task into a set of subtasks which can be executed in parallel by multiple online resources. Many complicated and time-consuming tasks that could not be implemented before are working well under the grid environment now.