On Fully Decentralized Resource Discovery in Grid Environments

Computational grids provide mechanisms for sharing and accessing large and heterogeneous collections of remote resources such as computers, online instruments, storage space, data, and applications. Resources are identified based on a set of desired attributes. Resource attributes have various degrees of dynamism, from mostly static attributes, like operating system version, to highly dynamic ones, like network bandwidth or CPU load. In this paper we propose a peer-to-peer architecture for resource discovery in a large and dynamic collection of resources. We evaluate a set of request-forwarding algorithms in a fully decentralized architecture, designed to accommodate heterogeneity (in both sharing policies and resource types) and dynamism. For this, we build a testbed that models two usage characteristics: (1) resource distribution on peers, that varies in the number and the frequency of shared resources; and (2) various requests patterns for resources. We analyzed our resource discovery mechanisms on up to 5000 peers, where each peer provides information about at least one resource. We learned that a decentralized approach is not only desirable from administrative reasons, but it is also supported by promising performance results. Our results also allow us to characterize the correlation between resource discovery performance and sharing characteristics.