No abstract

In a grid and distributed computing environment, data replication is an effective way to improve data accessibility and data accessing efficiency. It is also significant in developing a real-time service monitoring system for a Chinese Scientific Data Grid to guarantee the system stability and data availability. Hierarchical data replication and service monitoring methods are proposed in this paper. The hierarchical data replication method divides the network into different domains and replicates data in local domains. The nodes in a local domain are classified into hierarchies to improve data accessibility according to bandwidth and storage memory space. An extensible agentbased prototype of a hierarchical service monitoring system is presented. The status information of services in the Chinese Scientific Data Grid is collected from the grid nodes based on agent technology and then is transformed into real-time operational pictures for management needs. This paper presents frameworks of the hierarchical data replication and service monitoring methods and gives detailed resolutions. Simulation analyses have demonstrated improved data accessing efficiency and verified the effectiveness of the methods at the same time. 3 THE HIERARCHICAL DATA REPLICATION METHODIn this section, we introduce the detailed framework, system model, and basic algorithm of the hierarchical data replication method and then present simulation results and analysis of the method.

Data replication is an effective way to improve data accessibility in ad hoc networks because of the movement of hosts and the changing of network topology. A new data replication method called Hierarchical Replication Model (HRM) is proposed in this paper. This method selects mobile hosts as data replicas holders taking into account not only data access frequencies and network topology, but also link bandwidth and remaining amount of batteries of hosts. This method groups the network into three hierarchies to improve the data accessibility, and it speeds up the data transmission and increase the data accessing efficiency at the same time. Furthermore, simulation results verify the effectiveness of this method.

It is important to improve data reliability and data access efficiency for data-intensive applications in