Clustering Support and Replication Management for Scalable Network Services Kai Shen Tao Yang, and Lingkun Chu Department of Computer Science Department of Computer Science University of Rochester University of California, Santa Barbara The ubiquity of the Internet and various intranets has brought about widespread availability of online services and applications accessible through the network. Cluster-based network services has been rapidly emerging due to their cost-effectiveness in achieving high availability and incremental scalability. This paper presents the design and implementation of the Neptune middleware system that provides clustering support and replication management for scalable network services. Neptune employs a loosely-connected and functionally-symmetric clustering architecture to achieve high scalability and robustness. It shields the clustering complexities from application developers through simple programming interfaces. In addition, Neptune provides replication management with flexible replication consistency support at the clustering middleware level. Such support can be easily applied to a large number of applications with different underlying data management mechanisms or service semantics. The system has been implemented on Linux and Solaris clusters, where a number of applications have been successfully deployed. Our evaluations demonstrate the system performance and smooth failure recovery achieved by proposed techniques.