PERFORMANCE OF DYNAMIC REPLICATION AND MIGRATION SCHEMES FOR A GLOBAL WEB HOSTING SERVICE

Abstract

As commercial interest in the Internet grows, more and more companies are offering the service of hosting and providing access to information that belongs to third-party information provider;. In the future, successful hosting services may host millions of objects on thousands of servers deployed around the globe. To provide reasonable access performance to popular resources, these resources will have to be mirrored on multiple servers. This dissertation explores schemes for dynamic replication and migration of web objects in the context of an Internet hosting service. It describes a replica placement algorithm for deciding the location and number of replicas of an object as well as request distribution schemes for choosing among currently available replicas. These algorithms rely on the information available in databases maintained by Internet routers and attempts to place replicas in the vicinity of a majority of requests while ensuring at the same time that no servers be overloaded. We have simulated the algorithms using synthetic workloads on the backbone topology of Worldnet, one of the largest commercial Internet Service Providers. Measurement and analysis show that the dynamic replication scheme is effective in ilinilnating hot:spots among servers and achieves a significant reduction of backbone traffic and server response time at the expense of creating only a small number of extra replicas and imposing only a low network overhead.