An Efficient Approach for State Sharing in Server Pools

Abstract

Many Internet services require high availability. That is, downtimes cause loss of money (e.g. electronic shops) or damages of equipment (e.g. control systems for production processes). Server pooling provides a high availability solution using multiple redundant servers. If one server fails, the service is continued by another one. A big challenge for server pooling is efficient state sharing. That is, servers contain states for each client (e.g. user identity or media position). To continue the service in case of a failover, the new server has to know the old server’s state. The goal of this paper is to present an efficient, simple and scalable approach, applicable to a large range of server pooling applications, that provides secure transfer of states by the client itself, using an extended cookie mechanism. Finally, it also provides implementation considerations. Keywords: high availability, server pooling, state sharing, client, server