Taming the downtime: high availability in Sybase ASE 12

The new companion architecture in Sybase Adaptive Server Enterprise (ASE) 12 for high availability is supported on a 2-node cluster with each node running a separate ASE 12 server in a companion configuration. This architecture is designed to withstand a single point of failure for unplanned outages, and allow both nodes to be used for productive workload during normal operation. It enables fast failover and data recovery, supports automatic client migration during failure, and integrates seamlessly with adjoining layers in multi-tier architecture. It supports single system presentation of data for applications, and presents a rich set of features/infrastructure to reduce the planned downtime. During failover and failback, only the persistent data component is moved between the companion ASEs, making it fast and efficient. Introducing the proxy databases, this architecture enables user databases to be visible and accessible from either of the companions by shipping the queries to the appropriate node and returning the results to the client.