Content Summary : This SQL Server 2005 Magazine white paper is written for a technical audience that needs to understand failover clustering, and that wants to know how SQL Server 2005 is implemented on a failover cluster, how to install and configure SQL Server 2005 for failover clus-tering, and best practices for SQL Server 2005 clustering. As SQL Server 2005 environments move from smaller installations to larger mission-critical enterprises, the need for the database environ-ment to be highly available becomes more apparent. SQL Server 2005 has many different mechanisms to achieve high availability. But one of the most commonly used methods to achieve a highly available mission-critical database environment is SQL Server 2005’s ability to make use of clustered environments. Background on SQL Server Clustering: What Is It? Failover clusters are a Windows solution that allows administrators to create a functional grouping of servers that can act as surrogate hosts for applications running on one or more of the servers in case of unavail-ability at the server or application level. Simply put, clusters provide high availability for applications running on the servers. This high avail-ability does not guarantee non-stop operations because there is some down-time while the failover occurs; nor does it guarantee the same level of performance after a failover. What a clustered solution guaran-tees is that cluster-aware applications will be monitored by the cluster-ing software and the application and its resources and then automati-cally recovered from many failure conditions by running the application on another server.