Maintaining a Failover Cluster
After you have installed a SQL Server failover cluster, you can change or repair it using the SQL Server Setup program. For example, you can add additional nodes to a failover cluster instance, run a clustered instance as a stand-alone instance, or remove a node from a clustered instance configuration.
SQL Server Setup gives you the option of maintaining an existing failover cluster instance. If you choose this option, you can add other nodes to your failover cluster configuration by running SQL Server Setup on the computer that you want to add to the cluster. For more information, see How to: Create a New SQL Server Failover Cluster (Setup) and How to: Add or Remove Nodes in a SQL Server Failover Cluster (Setup).
You can remove a node from a failover cluster configuration by running SQL Server Setup on the computer that you want to remove from the cluster. Each node in a SQL Server failover cluster configuration is considered a peer without dependencies on other nodes on the cluster, and you can remove any node. A damaged node does not have to be available to be removed, and the removal process does not uninstall the SQL Server binaries from the unavailable node. A removed node can be added back to a failover cluster at any time. For more information, see How to: Add or Remove Nodes in a SQL Server Failover Cluster (Setup).
Usually, a clustered instance of SQL Server runs under the control of Microsoft Cluster Service (MSCS). However, it may be necessary to run a clustered instance of SQL Server as a stand-alone instance. For example, to run a SQL Server instance in single-user mode, it may be necessary to run a clustered instance of SQL Server as a stand-alone instance from a command prompt instead of starting SQL Server through MSCS. To connect to a clustered instance of SQL Server in stand-alone mode using sockets, both the IP address and network name resources must be online for the failover cluster on which the instance was installed.
If these resources cannot be online, connect using Named Pipes. You must create an alias on the client side to communicate with the pipe name on which the instance of SQL Server is listening. Use SQL Server Configuration Manager to find out the pipe name.
You should not change passwords for any of the SQL Server service accounts when a failover cluster node is down or offline. If you must do this, you must reset the password again by using SQL Server Configuration Manager when all nodes are back online.
If the service account for SQL Server is not an administrator in your cluster, the administrative shares cannot be deleted on any nodes of the cluster. The administrative shares must be available in a cluster for SQL Server to function.
Do not use the same account for the SQL Server service account and the MSCS account. If the password changes for the MSCS account, your SQL Server installation will fail.
On Windows Server 2008, service SIDs are used for SQL Server service accounts. For more information, see Setting Up Windows Service Accounts.