The Monitored Server - SQL Server host not defined alarm is raised for:

  1. A Microsoft Cluster Server (MSCS)
  2. Where the SQL Server Connection Details dialog Connection field is set to Cluster (monitor active node).
  3. And the active cluster node is NOT in the list of available OS connections in the SQL Server Connection Details dialog Linked OS Connection drop down field.

For a SQL Server cluster that uses the Cluster (monitor active node) feature there must be a Windows connection for each Windows node in the cluster. Refer to the online help SQL Server | Connect | Connection Details for more information. This alarm clears once the Windows connection has been created.