I have checked the database mirror alert: 'DB State:Mirroring State Changes'. This alert runs query 'SELECT * from DATABASE_MIRRORING_STATE_CHANGE'. And I think it checks the query via a namespace: '\\.\root\Microsoft\SqlServer\ServerEvents\MSSQLSERVER'. 1) How often is this alert run or checked as there is no set shcedule? 2) How does this alert work? I don't know how SQL Server checks to see if there are database mirror state changes using the above query and namespace.