In this Document

APPLIES TO:

PURPOSE

You sometimes face Problems with the Data Guard Broker. It looks like the DMON-Processes of the Primary and Standby Databases cannot reach each other, Log Transport fails or any Commands in DGMGRL like 'enable configuration'. This Guide explains how the Data Guard Broker connects to the Databases and how to Troubleshoot.

TROUBLESHOOTING STEPS

Data Guard Broker Connection Model

When you start the Data Guard Broker (DMON)-Process on your Primary and Standby Database, it will start and register Services on the Local Listener:

_DGB.: This Service is used by the DMON-Processes to communicate between each other

_XPT.: This Service is used for Log Transport Services and FAL (corresponding Initialization Parameters are set once a Configuration is enabled) - (Oracle 10g only)

Starting with Oracle 11.1.0.x you can use your own Service and/or TNS-Alias used for Log Transport Services and FAL (corresponding Initialization Parameters are set once a Configuration is enabled). This Service is specified by the Data Guard Broker Property 'DGConnectIdentifier'. If you specify a TNS-Alias here you have to ensure this Alias is configured on all TNSNAMES.ORA's in the Data Guard Configuration.

If you want to perform Operations with the Data Guard Broker that require a Restart of any Database using DGMGRL (like Switchover), you also have to register an additional Static Service with the local Listener

_DGMGRL.: This Service is used to connect to a Database by the Data Guard Broker while it is shutdown

Starting with Oracle 11.2.0.x you can also setup and use your own Static Listener Entry. You will then have to set the Data Guard Broker Property 'StaticConnectIdentifier' to this Entry. The default Value still points to _DGMGRL-Entry.

Troubleshooting:

a) Problems with the Log Transport Services/FAL:

• Review ALERT.LOG and DRC.LOG-Files for exact Error
• _XPT. is registered with the Local Listener (10g only)
• Initialization Parameter 'local_listener' and Data Guard Broker Property 'LocalListenerAddress' is set and pointing to the correct Listener (10g only)
• Verify you have not setup further duplicate Log Transport Services
• Ensure the TNS-Alias if specified in 'DGConnectIdentifier' is setup on all TNSNAMES.ORA in the Data Guard Environment (11g onward)
• Verify that the specified Service in the 'DGConnectIdentifier' exists and is registered with the corresponding Listener

b) DMON-Communication

• Review DRC.LOG from all Instances for any Issues
• _DGB. is registered with the Local Listener
• Initialization Parameter 'local_listener' and Data Guard Broker Property 'LocalListenerAddress' is set and pointing to the correct Listener (10g only)
• If this is all fine and you cannot determine any Cause, try to set        

and restart the Data Guard Broker Process. This will record all Connectstrings used by the Data Guard Broker in the DRC.LOG-Files. So you can see which exact Connect is actually being used by the Data Guard Broker (10g)

• Set the Data Guard Broker Configuration Property 'TraceLevel' to 'SUPPORT' to gather DMON Tracing (11.2.0.3 onward)

  -> It replaces the Event 16634 and can be set dynamically for the Configuration. Note that since it is Configuration-specific, it gathers Tracing Information from all Databases. The default Value is 'USER'. The Tracing Information is still further logged in the DRC.LOG.

To enable the Tracing run

   -> Tracing will be enabled immediately, there is no restart of the Data Guard Broker Processes required.

To disable Tracing again once the required Information is gathered, you can reset the Property to its default Value: