1 Troubleshooting Common Issues

This chapter provides common troubleshooting scenarios related to all third-party database plug-ins.

The following topics are provided:

1.1 Third-Party Database Plug-in User's Guides

The user's guides have a lot of important information about the prerequisites and steps required for setting up your target instance for monitoring in Enterprise Manager. If you are having issues with trying to get your plug-in to work with your target instance, review the plug-in user's guide to make sure that you have followed all the steps necessary for making your target instance and the plug-in work together.

1.2 Debugging the Agent

If you have an issue with a target instance which tracks back to the Agent, the two most useful tools will be the Agent logs and the Agent metric browser. By default, the Agent logs at the INFO level; so, to see a more verbose output, you must change the log level to DEBUG. The Agent metric browser, which also needs to be enabled, gives you a real-time view of all of the target instances and Agent settings.

The following topics are presented:

1.2.1 Setting the Log Level

For some issues, the best way to get to the root of the problems is by checking the Agent logs. However, the Agent logs may not have all the information you need by default. It may be necessary to turn on logging at the DEBUG level to get the level of detail you need to figure out the problem. To do that, you need to edit the emd.properties file:


Look for these entries:


Change the second entry to:


Reload or restart the Agent for the setting to take effect.

You can tell the change has taken if the gcagent.log file starts adding statements with the word DEBUG in them.

This setting is good for resolving an outstanding issue; however, once the issue has been resolved, you should return your Agent to log at a level of INFO to maximize performance.

1.2.2 Turning on the Metric Browser

To turn on the metric browser, edit the same emd.properties file as above:


Add these two parameters:


Reload or restart the Agent for the settings to take effect. Then, open a browser window and go to the following URL:


You can use the EMD_URL from the emd.properties file as a model for the URL as it is mostly the same.

This browser interface allows you direct real-time access to the target instances that the Agent monitors. Click on an instance, and then click on any of the metrics in the target instance to view a real-time collection of that metric by the Agent for that target instance. If you are having a problem with one of the metrics, this interface may tell you why, since it will display on the page any error resulting from collecting the metric.

1.2.3 Checking Connectivity from the Agent Host

There are a few simple commands you can execute to tell if the Agent can access the target instance you wish to monitor. Run these commands on your Agent host:

ping <target host>
nslookup <target host>
telnet <target host> port (success means port is active and not blocked)

1.2.4 Using the Test Connection Button

Prior to Enterprise Manager Release, the Test Connection button on the manual discovery page did not work for third-party database plug-ins. This issue has been fixed as part of the release. Because a bug prevented the Test Connection button from working, it should not be relied upon in any earlier versions of Enterprise Manager.

For more information about this bug, See Doc ID 1503064.1 in My Oracle Support:


1.3 JDBC Driver Issues

The following problem and resolution information addresses JDBC driver issues:

1.3.1 Failure in loading Classpath: Could not create instance: <JDBC DRIVER>

Possible Cause: The JDBC Driver Name in target properties and/or the incorrect version of the drivers were used.


  1. Specify the correct JDBC Driver Name in target properties.

  2. Make sure the correct version of the drivers are present in the appropriate directory.

See Also: Failure in Loading Classpath: Could Not Create Instance in the Troubleshooting the IBM DB2 Database Plug-in chapter.

1.3.2 Cannot resolve non-optional query descriptor property [PLUGIN_DEPENDENCIES] (PLUGIN_DEPENDENCIES)

Possible Cause: The jdbcdriver directory was not created correctly and/or the drivers were not put in the jdbcdriver directory.


  1. Make sure the jdbcdriver directory was created correctly.

    • For Microsoft SQL Server, the correct directory is:

    • For IBM DB2 and Sybase ASE, the correct directory is:

  2. Make sure the correct version of the drivers are present in that directory.