Configuring collection of detailed diagnostic information

If you have IBM® Cloud Application Performance Management, Advanced, you can use the data collector to collect detailed diagnostic information on the monitored application server instance. To configure the behavior of the diagnostic data collection, including the amount of diagnostic information that the data collector stores, customize the gdc_custom.properties configuration file.

About this task

You can find the gdc_custom.properties file in the dc_home/runtime/<server_name>/custom/gdc directory.

The following examples describe how to use the properties in the gdc_custom.properties configuration file to do the following things:

You can also set other properties in the gdc_custom.properties file to customize collection of diagnostic data. Refer to the comments in the file that describe the properties.

Remember: After you complete editing the gdc_custom.properties file, you must restart the monitored application server instance for the changes to take effect.

Setting limits for the size and number of detailed information files

About this task

The data collector stores diagnostic information in a number of files. By default, it stores 100 files; if 100 files are already stored and a new file is created, the oldest file is deleted. The data collector creates a new file every 15 minutes, or when the size of the current file exceeds 200 megabytes. When the total size of the directory that contains the files exceeds 2 gigabytes, the data collector deletes the oldest file.

Procedure

You can change the following settings in the dc_home/runtime/<server_name>/custom/gdc/gdc_custom.properties file:

  • To set the maximum number of files with diagnostic information, set the com.ibm.itcam.gdc.dfe.filelimit property.
    For example:
    com.ibm.itcam.gdc.dfe.filelimit=100
  • To set the time, in minutes, after which the data collector creates a new diagnostic data file, set the com.ibm.itcam.gdc.dfe.frequency property.
    For example: 
    com.ibm.itcam.gdc.dfe.frequency=15
  • To set the maximum diagnostic data file size, in megabytes, set the dfe.file.maxlimit property.
    For example:
    dfe.file.maxlimit=200
    If the current diagnostic data file reaches this size, the data collector creates a new diagnostic data file.
  • To set the maximum total size of all data files, in bytes, set the trace.dir.size.limit property.
    For example:
    trace.dir.size.limit=2147483648
    If the sum of the sizes of all the diagnostic data files exceeds this value, the data collector deletes the oldest data file. The minimum total size is 25 megabytes.

Setting full or partial collection of request and method diagnostic data

About this task

The data collector has the following default settings:
  • The data collector collects diagnostic data only for the selected requests. The selection (sampling) of the requests aims to include all errors and some good requests.
  • Method data collection is disabled at server startup.
  • When method data collection is enabled, the data collector gathers method data only for some requests (of those for which diagnostic data is collected). This further selection (sampling) again aims to include all errors and some good requests.
Important: Changing these settings affects performance of the application server. On production servers, the performance degradation might be critical.

Procedure

You can change these settings by using properties in the dc_home/runtime/<server_name>/custom/gdc/gdc_custom.properties file.

  • To enable method data collection, set the property as follows: 
    dfe.enable.methoddata=true
    Tip: You can also use the Agent Configuration page to dynamically enable or disable the method trace data collection.
  • To collect diagnostic data for every request, disable the sampling by setting the property as follows: 
    dc.sampling.enable=false
  • To enable method data collection for every request for which diagnostic data is collected, set the property as follows: 
    dc.sampling.enable=false
dc.sampling.methsampler.enabled=false
    Remember: The dc.sampling.methsampler.enabled property takes effect only when method data collection is enabled on the Agent Configuration page or by the dfe.enable.methoddata property.