First failure data capture (FFDC)
The FFDC feature instantly collects information about events and conditions that might lead up to a failure. The captured data in these files can be used to analyze a problem. FFDC is intended primarily for use by IBM Service. The presence of an FFDC message does not always mean there is a problem. In cases where normal recovery occurs, no further action is needed. After a maximum number of days, these files are automatically deleted from your system.
After the information is collected, and saved in a log file, FFDC returns
control to the affected engines.
By default, a FFDC log file is automatically purged seven days it is created. You can configure the amount of days between purges if you are concerned about the amount of space that the FFDC log files are using.
- The WebSphere FFDC, which is the legacy FFDC implementation. This FFDC can only be used in WebSphere products.
- The IBM FFDC, which is a more componentized, and more generic implementation that depends solely on the JDK. This FFDC can be used in client processes and by non-WebSphere products, because it is pluggable with non-WebSphere data collectors, formatters, providers, and listeners.
- <file_name>, where file_name is either be the
name of a single file or a directory path.
- If file_name exists and is the name of a single file, all of the incident and summary reporting information that FFDC collects is appended into that file.
- If file_name exists and is a directory path, whenever an incident occurs, a new file is created in that directory and all of the incident and summary reporting information for that incident is written into this newly created file. The incident is also added to the summary report in this directory.
- If file_name ends in a file separator (\ or /). but a file with the specified
name does not exist, a directory called file_name is created. Then, whenever an
incident occurs, a new file is created in that directory and all of the incident and summary
reporting information for that incident is written into this newly created file. The incident is
also added to the summary report in this directory. Example of use:
Name: com.ibm.ffdc.log Value: C:\my_FFDC_CP\
- If file_name does not end in a file separator (\ or /). and a file with the
specified name does not exist, a single file is created and given the specified name. All of the
incident and summary reporting information that FFDC collects is then appended into that file. Example of use:
Name: com.ibm.ffdc.log Value: C:\my_FFDC_CP_log
- System.out, which appends the incidents and summary report information to the stdout output stream.
- System.err, which append the incidents and summary report information to the stderr output stream. System.err is the default value for the com.ibm.ffdc.log Java environment variable.
- Suppress, which causes all FFDC collected information to be discarded.
Specifying a value for the com.ibm.ffdc.log JVM environment variable is the only configuration change that you need to make to exploit the OnDirProvider functionality. The new FFDC also provides mechanisms to overly choose this provider or to use your own WebSphere provider.
The com.ibm.ffdc.log variable can also be used to redirect the FFDC incidents and summary created in the product. If you want to use the com.ibm.ffdc.log variable for this purpose, you must specify a directory as the variable value. Therefore, it is recommended that, if this variable is used in a WebSphere Application Server environment, the specification of this variable end in a file separator (/ or \\) to avoid conflicts.