IBM User Guide for Java V7 on Windows > Troubleshooting and support > Using diagnostic tools > The Diagnostics Collector
Verifying your Java diagnostics configuration
When you enable the command-line option -Xdiagnosticscollector, a diagnostic configuration check runs at Java™ VM start. If any settings disable the collection of key Java diagnostic data, a warning is reported.
The aim of the diagnostic configuration check is to avoid the situation where a problem occurs after a long time, but diagnostic data is missing because the collection of diagnostic data was inadvertently switched off. Diagnostic configuration check warnings are reported on stderr and in the Diagnostics Collector log file. A copy of the log file is stored in the java.check.<timestamp>.<pid>.zip output file.
If you do not see any warning messages, it means that the Diagnostics Collector has not found any settings that disable diagnostic data collection. The Diagnostics Collector log file stored in java.check.<timestamp>.<pid>.zip gives the full record of settings that have been checked.
For extra thorough checking, the Diagnostics Collector can trigger a Java dump. The dump provides information about the command-line options and current Java system properties. It is worth running this check occasionally, as there are command-line options and Java system properties that can disable significant parts of the Java diagnostic data set. To enable the use of a Java dump for diagnostic configuration checking, set the config.check.javacore option to true in the settings file. For more information, see Diagnostics Collector settings.
For all platforms, the diagnostic configuration check examines environment variables that can disable Java diagnostic data collection. For reference purposes, the full list of current environment variables and their values is stored in the Diagnostics Collector log file.
Parent: The Diagnostics Collector