Oracle Database for Windows background threads use trace files to record occurrences and exceptions of database operations, and errors.
Background thread trace files are created and stored in the Automatic Diagnostic Repository (ADR) directory specified by the parameter DIAGNOSTIC_DEST in the initialization parameter file.
Oracle Database creates a different trace file for each foreground and background thread. The name of the trace file contains the name of the thread, followed by the extension ".trc". The following are examples of foreground trace file names:
ops_ora_5804.trc
ops_ora_4160.trc
The following are the examples of the background trace file names:
ops_pmon_1556.trc
ops_mmon_3768.trc
ops_lgwr_2356.trc
ops_dbw0_132.trc
Trace files are also created for user threads and stored in the ADR directory specified by the parameter DIAGNOSTIC_DEST in the initialization parameter file. Trace files for user threads have the form oraxxxxx.trc, where xxxxx is a 5-digit number indicating the Windows thread ID.