GUI Tool
The GUI version of the Compare Data tool generates one log file per GUI session when you have set the Type of logging to do HCOSS option to either Write log messages just to file or Write log messages to both console and file.
MFTestConversion Command
When running the Compare Data tool from the command line, HCOSS generates a log file when you have set the TYPELOG directive to either FILE or BOTH, and when TYPELOG is not specified, defaults to the value of the Type of logging to do HCOSS option.
logFileDir\CompareTasks
where logFileDir is the value of the Directory to write log files to HCOSS option.