Log files are archived for the Channel service, the Lookup service, the file repository, and individual Group Chat clients. You may need to retrieve these files for troubleshooting purposes. To save an archived log file for future troubleshooting or other reasons, copy the log file from the Logs folder to a new location.
The current and archived log files for the Lookup and Channel services reside on the same computer as the services. The file repository log file is found at the same location, and it is named WebService.log. If you accepted the default location during installation, you can find the log files for each computer at: %programfiles%\Microsoft Office Communications Server 2007 R2\~\Logs. Logs for an individual Group Chat clients are located on the computer where the Group Chat client is installed.
For details about log files and enabling logging and configuring log levels, see Setting Log Levels for the Channel Service, Lookup Service, or Web Service.