The maximum size of the log file is set using the client.log.maxLogSizeMB field in the /vs/data/vxml/default.cfg file. The value of the field is an integer that is the maximum size in MB, with the following exceptions:
When either the log file (whose name is defined in the field client.log.filename) exceeds the maximum size, or the voice system starts (with an existing log file), the log file is saved automatically to a backup file log_filename.bak, where log_filename is the name of the original log file. In addition, a new log file is generated.