$ perldoc BerkeleyDB |grep -i log

    If you don't intend using transactions, locking or logging, then you
         DB_DATA_DIR, DB_LOG_DIR and DB_TMP_DIR
                                   DB_LOG_DIR  => "/home/logs",
         by Berkeley DB will be logged to this file. A useful debug setting
         DB_INIT_LOG
         Initialise the Logging sub-system.