lot of relay log formation in mysql5.6
Two possible reasons seem to stick out,  ensure your server_id is different on both the master and the slave.  This is to be defined at startup in the cnf file.

Another option is you specified a very tiny max_binlog_size or max_relay_log_size, ensure the values are what you want and not off by an order of magnitude (eg. 512k instead of 512M)