When you are using mysqldump, you can get the binary logs coordinates of the backup at the point-in-time of the the mysqldump's start.

Just add the [--master-data option][1]

    mysqldump --master-data=2 --flush-logs --single-transaction...

Using `--master-data=2` will record the binary log filename and position in the form of a  `CHANGE MASTER TO` command. It is recorded as a comment.

Using `--master-data=1` will also record the binary log filename and position in the form of a  `CHANGE MASTER TO` command. It is not recorded as a comment, but as a command that will be executed when you reload the mysqldump.

In both cases, you can always find that `CHANGE MASTER TO` command on line 23 of the dump. I mentioned this before in my old post http://dba.stackexchange.com/questions/22623/mysql-exec-master-log-pos-value-greater-than-read-master-log-pos/22636#22636 under the **heading "BUT WAIT..."**

To retrieve that line from a mysqldump file named `myfullbackup.sql`, simply run 

    head -23 myfullbackup.sql | tail -1 > MasterLogFilePos.sql

and the `CHANGE MASTER TO` command will be in it

If you run the mysqldump with

    mysqldump --master-data=2 --flush-logs --single-transaction...

the Master will continue allowing reads and writes to all InnoDB tables.


  [1]: http://dev.mysql.com/doc/refman/5.6/en/mysqldump.html#option_mysqldump_master-data