If you want to have a full backup without lock the live database, I will suggest that you start to replicate all information from master server into a slave, and take a full backup right from slave, this way you will hava a consistent backup from master without have to lock or put load on the master database at any moment.
You can look into MySQL Documentation for Replication, I also wrote a post a while ago about how to set up replication, you can have a look here.
Once you have your replication working, you can write a script to stop the slave (this way you will make sure you have a consistent copy of the master data), copy the position that your slave is reading from master (in case you need to restore your database, you can replay the master log from this position) and take the backup, in bash it will look like this:
echo "STOP SLAVE;" | mysql -u $MYSQL_USER -p$MYSQL_PWD
echo "SHOW SLAVE STATUS\G" | mysql -u $MYSQL_USER -p$MYSQL_PWD > $MYSQL_SLAVE_STATUS_FILE
mysqldump -u $MYSQL_USER -p$MYSQL_PWD --all-databases --routines --triggers > $MYSQL_DUMP_FILE
echo "START SLAVE;" | mysql -u $MYSQL_USER -p$MYSQL_PWD
mysql_slave_status you will need to look into 2 variables named
Exec_Master_Log_Pos it will tell you the binary log file and position that you need to start to replay the binary log in case you need to restore this dump.
Other way rather than save the slave position is to add