I'm trying to set up MySQL replication between two servers. This will eventually expand to circular multi-master replication, but I need to get one-way replication between two machines working first. Both sides running version: 5.1.52 Source distribution on Amazon Linux. I'm working with the directions at http://www.howtoforge.com/mysql_master_master_replication My machines are cpu1 and cpu2. On cpu2 (the replication master) /etc/my.cnf contains: [mysqld] datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock user=mysql default-storage-engine=MyISAM # Disabling symbolic-links is recommended to prevent assorted security risks symbolic-links=0 skip-innodb server-id=2 auto_increment_increment=10 auto_increment_offset=2 log-bin binlog-do-db=cphulkd binlog-do-db=cst_accounts binlog-do-db=custom binlog-do-db=iowa binlog-do-db=mcc binlog-do-db=mcc_users binlog-do-db=modsec binlog-do-db=mpi binlog-do-db=mysql binlog-do-db=noc binlog-do-db=online_encoding binlog-do-db=play_details binlog-do-db=ppv binlog-do-db=reporting binlog-do-db=support [mysqld_safe] log-error=/var/log/mysqld.log pid-file=/var/run/mysqld/mysqld.pid On cpu1 (the intended replicaqtion slave) the /etc/my.cnf file contains: [mysqld] datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock user=mysql # Disabling symbolic-links is recommended to prevent assorted security risks symbolic-links=0 default-storage-engine=MyISAM skip-innodb server-id=3 auto-increment-increment=10 auto-increment-offset=3 #master-host=10.2.13.160 master-host=18.104.22.168 master-user=<my replication user name> master-password=<my replication password) master-port=3306 [mysqld_safe] log-error=/var/log/mysqld.log pid-file=/var/run/mysqld/mysqld.pid I stop/start cpu2 and get normal indications in log file. I stop/start cpu1 and the log file contains the following: 110715 16:53:48 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql 110715 16:53:48 [Warning] 'for replication startup options' is deprecated and will be removed in a future release. Please use ''CHANGE MASTER'' instead. 110715 16:53:48 [Note] Plugin 'InnoDB' is disabled. 110715 16:53:48 [Warning] Neither --relay-log nor --relay-log-index were used; so replication may break when this MySQL server acts as a slave and has his hostname changed!! Please use '--relay-log=mysqld-relay-bin' to avoid this problem. 110715 16:53:48 [Note] Event Scheduler: Loaded 0 events 110715 16:53:48 [Note] /usr/libexec/mysqld: ready for connections. Version: '5.1.52' socket: '/var/lib/mysql/mysql.sock' port: 3306 Source distribution 110715 16:53:48 [Note] Slave SQL thread initialized, starting replication in log 'FIRST' at position 106, relay log './mysqld-relay-bin.000011' position: 4 110715 16:53:48 [Note] Slave I/O thread: connected to master 'test@:3306',replication started in log 'FIRST' at position 4 110715 16:53:48 [ERROR] Slave I/O: Fatal error: The slave I/O thread stops because master and slave have equal MySQL server ids; these ids must be different for replication to work (or the --replicate-same-server-id option must be used on slave but this does not always make sense; please check the manual before using it). Error_code: 1593 110715 16:53:48 [Note] Slave I/O thread exiting, read up to log 'FIRST', position 4 The next to last log line is what has me confused. You can clearly see from the my.cnf files above that the master's my.cnf contains "server-id=2" while the slave's my.cnf contains "server-id=3". Any idea what's going on with that error message?