2.1.1 Setting the Replication Master Configuration

On a replication master, you must enable binary logging and establish a unique server ID. If this has not already been done, a server restart is required.

Binary logging must be enabled on the master because the binary log is the basis for replicating changes from the master to its slaves. If binary logging is not enabled using the log-bin option, replication is not possible.

Each server within a replication group must be configured with a unique server ID. This ID is used to identify individual servers within the group, and must be a positive integer between 1 and (2³²)−1. How you organize and select the numbers is your choice.

To configure the binary log and server ID options, shut down the MySQL server and edit the my.cnf or my.ini file. Within the [mysqld] section of the configuration file, add the log-bin and server-id options. If these options already exist, but are commented out, uncomment the options and alter them according to your needs. For example, to enable binary logging using a log file name prefix of mysql-bin, and configure a server ID of 1, use these lines:

[mysqld]
log-bin=mysql-bin
server-id=1

After making the changes, restart the server.

Note

If you do not set server_id (or set it explicitly to its default value of 0), the master refuses any connections from slaves.

Note

For the greatest possible durability and consistency in a replication setup using InnoDB with transactions, you should use innodb_flush_log_at_trx_commit=1 and sync_binlog=1 in the master my.cnf file.

Note

Ensure that the skip_networking system variable is not enabled on your replication master. If networking has been disabled, the slave can not communicate with the master and replication fails.