Preparing the NDB Cluster for replication consists of the following steps:
Check all MySQL servers for version compatibility (see Section 8.2, “General Requirements for NDB Cluster Replication”).
Create a replication account on the source Cluster with the appropriate privileges, using the following two SQL statements:
mysqlS> CREATE USER 'replica_user'@'replica_host' -> IDENTIFIED BY 'replica_password'; mysqlS> GRANT REPLICATION SLAVE ON *.* -> TO 'replica_user'@'replica_host';
In the previous statement,
replica_useris the replication account user name,
replica_hostis the host name or IP address of the replica, and
replica_passwordis the password to assign to this account.
mysqlS> CREATE USER 'myreplica'@'replica-host' -> IDENTIFIED BY '53cr37'; mysqlS> GRANT REPLICATION SLAVE ON *.* -> TO 'myreplica'@'replica-host';
For security reasons, it is preferable to use a unique user account—not employed for any other purpose—for the replication account.
Set up the replica to use the source. Using the mysql client, this can be accomplished with the
CHANGE REPLICATION SOURCE TOstatement (from MySQL 8.0.23) or
CHANGE MASTER TOstatement (before MySQL 8.0.23):
mysqlR> CHANGE MASTER TO -> MASTER_HOST='source_host', -> MASTER_PORT=source_port, -> MASTER_USER='replica_user', -> MASTER_PASSWORD='replica_password'; Or from MySQL 8.0.23: mysqlR> CHANGE REPLICATION SOURCE TO -> SOURCE_HOST='source_host', -> SOURCE_PORT=source_port, -> SOURCE_USER='replica_user', -> SOURCE_PASSWORD='replica_password';
In the previous statement,
source_hostis the host name or IP address of the replication source,
source_portis the port for the replica to use when connecting to the source,
replica_useris the user name set up for the replica on the source, and
replica_passwordis the password set for that user account in the previous step.
For example, to tell the replica to use the MySQL server whose host name is
rep-sourcewith the replication account created in the previous step, use the following statement:
mysqlR> CHANGE MASTER TO -> MASTER_HOST='rep-source', -> MASTER_PORT=3306, -> MASTER_USER='myreplica', -> MASTER_PASSWORD='53cr37'; Or from MySQL 8.0.23: mysqlR> CHANGE REPLICATION SOURCE TO -> SOURCE_HOST='rep-source', -> SOURCE_PORT=3306, -> SOURCE_USER='myreplica', -> SOURCE_PASSWORD='53cr37';
For a complete list of options that can be used with this statement, see CHANGE MASTER TO Statement.
To provide replication backup capability, you also need to add an
--ndb-connectstringoption to the replica's
my.cnffile prior to starting the replication process. See Section 8.9, “NDB Cluster Backups With NDB Cluster Replication”, for details.
For additional options that can be set in
my.cnffor replicas, see Replication and Binary Logging Options and Variables.
If the source cluster is already in use, you can create a backup of the source and load this onto the replica to cut down on the amount of time required for the replica to synchronize itself with the source. If the replica is also running NDB Cluster, this can be accomplished using the backup and restore procedure described in Section 8.9, “NDB Cluster Backups With NDB Cluster Replication”.
In the event that you are not using NDB Cluster on the replica, you can create a backup with this command on the source:
shellS> mysqldump --master-data=1
Then import the resulting data dump onto the replica by copying the dump file over to it. After this, you can use the mysql client to import the data from the dumpfile into the replica database as shown here, where
dump_fileis the name of the file that was generated using mysqldump on the source, and
db_nameis the name of the database to be replicated:
shellR> mysql -u root -p db_name < dump_file
For a complete list of options to use with mysqldump, see mysqldump — A Database Backup Program.Note
If you copy the data to the replica in this fashion, make sure that you stop the replica from trying to connect to the source to begin replicating before all the data has been loaded. You can do this by starting the replica with the
--skip-slave-startoption on the command line, by including
skip-slave-startin the replica's
my.cnffile, or from MySQL 8.0.24, by setting the
skip_slave_startsystem variable. Once the data loading has completed, follow the additional steps outlined in the next two sections.
Ensure that each MySQL server acting as a replication source is assigned a unique server ID, and has binary logging enabled, using the row-based format. (See Replication Formats.) In addition, we recommend enabling the
slave_allow_batchingsystem variable, and possibly increasing the values used with the
--ndb-blob-write-batch-bytesoptions as well. All of these options can be set either in the source server's
my.cnffile, or on the command line when starting the source mysqld process. See Section 8.6, “Starting NDB Cluster Replication (Single Replication Channel)”, for more information.