16.7.7. Using Two Replication Channels
In a more complete example scenario, we envision two replication
channels to provide redundancy and thereby guard against
possible failure of a single replication channel. This requires
a total of four replication servers, two masters for the master
cluster and two slave servers for the slave cluster. For
purposes of the discussion that follows, we assume that unique
identifiers are assigned as shown here:
Setting up replication with two channels is not radically
different from setting up a single replication channel. First,
the mysqld processes for the primary and
secondary replication masters must be started, followed by those
for the primary and secondary slaves. Then the replication
processes may be initiated by issuing the START
SLAVE statement on each of the slaves. The commands
and the order in which they need to be issued are shown here:
-
Start the primary replication master:
shellM> mysqld --ndbcluster --server-id=1 \
--log-bin --binlog-format=row &
-
Start the secondary replication master:
shellM'> mysqld --ndbcluster --server-id=2 \
--log-bin --binlog-format=row &
-
Start the primary replication slave server:
shellS> mysqld --ndbcluster --server-id=3 \
--skip-slave-start &
-
Start the secondary replication slave:
shellS'> mysqld --ndbcluster --server-id=4 \
--skip-slave-start &
-
Finally, commence replication on the primary channel by
executing the START SLAVE statement on
the primary slave as shown here:
mysqlS> START SLAVE;
As mentioned previously, it is not necessary to enable binary
logging on replication slaves.
