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Switching Masters During Failover

There is currently no official solution for providing failover between master and slaves in the event

of a failure. With the currently available features, you would have to set up a master and a slave (or

several slaves), and to wrlte a script that monitors the master to check whether It is up. Then instruct

your applications and the slaves to change master in case of failure.

Remember that you can tell a slave to change its master at any time, using the

CHANGE MASTER TO

statement. The slave will not check whether the databases on the master are compatible with the

slave, it will just start reading and executing events from the specified binary log coordinates on the

new master. In a failover situation, all the servers in the group are typically executing the same events

from the same binary log file, so changing the source of the events should not affect the database

structure or integrity providing you are careful.

Run your slaves with the —log-bin [2039] option and without —log-slave-updates [2004], In

this way, the slave is ready to become a master as soon as you issue STOP SLAVE; RESET MASTER,

and CHANGE MASTER TO statement on the other slaves. For example, assume that you have the

structure shown in Figurę 16.4, “Redundancy Using Replication, Initial Structure".