MariaDB – Master-Master Replication Setup

mariadbmaster-master-replicationMySQLreplication

I have a nagios application running on 2 servers, i am planning to have have master-master replication for HA. for master-slave replication, slave should be read-only. in this manner is there any pre-req for master-master replication. while doing master-master replication i ran into a lot of duplicate as both the databases are auto-increment on their own and trying to replicate each other.

can some one please help to resolve the issue.

Thanks,

Best Answer

To avoid the issue with duplicate keys when using auto_increment PKs, you need to configure the system variables auto_increment_increment and auto_increment_offset.

From the MariaDB Knowledgebase: AUTO_INCREMENT:

To make master-master or Galera safe to use AUTO_INCREMENT one should use the system variables auto_increment_increment and auto_increment_offset to generate unique values for each server.

So in other words, with two masters: On master1 set auto_increment_increment=2 and auto_increment_offset=1, and on master2 set auto_increment_increment=2 and auto_increment_offset=2.

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MySQL – Master-Master Permission Replication Issue

Your grants are not replicating because you have an (unnecessary) replication filter on INFORMATION_SCHEMA. There is no reason to exclude this, as it is not replicated anyhow. When replication filters are in place, you have to USE a database or your statements are not replicated.

For example...not replicated

Grant all privileges on *.* to foo@localhost identified by 'bar';

This is replicated...

USE anydb
Grant all privileges on *.* to foo@localhost identified by 'bar';

....but instead, just remove that replication filter.

MySQL Master-Slave Replication Cross Database

I addressed something like back on June 14, 2012 : Configured MySQL replication but its not working

The basic problem may be the queries you are using

If you have a query that looks like this

INSERT INTO db1.tb SELECT * FROM db2.tb;

You could be potentially blocking queries of this nature

Queries like this:

USE db1
INSERT INTO tb SELECT * FROM db2.tb;

should work if you have replicate-do-db=db1 and Replicate-wild-do-table=db.%

To be sure, check out the replication filtering rules to make sure your queries are allowing your current settings to work on the Slave.

According to the replication filtering rules

To make it easier to determine what effect an option set will have, it is recommended that you avoid mixing “do” and “ignore” options, or wildcard and nonwildcard options. An example of the latter that may have unintended effects is the use of --replicate-do-db and --replicate-wild-do-table together, where --replicate-wild-do-table uses a pattern for the database name that matches the name given for --replicate-do-db. Suppose a replication slave is started with --replicate-do-db=dbx --replicate-wild-do-table=db%.t1. Then, suppose that on the master, you issue the statement CREATE DATABASE dbx. Although you might expect it, this statement is not replicated because it does not reference a table named t1.

Perhaps you need to get rid of one of those rules on the Slave and restart mysql on the Slave.

Best Answer

Related Solutions

MySQL – Master-Master Permission Replication Issue

MySQL Master-Slave Replication Cross Database

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