MySQL双主（主主）架构方案思路是:

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MySQL双主（主主）架构方案思路是:

1.两台mysql都可读写，互为主备，默认只使用一台（masterA）负责数据的写入，另一台（masterB）备用；

2.masterA是masterB的主库，masterB又是masterA的主库，它们互为主从；

3.两台主库之间做高可用,可以采用keepalived等方案（使用VIP对外提供服务）；

4.所有提供服务的从服务器与masterB进行主从同步（双主多从）;

5.建议采用高可用策略的时候，masterA或masterB均不因宕机恢复后而抢占VIP（非抢占模式）；

这样做可以在一定程度上保证主库的高可用,在一台主库down掉之后,可以在极短的时间内切换到另一台主库上（尽可能减少主库宕机对业务造成的影响），减少了主从同步给线上主库带来的压力；

但是也有几个不足的地方:

1.masterB可能会一直处于空闲状态（可以用它当从库，负责部分查询）；

2.主库后面提供服务的从库要等masterB先同步完了数据后才能去masterB上去同步数据，这样可能会造成一定程度的同步延时；

架构的简易图如下:

主主环境（这里只介绍2台主的配置方案）:

1.CentOS 6.8 64位 2台：masterA（192.168.10.11），masterB（192.168.10.12）

2.官方Mysql5.6版本

搭建过程：

1.安装MySQL服务（建议源码安装）

1.1 yum安装依赖包

yum -y install make gcc gcc-c++ ncurses-devel bison openssl-devel

1.2 添加MySQL所需要的用户和组

groupadd -g 27 mysql

adduser -u 27 -g mysql -s /sbin/nologin mysql

1.3 下载MySQL源码包

mkdir -p /data/packages/src

cd /data/packages/

wget http://distfiles.macports.org/cmake/cmake-3.2.3.tar.gz

wget http://dev.mysql.com/get/Downloads/MySQL-5.6/mysql-5.6.34.tar.gz

1.4 创建mysql数据目录

mkdir -p /usr/local/mysql/data

1.5 解压编译安装cmake、MySQL

cd /data/packages/src

tar -zxvf ../cmake-3.2.3.tar.gz

cd cmake-3.2.3/

./bootstrap

gmake

make install

cd ../

tar xf mysql-5.6.34.tar.gz

cd mysql-5.6.34

cmake . -DCMAKE_INSTALL_PREFIX=/usr/local/mysql -DSYSCONFDIR=/etc \

-DWITH_SSL=bundled -DDEFAULT_CHARSET=utf8 -DDEFAULT_COLLATION=utf8_general_ci \

-DWITH_INNOBASE_STORAGE_ENGINE=1 -DWITH_MYISAM_STORAGE_ENGINE=1 \

-DMYSQL_TCP_PORT=3306 -DMYSQL_UNIX_ADDR=/tmp/mysql.sock \

-DMYSQL_DATADIR=/usr/local/mysql/data

make && make install

1.6 添加开机启动脚本

cp support-files/mysql.server /etc/rc.d/init.d/mysqld

1.7 添加masterA配置文件/etc/my.cnf

[client]

port = 3306

socket = /tmp/mysql.sock

[mysqld]

basedir = /usr/local/mysql

port = 3306

socket = /tmp/mysql.sock

datadir = /usr/local/mysql/data

pid-file = /usr/local/mysql/data/mysql.pid

log-error = /usr/local/mysql/data/mysql.err

server-id = 1

auto_increment_offset = 1

auto_increment_increment = 2 #奇数ID

log-bin = mysql-bin #打开二进制功能,MASTER主服务器必须打开此项

binlog-format=ROW

binlog-row-p_w_picpath=minimal

log-slave-updates=true

gtid-mode=on

enforce-gtid-consistency=true

master-info-repository=TABLE

relay-log-info-repository=TABLE

sync-master-info=1

slave-parallel-workers=0

sync_binlog=0

binlog-checksum=CRC32

master-verify-checksum=1

slave-sql-verify-checksum=1

binlog-rows-query-log_events=1

#expire_logs_days=5

max_binlog_size=1024M #binlog单文件最大值

replicate-ignore-db = mysql #忽略不同步主从的数据库

replicate-ignore-db = information_schema

replicate-ignore-db = performance_schema

replicate-ignore-db = test

replicate-ignore-db = zabbix

max_connections = 3000

max_connect_errors = 30

skip-character-set-client-handshake #忽略应用程序想要设置的其他字符集

init-connect='SET NAMES utf8' #连接时执行的SQL

character-set-server=utf8 #服务端默认字符集

wait_timeout=1800 #请求的最大连接时间

interactive_timeout=1800 #和上一参数同时修改才会生效

sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES #sql模式

max_allowed_packet = 10M

bulk_insert_buffer_size = 8M

query_cache_type = 1

query_cache_size = 128M

query_cache_limit = 4M

key_buffer_size = 256M

read_buffer_size = 16K

skip-name-resolve

slow_query_log=1

long_query_time = 6

slow_query_log_file=slow-query.log

innodb_flush_log_at_trx_commit = 2

innodb_log_buffer_size = 16M

[mysql]

no-auto-rehash

[myisamchk]

key_buffer_size = 20M

sort_buffer_size = 20M

read_buffer = 2M

write_buffer = 2M

[mysqlhotcopy]

interactive-timeout

[mysqldump]

quick

max_allowed_packet = 16M

[mysqld_safe]

1.8 特别参数说明

log-slave-updates = true #将复制事件写入binlog,一台服务器既做主库又做从库此选项必须要开启

#masterA自增长ID

auto_increment_offset = 1

auto_increment_increment = 2 #奇数ID

#masterB自增加ID

auto_increment_offset = 2

auto_increment_increment = 2 #偶数ID

1.9 添加masterB配置文件/etc/my.cnf

[client]

port = 3306

socket = /tmp/mysql.sock

[mysqld]

basedir = /usr/local/mysql

port = 3306

socket = /tmp/mysql.sock

datadir = /usr/local/mysql/data

pid-file = /usr/local/mysql/data/mysql.pid

log-error = /usr/local/mysql/data/mysql.err

server-id = 2

auto_increment_offset = 2

auto_increment_increment = 2 #偶数ID

log-bin = mysql-bin #打开二进制功能,MASTER主服务器必须打开此项

binlog-format=ROW

binlog-row-p_w_picpath=minimal

log-slave-updates=true

gtid-mode=on

enforce-gtid-consistency=true

master-info-repository=TABLE

relay-log-info-repository=TABLE

sync-master-info=1

slave-parallel-workers=0

sync_binlog=0

binlog-checksum=CRC32

master-verify-checksum=1

slave-sql-verify-checksum=1

binlog-rows-query-log_events=1

#expire_logs_days=5

max_binlog_size=1024M #binlog单文件最大值

replicate-ignore-db = mysql #忽略不同步主从的数据库

replicate-ignore-db = information_schema

replicate-ignore-db = performance_schema

replicate-ignore-db = test

replicate-ignore-db = zabbix

max_connections = 3000

max_connect_errors = 30

skip-character-set-client-handshake #忽略应用程序想要设置的其他字符集

init-connect='SET NAMES utf8' #连接时执行的SQL

character-set-server=utf8 #服务端默认字符集

wait_timeout=1800 #请求的最大连接时间

interactive_timeout=1800 #和上一参数同时修改才会生效

sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES #sql模式

max_allowed_packet = 10M

bulk_insert_buffer_size = 8M

query_cache_type = 1

query_cache_size = 128M

query_cache_limit = 4M

key_buffer_size = 256M

read_buffer_size = 16K

skip-name-resolve

slow_query_log=1

long_query_time = 6

slow_query_log_file=slow-query.log

innodb_flush_log_at_trx_commit = 2

innodb_log_buffer_size = 16M

[mysql]

no-auto-rehash

[myisamchk]

key_buffer_size = 20M

sort_buffer_size = 20M

read_buffer = 2M

write_buffer = 2M

[mysqlhotcopy]

interactive-timeout

[mysqldump]

quick

max_allowed_packet = 16M

[mysqld_safe]

1.10 初始化MySQL

cd /usr/local/mysql

scripts/mysql_install_db --user=mysql

1.11 为启动脚本赋予可执行权限并启动MySQL

chmod +x /etc/rc.d/init.d/mysqld

/etc/init.d/mysqld start

2. 配置主从同步

2.1 添加主从同步账户

masterA上：

mysql> grant replication slave on *.* to 'repl'@'192.168.10.12' identified by '123456';

mysql> flush privileges;

masterB上：

mysql> grant replication slave on *.* to 'repl'@'192.168.10.11' identified by '123456';

mysql> flush privileges;

2.2 查看主库的状态

masterA上：

mysql> show master status;

+------------------+----------+--------------+------------------+-------------------+

+------------------+----------+--------------+------------------+-------------------+

| mysql-bin.000003 | 120 | | | |

+------------------+----------+--------------+------------------+-------------------+

1 row in set (0.00 sec)

masterB上

mysql> show master status;

+------------------+----------+--------------+------------------+-------------------+

+------------------+----------+--------------+------------------+-------------------+

| mysql-bin.000003 | 437 | | | |

+------------------+----------+--------------+------------------+-------------------+

1 row in set (0.00 sec)

2.3 配置同步信息：

masterA上：

mysql> change master to master_host='192.168.10.12',master_port=3306,master_user='repl',master_password='123456',master_log_file='mysql-bin.000003',master_log_pos=437;

mysql> start slave;

mysql> show slave status\G;

显示有如下状态则正常：

Slave_IO_Running: Yes

Slave_SQL_Running: Yes

masterB上：

#本人是测试环境，可以保证没数据写入，否则需要的步骤是：先masterA锁表-->masterA备份数据-->masterA解锁表 -->masterB导入数据-->masterB设置主从-->查看主从

mysql> change master to master_host='192.168.10.11',master_port=3306,master_user='repl',master_password='123456',master_log_file='mysql-bin.000003',master_log_pos=120;

start slave;

mysql> show slave status\G;

显示有如下状态则正常：

Slave_IO_Running: Yes

Slave_SQL_Running: Yes

3.测试主从同步

3.1 在masterA上创建一个数据库测试同步效果