MySQL双主（主主）架构方案思路是:
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;
+------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000003 | 120 | | | |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
masterB上
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| 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
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
4 rows in set (0.00 sec)
mysql> create database test01;
Query OK, 1 row affected (0.00 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
| test01 |
+--------------------+
5 rows in set (0.00 sec)
mysql> quit
Bye
[root@masterA data]#
3.2 到masterB查看是否已经同步创建数据库
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
| test01 |
+--------------------+
5 rows in set (0.00 sec)
mysql> quit
Bye
[root@masterB data]#
4. 开启MySQL5.6的GTID功能
masterA和masterB分别执行如下命令：
mysql> stop slave;
Query OK, 0 rows affected (0.00 sec)
mysql> change master to MASTER_AUTO_POSITION=1;
Query OK, 0 rows affected (0.01 sec)
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)
5. 遇到的问题
一种主从报错折腾了我半天：
Last_IO_Errno: 1236
Last_IO_Error: Got fatal error 1236 from master when reading data from binary log: 'Could not open log file'
后面修改主从同步相关 参数，确认原因是my.cnf增加了如下参数：
log-bin = mysql-bin
relay-log = mysql-bin
从正常主主同步时的二进制日志文件显示，有2套二进制日志。因此推断上面2个参数导致不能产生2套二进制文件，故导致二进制文件错乱和丢失。