Mysql双主实战

参考：
http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html
http://blog.chinaunix.net/uid-26446098-id-3267556.html

一、 环境
master1 192.168.11.100
CentOS release 6.2

master2 192.168.11.110
CentOS release 6.2

二、软件安装
yum -y install mysql-server perl lua

三、配置
1、基本目录准备
两台服务器分别执行
数据目录和binlog目录
[root@master1 ~]# mkdir -p /data/mysql/binlogs && chown -R mysql.mysql /data/mysql/
日志目录
[root@master1 ~]# mkdir /data/logs/mysql/ && chown -R mysql.mysql /data/logs/mysql/
binlog目录

2、配置
两台服务器分别执行
[root@master1 ~]# egrep -v '^#|^$' /usr/share/doc/mysql-server-5.1.69/my-huge.cnf > /etc/my.cnf
[root@master2 ~]# egrep -v '^#|^$' /usr/share/doc/mysql-server-5.1.69/my-huge.cnf > /etc/my.cnf
master1配置文件
[root@master1 ~]# cat /etc/my.cnf
### NO-3306 Master ###
[mysqld]
datadir = /data/mysql/
port = 3306
socket = /data/mysql/mysql.sock
pid-file = /data/mysql/mysql.pid

#log
log-error = /data/logs/mysql/3306_error.log
long_query_time = 2
slow-query-log-file = /data/logs/mysql/3306_slow.log

log-bin = binlogs/mysql-bin
binlog_format = ROW
relay-log = binlogs/mysql-relay-bin

#data
innodb_data_file_path = ibdata1:500M;ibdata2:500M:autoextend
innodb_buffer_pool_size = 256M
innodb_additional_mem_pool_size = 50M
innodb_log_file_size = 256M
innodb_open_files = 500
back_log = 1000
join_buffer_size = 8M
query_cache_size = 16M
read_buffer_size = 4M
sort_buffer_size = 8M
innodb_thread_concurrency = 8

character_set_server = utf8
init-connect = 'SET NAMES utf8'

replicate-ignore-db = mysql
replicate-ignore-db = test
replicate-ignore-db = performance_schema

skip-name-resolve

skip-external-locking
slave-skip-errors = all
server-id = 33061
log-slave-updates = 1

[mysqldump]
quick
max_allowed_packet = 16M
[mysql]
no-auto-rehash

[myisamchk]
key_buffer_size = 256M
sort_buffer_size = 256M
read_buffer = 2M
write_buffer = 2M

[mysqlhotcopy]
interactive-timeout

master2 配置文件 和master一样 不过是serverid增加1

### NO-3306 Master backup ###
[mysqld]
datadir = /data/mysql/
port = 3306
socket = /data/mysql/mysql.sock
pid-file = /data/mysql/mysql.pid

#log
log-error = /data/logs/mysql/3306_error.log
long_query_time = 2
slow-query-log-file = /data/logs/mysql/3306_slow.log

log-bin = binlogs/mysql-bin
binlog_format = ROW
relay-log = binlogs/mysql-relay-bin

#data
innodb_data_file_path = ibdata1:500M;ibdata2:500M:autoextend
innodb_buffer_pool_size = 256M
innodb_additional_mem_pool_size = 50M
innodb_log_file_size = 256M
innodb_open_files = 500
back_log = 1000
join_buffer_size = 8M
query_cache_size = 16M
read_buffer_size = 4M
sort_buffer_size = 8M
innodb_thread_concurrency = 8

character_set_server = utf8
init-connect = 'SET NAMES utf8'

replicate-ignore-db = mysql
replicate-ignore-db = test
replicate-ignore-db = performance_schema

skip-name-resolve
skip-external-locking
slave-skip-errors = all
server-id = 33062
log-slave-updates = 1

[mysqldump]
quick
max_allowed_packet = 16M
[mysql]
no-auto-rehash

[myisamchk]
key_buffer_size = 256M
sort_buffer_size = 256M
read_buffer = 2M
write_buffer = 2M

[mysqlhotcopy]
interactive-timeout

四、初始化数据库并启动
1、初始化
[root@master1 ~]# mysql_install_db --datadir=/data/mysql/ --user=mysql --force
[root@master2 ~]# mysql_install_db --datadir=/data/mysql/ --user=mysql --force

2、启动
[root@master1 ~]# /usr/bin/mysqld_safe --defaults-file=/etc/my.cnf --user=mysql &
[root@master2 ~]# /usr/bin/mysqld_safe --defaults-file=/etc/my.cnf --user=mysql &

3、权限
[root@master1 ~]# mysqladmin -S /data/mysql/mysql.sock -uroot -p password 'password'
Enter password:

[root@master1 ~]# mysql -S /data/mysql/mysql.sock --password=password
复制权限
mysql> grant REPLICATION SLAVE on *.* to 'repl'@'192.168.11.%' identified by 'replpwd';
proxy权限
mysql> grant all on *.* to 'dbproxy'@'192.168.11.%' identified by 'dbproxypwd';

同样的操作在master2上执行一遍

五、同步

同步前再次确认网络连通情况
[root@master1 ~]# telnet 192.168.11.110 3306
[root@master2 ~]# telnet 192.168.11.100 3306
1、master1做主master2做从
[root@master1 ~]# mysql -S /data/mysql/mysql.sock --password=password -e"show master status;"
+------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000004 | 106 | | |
+------------------+----------+--------------+------------------+
mysql> change master to MASTER_HOST='192.168.11.100',MASTER_PORT=3306,MASTER_USER='repl',MASTER_PASSWORD='replpwd',MASTER_LOG_FILE='mysql-bin.000004',MASTER_LOG_POS=106;
Query OK, 0 rows affected (0.03 sec)
mysql> start slave;
Query OK, 0 rows affected (0.01 sec)
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.11.100
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000004
Read_Master_Log_Pos: 106
Relay_Log_File: mysql-relay-bin.000002
Relay_Log_Pos: 251
Relay_Master_Log_File: mysql-bin.000004
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB: mysql,test,performance_schema
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 106
Relay_Log_Space: 406
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
1 row in set (0.00 sec)

2、master2做主master1做从
[root@master2 ~]# mysql -S /data/mysql/mysql.sock --password=password -e"show master status;"
+------------------+----------+--------------+------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000005 | 106 | | |
+------------------+----------+--------------+------------------+

[root@master1 ~]# mysql -S /data/mysql/mysql.sock --password=password
mysql> change master to MASTER_HOST='192.168.11.110',MASTER_PORT=3306,MASTER_USER='repl',MASTER_PASSWORD='replpwd',MASTER_LOG_FILE='mysql-bin.000005',MASTER_LOG_POS=106;
Query OK, 0 rows affected (0.03 sec)
mysql> start slave;
Query OK, 0 rows affected (0.01 sec)

mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.11.110
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000005
Read_Master_Log_Pos: 106
Relay_Log_File: mysql-relay-bin.000002
Relay_Log_Pos: 251
Relay_Master_Log_File: mysql-bin.000005
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB: mysql,test,performance_schema
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 106
Relay_Log_Space: 406
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
1 row in set (0.00 sec)

六、测试
1、验证master1复制到master2
再master1创建库master1和表test_jin测试
[root@master1 ~]# mysql -S /data/mysql/mysql.sock --password=password -e"create database master1;"
[root@master2 ~]# mysql -S /data/mysql/mysql.sock --password=password -e"show databases;" |grep master1
master1
[root@master1 ~]# mysql -S /data/mysql/mysql.sock --password=password -e"create table master1.test_jin (id int(6) not null,name varchar(20) not null);"
[root@master2 ~]# mysql -S /data/mysql/mysql.sock --password=password -e"use master1;show tables;"
+-------------------+
| Tables_in_master1 |
+-------------------+
| test_jin |
+-------------------+
[root@master1 ~]# mysql -S /data/mysql/mysql.sock --password=password -e"insert into master1.test_jin values (100001,'kaijin');"
[root@master2 ~]# mysql -S /data/mysql/mysql.sock --password=password -e"select * from master1.test_jin;"
+--------+--------+
| id | name |
+--------+--------+
| 100001 | kaijin |
+--------+--------

可见从master1复制到master2成功

2、验证master2复制到master1
[root@master2 ~]# mysql -S /data/mysql/mysql.sock --password=password -e"create database master2;"
[root@master1 ~]# mysql -S /data/mysql/mysql.sock --password=password -e"show databases;" |grep master2
master2

[root@master2 ~]# mysql -S /data/mysql/mysql.sock --password=password -e"create table master2.test_master2 (id int(6) not null,name varchar(20) not null);"
[root@master1 ~]# mysql -S /data/mysql/mysql.sock --password=password -e"use master2;show tables;"
+-------------------+
| Tables_in_master2 |
+-------------------+
| test_master2 |
+-------------------+

[root@master2 ~]# mysql -S /data/mysql/mysql.sock --password=password -e"insert into master2.test_master2 values (100002,'master2');"
[root@master1 ~]# mysql -S /data/mysql/mysql.sock --password=password -e"select * from master2.test_master2;"
+--------+---------+
| id | name |
+--------+---------+
| 100002 | master2 |
+--------+---------+

可见
验证master2复制到master1成功

双主相互复制成功

这里也解决了我一个疑问，创建库是否也复制。毫无疑问是复制的，只要记录在binglog里都会复制

七、总结
1、几个重点
1)log_slave_updates
log-slave-updates 默认未开启
log-slave-updates = 1开启
log-slave-updates是为从库的写操作记录binlog
在双主上必须配置。没有有它，双主是配不成的，关于它的详细介绍。在如下网址：
http://dev.mysql.com/doc/refman/5.1/en/replication-options-slave.html#option_mysqld_log-slave-updates
就是可以A -> B -> C，保证A可以作为master，复制到B，B可以作为master，复制到C.所以呢，如果A和B互相的话，就是双主了。
2)binlog_format
binlog_format = ROW
详细介绍binlog_format几种模式的区别，可以参考
http://codejm.iteye.com/blog/1540046

八、未测试部分
1、auto_increment 数据唯一性
测试可以参考：http://www.mysqlops.com/2011/06/07/mysql-replication-data-consistency.html

这里只往其中一个master写数据的保险的方法，如果要同时往两个master都写数据呢？
模拟出现的问题（多主自增长ID重复）
假如我们在master1,master2都建立一张test表，表中有一个auto increment的字段
停掉master1的同步，在master2上对数据表test(存在自增长ID)执行插入操作，返回插入ID为1
然后停掉master2的同步，在master1上对数据表test(存在自增长ID)执行插入操作，返回的插入ID也是1
然后同时启动master1,master2，就会出现主键ID重复

解决方法：
我们只要保证两台服务器上插入的自增长数据不同就可以了
master1增加配置
auto_increment_increment=2
auto_increment_offset=1

master2增加配置
auto_increment_increment=2
auto_increment_offset=2

具体
auto_increment_increment和auto_increment_offset用于主服务器－主服务器（master-to-master）复制
auto_increment_increment的默认值为1。
auto_increment_offset的默认值为1。

mysql> SHOW VARIABLES LIKE 'auto_inc%';
+--------------------------+-------+
| Variable_name | Value |
+--------------------------+-------+
| auto_increment_increment | 1 |
| auto_increment_offset | 1 |
+--------------------------+-------+
2 rows in set (0.01 sec)

auto_increment_offset确定AUTO_INCREMENT列值的起点。影响到在复制设置主可以有多少主服务器(例如将该值设置为10表示设置可以支持10个服务器)

第一个变量名 auto_increment_increment 就是指 字段一次递增多少；
第二个变量名 auto_increment_offset 指 自增字段的起始值。
比如，有个表test，字段id为主键，自增；
如果auto_increment_offset=1 ， 并且auto_increment_increment=1，那么向表中插入第一条数据时，则该条数据的id=1，第二条id=2，第三条id=3以此类推……
如果auto_increment_offset=2 ， 并且auto_increment_increment=10，那么向表中插入第一条数据时，则该条数据的id=2，第二条id=12，第三条id=22以此类推……
注意：如果auto_increment_offset的值大于auto_increment_increment的值，则auto_increment_offset的值被忽略。

在这里设置
auto_increment_increment=2
auto_increment_offset=1
第一条数据为1，第二条3，第三条5

auto_increment_increment=2
auto_increment_offset=2
第一条数据为2，第二条4，第三条6

2、read-only（保证只读）
在第二master上添加次参数
添加上测试一下
read-only默认未开启
read-only = 1 开启测试看看

[root@master2 ~]# kill $(cat /data/mysql/mysql.pid)
[root@master2 ~]#/usr/bin/mysqld_safe --defaults-file=/etc/my.cnf --user=mysql &
[root@master2 ~]# mysqladmin -S /data/mysql/mysql.sock --password=password VARIABLES |grep read_only
| read_only | ON

master2写入数据 看是否同步到master1
[root@master2 ~]# mysql -S /data/mysql/mysql.sock --password=password -e"insert into master2.test_master2 values (100003,'master3');"
[root@master2 ~]# mysql -S /data/mysql/mysql.sock --password=password -e"select * from master2.test_master2;"
+--------+---------+
| id | name |
+--------+---------+
| 100002 | master2 |
| 100003 | master3 |
+--------+---------+
可以写入master2

[root@master1 ~]# mysql -S /data/mysql/mysql.sock --password=password -e"select * from master2.test_master2;"
+--------+---------+
| id | name |
+--------+---------+
| 100002 | master2 |
| 100003 | master3 |
+--------+---------+
也同步过去了
Cause the slave to permit no updates except from slave threads or from users having the SUPER privilege. On a slave server,
this can be useful to ensure that the slave accepts updates only from its master server and not from clients. This variable does not apply to TEMPORARY tables.
官方说明
导致从不允许任何更新，除了从从属线程或具有SUPER权限的用户。从服务器上的，这可能是有用的，以确保只从它的主服务器，而不是从客户的奴隶接受更新。此变量不适临时表。

这个参数不加也不要紧。要使用第二个主，也是在proxy里加入readonly