MySQL 高可用:主从配置或主主(双主)配置

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mysql 的主从复制可以实现mysql的多种高可用性,如数据库的读写分离 ,在线热备,负载均衡,数据分布 等。


mysql 主从同步原理:

1.  master 将操作记录到二进制日志(binary log)中;

2.  slave IO 线程 将master的binary log events读写到它的中继日志(relay log);

3.  slave SQL进程读取中继日志,将重做记录数据到数据库中。


下面配置:【主从复制】


MySQL Version : 5.6.22
主库:centos152 / 192.168.1.152
从库:centos153 / 192.168.1.153


配置 mysql 文件:

【centos152 主库】
[root@centos152 ~]# vi /etc/my.cnf
[mysqld]
basedir =/usr/local/mysql
datadir =/usr/local/mysql/data
port = 3306
server_id = 1
log-bin= mysql-bin
binlog_format = mixed

read-only=0
#binlog-do-db=test
binlog-ignore-db=mysql
binlog-ignore-db=information_schema
binlog-ignore-db=performance_schema
auto-increment-offset=1
auto-increment-increment=2

#添加后重启mysql服务
[root@centos152 ~]# service mysqld restart


【centos153 从库】
[root@centos153 ~]# vi /etc/my.cnf
[mysqld]
basedir =/usr/local/mysql
datadir =/usr/local/mysql/data
port = 3306
server_id = 2
log-bin= mysql-bin
binlog_format = mixed

read-only=0
#replicate-do-db=test
replicate-ignore-db=mysql
replicate-ignore-db=information_schema
replicate-ignore-db=performance_schema
relay_log=mysql-relay-bin
log-slave-updates=on
#auto-increment-offset=2
#auto-increment-increment=2


#添加后重启mysql服务
[root@centos153 ~]# service mysqld restart


说明:

log-bin :需要启用二进制日志
server_id : 用于标识不同的数据库服务器

binlog-do-db : 需要记录到二进制日志的数据库
binlog-ignore-db : 忽略记录二进制日志的数据库
auto-increment-offset :该服务器自增列的初始值。
auto-increment-increment :该服务器自增列增量。

replicate-do-db :指定复制的数据库
replicate-ignore-db :不复制的数据库
relay_log :从库的中继日志,主库日志写到中继日志,中继日志再重做到从库。
log-slave-updates :该从库是否写入二进制日志,如果需要成为多主则可启用。只读可以不需要。

如果为多主的话注意设置 auto-increment-offset 和 auto-increment-increment
如上面为双主的设置:
服务器 152 自增列显示为:1,3,5,7,……(offset=1,increment=2)
服务器 153 自增列显示为:2,4,6,8,……(offset=2,increment=2)


注意:文字图片来自《高性能 mysql》:



#在 [root@centos152 ~] 操作几笔数据后,数据有些变化。

mysql> flush logs;mysql> show master status;+------------------+----------+--------------+---------------------------------------------+-------------------+| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB                            | Executed_Gtid_Set |+------------------+----------+--------------+---------------------------------------------+-------------------+| mysql-bin.000006 |      120 |              | mysql,information_schema,performance_schema |                   |+------------------+----------+--------------+---------------------------------------------+-------------------+

File :当前正在记录的二进制日志文件
Position :记录偏移量,日志 mysql-bin.000006 所记录到的位置。
Binlog_Do_DB :要记录日志的数据库
Binlog_Ignore_DB :不记录日志的数据库
Executed_Gtid_Set :已执行的事务ID


二进制日志情况:

mysql> show variables like '%log_bin%';+---------------------------------+---------------------------------------+| Variable_name                   | Value                                 |+---------------------------------+---------------------------------------+| log_bin                         | ON                                    || log_bin_basename                | /usr/local/mysql/data/mysql-bin       || log_bin_index                   | /usr/local/mysql/data/mysql-bin.index || log_bin_trust_function_creators | OFF                                   || log_bin_use_v1_row_events       | OFF                                   || sql_log_bin                     | ON                                    |+---------------------------------+---------------------------------------+

日志位置:

[root@centos152 ~]# ll /usr/local/mysql/data/mysql-bin*-rw-rw---- 1 mysql mysql 701 10-15 20:30 /usr/local/mysql/data/mysql-bin.000001-rw-rw---- 1 mysql mysql 167 10-15 20:58 /usr/local/mysql/data/mysql-bin.000002-rw-rw---- 1 mysql mysql 167 10-15 21:02 /usr/local/mysql/data/mysql-bin.000003-rw-rw---- 1 mysql mysql 167 10-15 21:02 /usr/local/mysql/data/mysql-bin.000004-rw-rw---- 1 mysql mysql 581 10-18 22:42 /usr/local/mysql/data/mysql-bin.000005-rw-rw---- 1 mysql mysql 120 10-18 22:43 /usr/local/mysql/data/mysql-bin.000006-rw-rw---- 1 mysql mysql 114 10-18 22:43 /usr/local/mysql/data/mysql-bin.index

#现在禁止操作主数据库!防止日志有变化,保证主从数据初始状态一致!
mysql> flush tables with read lock;

备份主库(执行以下一行脚本即可)
[root@centos152 ~]# mysqldump -u root -p test -F > /tmp/test_backup_`date +%Y_%m_%d_%H_%M_%S`.sql[root@centos152 ~]# mysqldump -u root -p --databases test --lock-all-tables --flush-logs> /tmp/test_backup_`date +%Y_%m_%d_%H_%M_%S`.sql

查看当前日志记录的位置:

mysql> show master status \G;*************************** 1. row ***************************             File: mysql-bin.000009         Position: 120     Binlog_Do_DB:  Binlog_Ignore_DB: mysql,information_schema,performance_schemaExecuted_Gtid_Set: 1 row in set (0.00 sec)

备份完后,可以解锁了

mysql> unlock tables;

在主服务器拷贝备份到从服务器:

[root@centos152 ~]# scp -r /tmp/test_backup_2015_10_18_23_33_30.sql root@192.168.1.153:/tmp#不行则先关闭主从服务器防火墙/etc/init.d/iptables status/etc/init.d/iptables stop

在从库中还原数据库:

[root@centos153 ~]# mysql -u root -p test< /tmp/test_backup_2015_10_18_23_33_30.sql

主库创建用于连接到本地的用户:

[root@centos152 ~]# grant replication slave on *.* to 'repl_user'@'192.168.1.153' identified by 'slave@153';

在从库中连接到主库:

mysql> CHANGE MASTER TO        MASTER_HOST='192.168.1.152',        MASTER_USER='repl_user',        MASTER_PASSWORD='slave@153',        MASTER_LOG_FILE='mysql-bin.000009',        MASTER_LOG_POS=120;

重启从库mysql服务
[root@centos153 ~]# service mysqld restart


查看从库同步信息:

mysql> show slave status \G;*************************** 1. row ***************************               Slave_IO_State: Waiting for master to send event                  Master_Host: 192.168.1.152                  Master_User: repl_user                  Master_Port: 3306                Connect_Retry: 60              Master_Log_File: mysql-bin.000009          Read_Master_Log_Pos: 120               Relay_Log_File: mysql-relay-bin.000003                Relay_Log_Pos: 283        Relay_Master_Log_File: mysql-bin.000009             Slave_IO_Running: Yes            Slave_SQL_Running: Yes              Replicate_Do_DB:           Replicate_Ignore_DB: mysql,information_schema,performance_schema

可以看到, IO读写线程 Slave_IO_Running 和 SQL重做线程Slave_SQL_Running 都为 yes,表示正常执行!


现在测试同步情况:

#主库创建测试表create table tabdemo( id int primary key auto_increment,value int default 0) auto_increment= 1 engine=innodb default charset=utf8; insert into tabdemo(value) values(1),(1),(1),(1),(1);select * from tabdemo;+----+-------+| id | value |+----+-------+|  1 |     1 ||  3 |     1 ||  5 |     1 ||  7 |     1 ||  9 |     1 |+----+-------+

主库操作,主库和从库都有数据了!id 编号与上面所说的一样!~现在主从复制已经配置成功!~


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下面配置:【主主复制】


更改配置文件:

【centos152 原主库】更改配置文件
[root@centos152 ~]# vi /etc/my.cnf
[mysqld]
basedir =/usr/local/mysql
datadir =/usr/local/mysql/data
port = 3306
server_id = 1
log-bin= mysql-bin
binlog_format = mixed

read-only=0
#binlog-do-db=test
binlog-ignore-db=mysql
binlog-ignore-db=information_schema
binlog-ignore-db=performance_schema
auto-increment-offset=1
auto-increment-increment=2

#主主复制的从库设置(新增)
#replicate-do-db=test
replicate-ignore-db=mysql
replicate-ignore-db=information_schema
replicate-ignore-db=performance_schema
relay_log=mysql-relay-bin
log-slave-updates=on


【centos153 原从库】更改配置文件
[root@centos153 ~]# vi /etc/my.cnf
[mysqld]
basedir =/usr/local/mysql
datadir =/usr/local/mysql/data
port = 3306
server_id = 2
log-bin= mysql-bin
binlog_format = mixed

read-only=0
#replicate-do-db=test
replicate-ignore-db=mysql
replicate-ignore-db=information_schema
replicate-ignore-db=performance_schema
relay_log=mysql-relay-bin
log-slave-updates=on

#主主复制的主库设置(新增)
#binlog-do-db=test
binlog-ignore-db=mysql
binlog-ignore-db=information_schema
binlog-ignore-db=performance_schema
auto-increment-offset=2
auto-increment-increment=2


添加后都重启mysql服务:
[root@centos153 ~]# service mysqld restart


原从库(153)中创建用于连接的用户:

[root@centos153 ~]# grant replication slave on *.* to 'repl_user'@'192.168.1.152' identified by 'slave@152';

原从库(153)查看当前日志记录的位置:

mysql> show master status \G;*************************** 1. row ***************************             File: mysql-bin.000005         Position: 120     Binlog_Do_DB:  Binlog_Ignore_DB: mysql,information_schema,performance_schemaExecuted_Gtid_Set: 1 row in set (0.00 sec)

在主库(152)中连接到原从库(153),之前的从库现在也将是主库:

mysql> CHANGE MASTER TO        MASTER_HOST='192.168.1.153',        MASTER_USER='repl_user',        MASTER_PASSWORD='slave@152',        MASTER_LOG_FILE='mysql-bin.000005',        MASTER_LOG_POS=120;

重启从库(152)mysql服务:
[root@centos152 ~]# service mysqld restart


查看从库(152)的同步信息:

mysql> show slave status \G;*************************** 1. row ***************************               Slave_IO_State: Waiting for master to send event                  Master_Host: 192.168.1.153                  Master_User: repl_user                  Master_Port: 3306                Connect_Retry: 60              Master_Log_File: mysql-bin.000005          Read_Master_Log_Pos: 120               Relay_Log_File: mysql-relay-bin.000003                Relay_Log_Pos: 283        Relay_Master_Log_File: mysql-bin.000005             Slave_IO_Running: Yes            Slave_SQL_Running: Yes              Replicate_Do_DB:           Replicate_Ignore_DB: mysql,information_schema,performance_schema



现在已经配置好双主了!现在相互在两个数据库中都操作数据:

#当前在原来的从库(153)操作数据。insert into tabdemo(value) values(2),(2),(2),(2),(2);#数据同步正常了!select * from tabdemo;+----+-------+| id | value |+----+-------+|  1 |     1 ||  3 |     1 ||  5 |     1 ||  7 |     1 ||  9 |     1 || 10 |     2 || 12 |     2 || 14 |     2 || 16 |     2 || 18 |     2 |+----+-------+在原来的主库(152)操作数据。insert into tabdemo(value) values(3),(3),(3),(3),(3);#也正常!select * from tabdemo;+----+-------+| id | value |+----+-------+|  1 |     1 ||  3 |     1 ||  5 |     1 ||  7 |     1 ||  9 |     1 || 10 |     2 || 12 |     2 || 14 |     2 || 16 |     2 || 18 |     2 || 19 |     3 || 21 |     3 || 23 |     3 || 25 |     3 || 27 |     3 |+----+-------+

至此,测试完毕!~注意参考:学一点 mysql 双机异地热备份—-mysql主从,主主备份原理及实践


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