十五周二次课

17.1mysql主从介绍

17.2准备工作

17.3配置主

17.4配置从

17.5测试主从同步

17.1mysql主从介绍

MySQL主从介绍

MySQL主从又叫做Replication、AB复制。简单讲就是A和B两台机器做主从后，在A上写数据，另外一台B也会跟着写数据，两者数据实时同步的
MySQL主从是基于binlog的，主上须开启binlog才能进行主从。
- binlog，其实就是一个文件，文件里记录了一些日志，文件是二进制文件，无法cat
主从过程大致有3个步骤
- 1）主将更改操作记录到binlog里
- 2）从将主的binlog事件(sql语句)同步到从本机上并记录在relaylog里
  - relaylog，中文叫做中继日志
- 3）从根据relaylog里面的sql语句按顺序执行

mysql主从共有三个线程
- 主上有一个log dump线程，用来和从的I/O线程传递binlog
- 从上有两个线程，其中I/O线程用来同步主的binlog并生成relaylog，另外一个SQL线程用来把relaylog里面的sql语句落地

MySQL主从原理图

输入图片说明

原理很简单：从会把主上的binlog搞到从上来，从再根据这个binlog生成自己的中继日志，然后再根据中继日志执行相应的更改，最终达到两边的数据一致。

mysql主从使用场景：

数据备份，主机器宕机，从机器还能随时对web提供服务；
作为一个从库，读的库，减轻主库的压力，数据备份且可以分担主机器被调用数据时的压力，mysql主从，是有方向性的，写数据，必须从主机器开始，如果不依照原理会导致数据紊乱。

17.2准备工作

mysql安装总结

mysql主从准备工作：
- 准备两台机器，每台机器安装msyql服务，并启动mysql服务
mysql详细安装

1.首先下载二进制免编译的包，下载到/usr/local/src/目录下

2.解压压缩包

3.解压完之后，把解压出来的目录放到 /usr/local/mysql/ 目录下

注意点：
- 首先检查 /usr/local/mysql/ 目录是否存在
- 若是这个目录存在，首先把这个目录改个名字，或者把目录下的内容删除
- 然后把解压出来的目录放到 /usr/local/mysql/ 目录下面
目录内容应该如下

[root@hanfeng ~]# ls /usr/local/mysql
bin      data  include  man     my-new.cnf  README   share      support-files
COPYING  docs  lib      my.cnf  mysql-test  scripts  sql-bench
[root@hanfeng ~]#

4.然后切换到 /usr/local/mysql/ 目录下，进行初始化命令

初始化命令 ./scripts/mysql_install_db --user=mysql --datadir=/data/mysql
- 注意点：
  - 其中的--user=mysql 需要提前创建

5.初始化成功的标志就是两个OK，或者用 echo $? 检查是否初始化成功

6.编辑 /etc/my.cnf 文件——>默认是自带 my.cnf 文件的

在 /etc/my.cnf 文件中
定义 datadir=/data/mysql     
定义 socket=/tmp/mysql.sock

7.拷贝启动脚本

命令 cp /usr/local/mysql/support-files/mysql.server /etc/init.d/mysqld

8.编辑启动脚本

vim /etc/init.d/mysqld //对以下两行进行指定路径

指定basedir的路径 /usr/local/mysql  
指定datadir的路径 /data/mysql

9.之后就可以启动mysql了

命令 /etc/init.d/mysql start

10.如果启动失败，可以去查看错误日志

11.建议：

查看 /data/mysql 目录下的文件，默认属主、属组，如果不是mysql的，启动时会因无法写入数据而不能启动mysql
- 改变属主和属组，命令 chomd mysql:mysql /data/mysql
然后就可以尝试启动，命令 /etc/init.d/mysql start

12.若想开机启动，只需要输入命令

命令 chkconfig mysqld on

17.3 配置主

主从配置 - 主上操作

安装mysql
修改my.cnf，增加server-id=130和log_bin=aminglinux1
修改完配置文件后，启动或者重启mysqld服务
把mysql库备份并恢复成aming库，作为测试数据
mysqldump -uroot mysql > /tmp/mysql.sql
mysql -uroot -e “create database aming”
mysql -uroot aming < /tmp/mysql.sql
创建用作同步数据的用户
grant replication slave on . to 'repl'@slave_ip identified by 'password';
flush tables with read lock;
show master status;

主从配置 - 主上操作

1.在两台机器安装并启动mysql服务后，首先在主上进行操作（主为192.168.23.136，从为192.168.23.130）。

2.修改/etc/my.cnf文件

在配置文件中[mysqld]下添加
- server-id=136,这个id可以自定义，这里根据ip来定义
- log_bin=aminglinux1,打开binlog，名字自定义为aminglinux1,最终结果如下：

[root@localhost ~]# vim /etc/my.cnf

[mysqld]
datadir=/data/mysql
socket=/tmp/mysql.sock
server-id=136
log_bin=aminglinux1
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
# Settings user and group are ignored when systemd is used.
# If you need to run mysqld under a different user or group,
# customize your systemd unit file for mariadb according to the
# instructions in http://fedoraproject.org/wiki/Systemd

[mysqld_safe]
#log-error=/var/log/mariadb/mariadb.log
#pid-file=/var/run/mariadb/mariadb.pid

#
# include all files from the config directory
#
#!includedir /etc/my.cnf.d

保存退出

3.更改完配置以后，需要重启mysql服务。

[root@localhost ~]# /etc/init.d/mysqld restart
Shutting down MySQL... SUCCESS!
Starting MySQL.......... SUCCESS!
[root@localhost ~]#

如果重启过程中出现“Plugin 'FEDERATED' is disabled”错误，删除/data目录下除mysql以外的目录即可

4.查看/data/mysql目录下，会生成一些文件

[root@localhost mysql]# ls -lt /data/mysql
total 110656
-rw-rw---- 1 mysql mysql 120 Jun 17 14:23 aminglinux1.000001
-rw-rw---- 1 mysql mysql 21 Jun 17 14:23 aminglinux1.index
-rw-rw---- 1 mysql mysql 56 Jun 5 10:09 auto.cnf
drwxr-xr-x 2 root root 6 Jun 17 14:31 blog
-rw-rw---- 1 mysql mysql 12582912 Jun 17 14:23 ibdata1
-rw-rw---- 1 mysql mysql 50331648 Jun 17 14:23 ib_logfile0
-rw-rw---- 1 mysql mysql 50331648 Jun 5 10:08 ib_logfile1
-rw-rw---- 1 mysql mysql 36693 Jun 17 14:23 localhost.localdomain.err
-rw-rw---- 1 mysql mysql 5 Jun 17 14:23 localhost.localdomain.pid
drwx------ 2 mysql mysql 4096 Jun 5 10:08 mysql
drwx------ 2 mysql mysql 4096 Jun 17 11:08 mysql2
drwx------ 2 mysql mysql 4096 Jun 5 10:08 performance_schema
drwx------ 2 mysql mysql 6 Jun 5 10:08 test
[root@localhost mysql]#

其中，.index索引页这个文件是必需的
.000001文件是个二进制文件，会持续生成2，3，4等等（这个文件是实现主从复制的根本，没有这个文件根本没法完成主从）

5.测试，准备做一个数据做演示看

6.首先做一个备份

[root@localhost mysql]# mysqldump -uroot -paminglinux blog > /tmp/blog.sql
Warning: Using a password on the command line interface can be insecure.
[root@localhost mysql]#

7.创建一个新的数据库

[root@localhost mysql]# mysql -uroot -paminglinux -e "create database aming"
Warning: Using a password on the command line interface can be insecure.
[root@localhost mysql]#

8.创建好数据库以后，还需要把数据恢复一下，也就是说做的主从，参考对象是aming数据库

[root@localhost mysql]# mysql -uroot -paminglinux aming < /tmp/blog.sql
Warning: Using a password on the command line interface can be insecure.
[root@localhost mysql]#

9.再次查看/data/mysql目录下的文件

[root@localhost mysql]# ls -l /data/mysql
total 110656
drwx------ 2 mysql mysql 20 Jun 17 14:33 aming
-rw-rw---- 1 mysql mysql 217 Jun 17 14:33 aminglinux1.000001
-rw-rw---- 1 mysql mysql 21 Jun 17 14:23 aminglinux1.index
-rw-rw---- 1 mysql mysql 56 Jun 5 10:09 auto.cnf
drwxr-xr-x 2 root root 6 Jun 17 14:31 blog
-rw-rw---- 1 mysql mysql 12582912 Jun 17 14:23 ibdata1
-rw-rw---- 1 mysql mysql 50331648 Jun 17 14:23 ib_logfile0
-rw-rw---- 1 mysql mysql 50331648 Jun 5 10:08 ib_logfile1
-rw-rw---- 1 mysql mysql 36693 Jun 17 14:23 localhost.localdomain.err
-rw-rw---- 1 mysql mysql 5 Jun 17 14:23 localhost.localdomain.pid
drwx------ 2 mysql mysql 4096 Jun 5 10:08 mysql
drwx------ 2 mysql mysql 4096 Jun 17 11:08 mysql2
drwx------ 2 mysql mysql 4096 Jun 5 10:08 performance_schema
drwx------ 2 mysql mysql 6 Jun 5 10:08 test
[root@localhost mysql]#

10.正常情况下，能看到aminglinux1.000001二进制文件是由增加的，增加的大小是和blog库保持一致的，aminglinux1.000001完整地记录了数据库的过程。创建的库，创建的表，以及表里的内容全都有。

11.下面创建主从相互同步用的用户

12.进入mysql里面去

[root@localhost mysql]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.6.35-log MySQL Community Server (GPL)

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql>

13.创建用户

grant制定权限，replication slave权限
针对repl这个用户
针对从的ip制定来源（若是写所有的ip会很危险）

mysql> grant replication slave on *.* to 'repl'@'192.168.23.130' identified by 'aminglinux111';
Query OK, 0 rows affected (0.00 sec)

mysql>

14.锁定表，目的是不让表继续写了，数据到此暂停，先把这个状态保持在这儿。因为一会儿要做从的机器配置，需要两台机器同步，保证两台机器的数据一致，同步才不会出错

mysql> flush tables with read lock;
Query OK, 0 rows affected (0.10 sec)

mysql>

15.查看一下binlog文件的大小，记住名字和位置

mysql>

16.然后退出数据库，做一个数据同步

17.查看/data/mysql下都有哪些库，主上有哪些库，从上就要同步哪些库，意味着数据都有备份过去

[root@localhost mysql]# ls
aming aminglinux1.index blog ib_logfile0 localhost.localdomain.err mysql performance_schema
aminglinux1.000001 auto.cnf ibdata1 ib_logfile1 localhost.localdomain.pid mysql2 test blog
[root@localhost mysql]#

18.备份数据库，除了mysql库，因为mysql库里面有账号密码，从上的时候不可能把所有权限复制过去，所以mysql不需要备份

[root@localhost mysql]# mysqldump -uroot -paminglinux mysql2 > /tmp/my2.sql
Warning: Using a password on the command line interface can be insecure.
[root@localhost mysql]# mysqldump -uroot -paminglinux zrlog > /tmp/zrlog.sql
Warning: Using a password on the command line interface can be insecure.
[root@localhost mysql]#

19.一会儿把/tmp/下.sql文件都拷贝到从上去

[root@localhost mysql]# ls /tmp/*.sql
/tmp/blog.sql /tmp/my2.sql /tmp/mysql2.sql /tmp/mysql_all.sql /tmp/mysqlbak.sql /tmp/user.sql /tmp/zrlog.sql

20.主上操作完成，接下来从上操作

17.4 配置从

主从配置 - 从上操作

安装mysql
查看my.cnf，配置server-id=132，要求和主不一样
修改完配置文件后，启动或者重启mysqld服务
把主上aming库同步到从上
可以先创建aming库，然后把主上的/tmp/mysql.sql拷贝到从上，然后导入aming库
mysql -uroot
stop slave；
change master to master_host='', master_user='repl', master_password='', master_log_file='', master_log_pos=xx,
start slave;
还要到主上执行 unlock tables

主从配置 - 从上操作

1.首先在从上安装并启动mysql，然后查看my.cnf，配置server-id=130，要求和主不一样，在配置文件的log_bin参数就不需要配置的，因为只有主上才需要二进制日志文件

[root@tianqi-01 ~]# vim /etc/my.cnf

[mysqld]
character_set_server = utf8
datadir=/data/mysql
socket=/tmp/mysql.sock
server-id=130
log_bin=aminglinux1
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
# Settings user and group are ignored when systemd is used.
# If you need to run mysqld under a different user or group,
# customize your systemd unit file for mariadb according to the
# instructions in http://fedoraproject.org/wiki/Systemd

[mysqld_safe]
#log-error=/var/log/mariadb/mariadb.log
#pid-file=/var/run/mariadb/mariadb.pid

#
# include all files from the config directory
#
#!includedir /etc/my.cnf.d

2.重启mysql服务

[root@tianqi-01 ~]# /etc/init.d/mysqld restart
Shutting down MySQL....... [ 确定 ]
Starting MySQL...................... [ 确定 ]
[root@tianqi-01 ~]#

3.增加server-id后，对mysql是没有变化的

[root@tianqi-01 ~]# ls /data/mysql
aming aminglinux1.000007 aminglinux1.000014 aminglinux1.000021 aminglinux1.000028 ib_logfile0 tianqi-01.pid
aminglinux1.000001 aminglinux1.000008 aminglinux1.000015 aminglinux1.000022 aminglinux1.000029 ib_logfile1 zabbix
aminglinux1.000002 aminglinux1.000009 aminglinux1.000016 aminglinux1.000023 aminglinux1.000030 mysql zrlog
aminglinux1.000003 aminglinux1.000010 aminglinux1.000017 aminglinux1.000024 aminglinux1.index mysql2
aminglinux1.000004 aminglinux1.000011 aminglinux1.000018 aminglinux1.000025 auto.cnf performance_schema
aminglinux1.000005 aminglinux1.000012 aminglinux1.000019 aminglinux1.000026 db1 test
aminglinux1.000006 aminglinux1.000013 aminglinux1.000020 aminglinux1.000027 ibdata1 tianqi-01.err
[root@tianqi-01 ~]#

4.把主机器上备份的 .sql 数据，拷贝到从机器上，然后做一个数据恢复

[root@tianqi-01 ~]# scp 192.168.23.136:/tmp/*.sql /tmp/
The authenticity of host '192.168.23.136 (192.168.23.136)' can't be established.
ECDSA key fingerprint is SHA256:A62fDLxjGpEeD/g4UPe/2LtbDTOkiS9zpWjO7w9tZGc.
ECDSA key fingerprint is MD5:04:16:78:f6:50:ad:0a:cf:60:57:b2:b0:cb:2e:f8:4c.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.23.136' (ECDSA) to the list of known hosts.
root@192.168.23.136's password:
blog.sql 100% 1258 1.1MB/s 00:00
my2.sql 100% 638KB 3.7MB/s 00:00
mysql2.sql 100% 30KB 1.8MB/s 00:00
mysql_all.sql 100% 1276KB 2.7MB/s 00:00
mysqlbak.sql 100% 638KB 9.0MB/s 00:00
user.sql 100% 7026 5.8MB/s 00:00
zrlog.sql 100% 1259 950.7KB/s 00:00
[root@tianqi-01 ~]#

5.创建数据库

mysql> create database aming;
Query OK, 1 row affected (0.00 sec)

mysql> create database zrlog;
Query OK, 1 row affected (0.00 sec)

mysql> create database blog;
Query OK, 1 row affected (0.00 sec)

mysql> create database mysql2;
Query OK, 1 row affected (0.00 sec)

mysql>

6.然后将数据做一个恢复

[root@tianqi-01 ~]# mysql -uroot -paminglinux blog < /tmp/blog.sql
Warning: Using a password on the command line interface can be insecure.
[root@tianqi-01 ~]# mysql -uroot -paminglinux zrlog < /tmp/zrlog.sql
Warning: Using a password on the command line interface can be insecure.
[root@tianqi-01 ~]# mysql -uroot -paminglinux mysql2 < /tmp/mysql2.sql
Warning: Using a password on the command line interface can be insecure.
[root@tianqi-01 ~]# mysql -uroot -paminglinux aming < /tmp/blog.sql
Warning: Using a password on the command line interface can be insecure.
[root@tianqi-01 ~]#

7.然后查看/data/mysql/目录下的数据是否和主机器上的/data/mysql/目录是否一致

8.开始实现主从

9.在从机器登录到mysql

[root@tianqi-01 ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 31
Server version: 5.6.35-log MySQL Community Server (GPL)

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql>

10.然后在数据库里面执行命令，停止slave

mysql> stop slave;
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql>

11.进行主机器相关配置

change master to master_host='192.168.23.136', master_user='repl', master_password='aminglinux111', master_log_file='aminglinux1.000001', master_log_pos=428
- master_host='192.168.23.136'，指定主机期host
- master_user='repl'，指定主机器用户
- master_password='aminglinux111'，指定主机器密码
- master_log_file='aminglinux1.000001'，指定binlog文件名
- master_log_pos=428，指定binlog文件大小
也可以指定主机器的port，因为在生产环境中，也会有人更改mysql的默认端口 master_port=3306

mysql> change master to master_host='192.168.23.136', master_user='repl', master_password='aminglinux111', master_log_file='aminglinux1.000001', master_log_pos=428;
Query OK, 0 rows affected, 2 warnings (0.13 sec)

mysql>

12.开始slave

mysql> start slave;
Query OK, 0 rows affected (0.02 sec)

mysql>

13.这时候通过 show slave status\G 判断主从是否配置成功

show slave status\G
- 在G后面不需要加分号，\G本身就是一种结束符
- 看 Slave_IO_Running: Yes 是否为yes
- 看 Slave_SQL_Running: Yes 是否为yes

mysql> show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.23.136
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: aminglinux1.000001
Read_Master_Log_Pos: 428
Relay_Log_File: tianqi-01-relay-bin.000002
Relay_Log_Pos: 285
Relay_Master_Log_File: aminglinux1.000001
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
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: 428
Relay_Log_Space: 462
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:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 136
Master_UUID: 8c4ee77b-6865-11e8-8647-000c2970f861
Master_Info_File: /data/mysql/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set:
Executed_Gtid_Set:
Auto_Position: 0
1 row in set (0.01 sec)

mysql>

注意：这里可能会出现Slave_IO_Running: Connecting错误，主要原因有三个：1、网络不通2、密码不对3、pos不对，仔细检查发现这3项没有错误之后，检查一下主的防火墙是或关闭

14.解锁主上的表

mysql> unlock tables;
Query OK, 0 rows affected (0.09 sec)

15.到这里主从搭建就算完成了

查看主从同步是否正常

从上执行mysql -uroot
show slave stauts\G
看是否有
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
还需关注
Seconds_Behind_Master: 0 //为主从延迟的时间
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:

17.5 测试主从同步

1.主进入MySQL，使用aming数据库

[root@localhost ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 5.6.35-log MySQL Community Server (GPL)

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> use aming;
Database changed

2.创建数据表t1

mysql> create table t1(`id` int(4),`name` char(20));
Query OK, 0 rows affected (0.66 sec)

3.查看数据表t1

mysql> show tables;
+-----------------+
| Tables_in_aming |
+-----------------+
| t1 |
+-----------------+
1 row in set (0.00 sec)

mysql> show create table t1\G
*************************** 1. row ***************************
Table: t1
Create Table: CREATE TABLE `t1` (
`id` int(4) DEFAULT NULL,
`name` char(20) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1
1 row in set (0.10 sec)

mysql>

4.从上进入MySQL，使用aming数据库

[root@tianqi-01 ~]# mysql -uroot -p
Enter password:
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)
[root@tianqi-01 ~]# mysql -uroot -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2092
Server version: 5.6.35-log MySQL Community Server (GPL)

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> use aming;
Database changed
5.查看所有数据表

mysql> show tables;
+-----------------+
| Tables_in_aming |
+-----------------+
| t1 |
+-----------------+
1 row in set (0.00 sec)

6.查看数据表t1的建表语句，结果与主的一致，说明主从一直

mysql> show create table t1;
+-------+---------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+---------------------------------------------------------------------------------------------------------------------+
| t1 | CREATE TABLE `t1` (
`id` int(4) DEFAULT NULL,
`name` char(20) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8 |
+-------+---------------------------------------------------------------------------------------------------------------------+
1 row in set (0.20 sec)

mysql> show create table t1\G;
*************************** 1. row ***************************
Table: t1
Create Table: CREATE TABLE `t1` (
`id` int(4) DEFAULT NULL,
`name` char(20) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

ERROR:
No query specified

mysql>

来源：oschina

链接：https://my.oschina.net/u/3744518/blog/1831590

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