MySQL主从复制
实验准备：
2台MySQL服务器：
master ：192.168.78.132
slave：192.168.78.148
主从复制原理
- 在master上开启二进制日志
- master上数据发生变化时，会产生二进制日志
- master上的dump线程会通知slave上的io线程来拿二进制日志，后写入slave的中继日志，然后SQL线程会读取新产生的中继日志，重演二进制日志里的操作，从而达到slave和master上的数据一模一样，保持一致性。
一、开启二进制日志
在主服务器上开启二进制日志，server_id=1
[root@mysql-master ~]# vim /etc/my.cnf
[mysqld]
...
#log bin
log_bin
server_id = 1
在从服务器上也可以开启二进制日志，server_id=2
[root@mysql-slave ~]# vim /etc/my.cnf
[mysqld]
...
#log bin
log_bin
server_id = 2
二、同步数据库数据
导出主服务器数据库里的内容，然后导入到从服务器里
1.Master上导出数据
[root@mysql-master ~]# mysqldump -uroot -p"Sanchuang123#" --all-databases >/backup/all_db.sql
mysqldump: [Warning] Using a password on the command line interface can be insecure.
2.导入数据到slave
将数据文件上传到从服务器上，导入数据，从而实现主从上的初始数据一致：
master服务器上操作：
#需要先建立免密通道
[root@mysql-master ~]# scp /backup/all_db.sql 192.168.78.148:/root
all_db.sql 100% 885KB 79.4MB/s 00:00
slave服务器上操作：
[root@mysql-slave ~]# mysql -uroot -p'Sanchuang123#' <all_db.sql
mysql: [Warning] Using a password on the command line interface can be insecure.
三.新建授权用户
在master服务器上的MySQL中刷新一下，产生一个新的日志，方便后面的操作：
root@(none) 19:33 mysql>flush logs;
Query OK, 0 rows affected (0.01 sec)
root@(none) 19:36 mysql>show master status; #查看当前正在使用的二进制日志文件
+-------------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+-------------------------+----------+--------------+------------------+-------------------+
| mysql-master-bin.000003 | 154 | | | |
+-------------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
在master服务器的MySQL中新建用户：
root@(none) 19:36 mysql>grant replication slave on *.* to 'sc'@'192.168.78.%' identified by 'Sanchuang123#';
Query OK, 0 rows affected, 1 warning (0.00 sec)
root@(none) 19:41 mysql>flush privileges; #刷新 MySQL 权限
Query OK, 0 rows affected (0.00 sec)
root@(none) 19:42 mysql>show show grants for 'sc'@'192.168.78.%'; #用于显示指定用户在 MySQL 中的授权信息
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'show grants for 'sc'@'192.168.78.%'' at line 1
root@(none) 19:42 mysql>show grants for 'sc'@'192.168.78.%';
+-------------------------------------------------------+
| Grants for sc@192.168.78.% |
+-------------------------------------------------------+
| GRANT REPLICATION SLAVE ON *.* TO 'sc'@'192.168.78.%' |
+-------------------------------------------------------+
1 row in set (0.01 sec)
四、在slave从服务器上配置
root@(none) 19:58 mysql>CHANGE MASTER TO MASTER_HOST='192.168.78.132' ,
-> MASTER_USER='sc', #创建的授权用户
-> MASTER_PASSWORD='Sanchuang123#', #密码
-> MASTER_PORT=3306, #master的MySQL端口号
-> MASTER_LOG_FILE='mysql-master-bin.000003', #master正在使用的二进制文件
-> MASTER_LOG_POS=154; #二进制文件现在的pos
Query OK, 0 rows affected, 2 warnings (0.00 sec)
查看从服务器的状态：
root@(none) 19:58 mysql>show slave status\G;
*************************** 1. row ***************************
Slave_IO_State:
Master_Host: 192.168.78.132
Master_User: sc
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-master-bin.000003
Read_Master_Log_Pos: 154
Relay_Log_File: mysql-slave-relay-bin.000001
Relay_Log_Pos: 4
Relay_Master_Log_File: mysql-master-bin.000003
Slave_IO_Running: No #从服务器的IO线程没有起来
Slave_SQL_Running: No #从服务器的SQL线程没有起来
开启SQL线程：
root@(none) 20:01 mysql>stop slave; #停止从服务器上的主从复制
Query OK, 0 rows affected (0.00 sec)
root@(none) 20:03 mysql>start slave; #开启从服务器上的主从复制
Query OK, 0 rows affected (0.00 sec)
root@(none) 20:03 mysql>show slave status\G;
*************************** 1. row ***************************
Slave_IO_State:
Master_Host: 192.168.78.132
Master_User: sc
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-master-bin.000003
Read_Master_Log_Pos: 154
Relay_Log_File: mysql-slave-relay-bin.000001
Relay_Log_Pos: 4
Relay_Master_Log_File: mysql-master-bin.000003
Slave_IO_Running: No
Slave_SQL_Running: Yes #发现sql线程开启成功，io没有成功
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: 154
Relay_Log_Space: 154
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: NULL
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 1593
Last_IO_Error: Fatal error: The slave I/O thread stops because master and slave have equal MySQL server UUIDs; these UUIDs must be different for replication to work. #发现io不成功是uuid问题
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 1
Master_UUID:
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 more updates
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp: 230717 20:03:35
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set:
Executed_Gtid_Set:
Auto_Position: 0
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
1 row in set (0.00 sec)
ERROR:
No query specified
解决UUID一样的问题：
root@(none) 20:07 mysql> show variables like "%uuid%";
+---------------+--------------------------------------+
| Variable_name | Value |
+---------------+--------------------------------------+
| server_uuid | 8cccc5f7-be7a-11ed-8855-000c29398d80 |
+---------------+--------------------------------------+
1 row in set (0.00 sec)
修改几个字符就可以，和主服务器里的不一样就可以：
[root@mysql-slave ~]# cd /data/mysql #MySQL数据目录
[root@mysql-slave mysql]# vim auto.cnf
[auto]
server-uuid=8cccc5f7-be7a-11ed-8855-000c29398d81
[root@mysql-slave mysql]# service mysqld restart
Shutting down MySQL.... SUCCESS!
Starting MySQL. SUCCESS!
问题成功解决：
root@(none) 20:09 mysql>show slave status\G;
ERROR 2006 (HY000): MySQL server has gone away
No connection. Trying to reconnect...
Connection id: 4
Current database: *** NONE ***
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.78.132
Master_User: sc
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-master-bin.000003
Read_Master_Log_Pos: 598
Relay_Log_File: mysql-slave-relay-bin.000003
Relay_Log_Pos: 771
Relay_Master_Log_File: mysql-master-bin.000003
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
成功后，查看文件：
[root@mysql-slave mysql]# cat master.info
25
mysql-master-bin.000003
598
192.168.78.132
sc
Sanchuang123#
3306
60
0
0
30.000
0
8cccc5f7-be7a-11ed-8855-000c29398d80
86400
0
[root@mysql-slave mysql]# cat relay-log.info
7
./mysql-slave-relay-bin.000003
771
mysql-master-bin.000003
598
0
0
1
Master上如何知道有哪些从服务器？
root@(none) 19:51 mysql>SHOW SLAVE HOSTS;
+-----------+------+------+-----------+--------------------------------------+
| Server_id | Host | Port | Master_id | Slave_UUID |
+-----------+------+------+-----------+--------------------------------------+
| 2 | | 3306 | 1 | 8cccc5f7-be7a-11ed-8855-000c29398d81 |
+-----------+------+------+-----------+--------------------------------------+
1 row in set (0.00 sec)
五、验证主从复制是否成功
在master服务器是建库建表：
root@(none) 20:16 mysql>create database db1;
Query OK, 1 row affected (0.00 sec)
root@(none) 20:19 mysql>use db1
Database changed
root@db1 20:19 mysql>create table t1(id int ,name varchar(20));
Query OK, 0 rows affected (0.01 sec)
root@db1 20:20 mysql> insert into t1 values(1,'lisi');
Query OK, 1 row affected (0.00 sec)
root@db1 20:20 mysql>select * from t1;
+------+------+
| id | name |
+------+------+
| 1 | lisi |
+------+------+
1 row in set (0.00 sec)
slave服务器上查看是否存在：
root@(none) 20:16 mysql>use db1
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
root@db1 20:22 mysql>select * from t1;
+------+------+
| id | name |
+------+------+
| 1 | lisi |
+------+------+
1 row in set (0.00 sec)