1,背景需求

由于现网的环境，经过近期监控，发现MYSQL主库的IO读写压力比较大，需要部署新的MYSQL从库，进一步分摊MYSQL主库的压力，以及现存MYSQL从库的读负载。为了减少对于MYSQL主库的IO读取性能冲击，采用基于MYSQL现存从库构建新的MYSQL从库。

2，现存的数据库架构

编号IP地址数据库角色

1 10.0.0.12数据库主库

2 10.0.0.16数据库从库1

3，准备好一个新的数据库从库2

编号IP地址数据库角色

3 10.0.0.14 数据库从库2

4，在新的数据库从库2，配置server_id=3,区别于上述2个节点

5，在数据库从库1，关闭sql thread,为了实现MYSQLDUMP备份的数据一致性；

mysql> system hostname

standby3

mysql> stop slave;

Query OK, 0 rows affected (0.01 sec)

6，在数据库从库1，获取show slave status之如下标注的2个列

（注：用于基于这个列的值，用于后续构建新的MYSQL从库）

mysql> show slave status\G;

*************************** 1. row ***************************

Slave_IO_State:

Master_Host: 10.0.0.12

Master_User: repl

Master_Port: 3306

Connect_Retry: 60

Master_Log_File: binlog.000002

Read_Master_Log_Pos: 120

Relay_Log_File: standby3-relay-bin.000004

Relay_Log_Pos: 280

Relay_Master_Log_File: binlog.000002---应用主库二进制日志

Slave_IO_Running: No

Slave_SQL_Running: No

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: 120---应用主库二进制日志的位置

Relay_Log_Space: 500

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: 0

Last_IO_Error:

Last_SQL_Errno: 0

Last_SQL_Error:

Replicate_Ignore_Server_Ids:

Master_Server_Id: 1

Master_UUID: 65fddb9f-fd33-11e9-95f0-080027d1f3fc

Master_Info_File: /var/lib/mysql/master.info

SQL_Delay: 0

SQL_Remaining_Delay: NULL

Slave_SQL_Running_State:

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 (0.00 sec)

ERROR:

No query specified

mysql>

7，在MYSQL从库1导出数据库备份

[root@standby3 mysql]# mysqldump -uroot -psystem --databases zxydb >/dump_dir/for_create_2_slave.dump

Warning: Using a password on the command line interface can be insecure.

[root@standby3 mysql]#

8，重启MYSQL从库1的SQL THREAD

mysql> start slave sql_thread;

Query OK, 0 rows affected (0.01 sec)

9，把MYSQL从库1 复制数据库份到 MYSQL从库2

[root@standby2mysql mysql]# mkdir -p /dump_dir

[root@standby2mysql mysql]#

[root@standby3 mysql]# scp /dump_dir/for_create_2_slave.dump root@10.0.0.14:/dump_dir/

root@10.0.0.14's password:

for_create_2_slave.dump100% 2530 2.5KB/s00:00

[root@standby3 mysql]#

10，在MYSQL从库2导入DUMP文件

[root@standby2mysql mysql]# mysql -uroot -psystem </dump_dir/for_create_2_slave.dump

Warning: Using a password on the command line interface can be insecure.

[root@standby2mysql mysql]#

[root@standby2mysql mysql]# mysql -uroot -psystem

Warning: Using a password on the command line interface can be insecure.

Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection id is 3

Server version: 5.6.25-enterprise-commercial-advanced-log MySQL Enterprise Server - Advanced Edition (Commercial)

Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.

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> show databases;

+--------------------+

| Database|

+--------------------+

| information_schema |

| mysql |

| performance_schema |

| test|

| zxydb |

+--------------------+

5 rows in set (0.00 sec)

11，在MYSQL主库创建用于构建MYSQL从库2连接MYSQL主库的复制数据库用户

mysql> create user 'repl'@'10.0.0.14' identified by 'system';

Query OK, 0 rows affected (0.00 sec)

mysql> grant replication slave on *.* to 'repl'@'10.0.0.14';

Query OK, 0 rows affected (0.00 sec)

12，在MYSQL从库2构建至MYSQL主库的主从复制关系

mysql> change master to master_host='10.0.0.12',master_user='repl',master_password='system',master_log_file='binlog.000002',master_log_pos=120;

Query OK, 0 rows affected, 2 warnings (0.03 sec)

13，在MYSQL从库2 启动主从复制服务

mysql> start slave;

Query OK, 0 rows affected (0.01 sec)

14，在MYSQL从库2查看主从复制运行

mysql> show slave status\G;

*************************** 1. row ***************************

Slave_IO_State: Waiting for master to send event

Master_Host: 10.0.0.12

Master_User: repl

Master_Port: 3306

Connect_Retry: 60

Master_Log_File: binlog.000002

Read_Master_Log_Pos: 437

Relay_Log_File: standby2mysql-relay-bin.000003

Relay_Log_Pos: 280

Relay_Master_Log_File: binlog.000002

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: 437

Relay_Log_Space: 938

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: 1

Master_UUID: 65fddb9f-fd33-11e9-95f0-080027d1f3fc

Master_Info_File: /var/lib/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 (0.00 sec)

ERROR:

No query specified

15，验证MYSQL主库与新部署的MYSQL从库2 数据同步正常

--MYSQL主库

mysql> use zxydb;

Database changed

mysql> insert into t_go select 5,5;

Query OK, 1 row affected (0.01 sec)

Records: 1 Duplicates: 0 Warnings: 0

mysql> commit;

Query OK, 0 rows affected (0.00 sec)

mysql> select * from t_go;

+---+------+

| a | b|

+---+------+

| 1 |1 |

| 2 |2 |

| 3 |3 |

| 5 |5 |

+---+------+

4 rows in set (0.00 sec)

---MYSQL从库2

mysql> select * from zxydb.t_go;

+---+------+

| a | b|

+---+------+

| 1 |1 |

| 2 |2 |

| 3 |3 |

| 5 |5 |

+---+------+

4 rows in set (0.00 sec)

16，在MYSQL主库执行，可见现配置2个MYSQL从库

mysql> show slave hosts;

+-----------+------+------+-----------+--------------------------------------+

| Server_id | Host | Port | Master_id | Slave_UUID|

+-----------+------+------+-----------+--------------------------------------+

| 3 | | 3306 | 1 | 699a379f-e36d-11e9-a4e2-0800274dcc79 |

| 2 | | 3306 | 1 | 891bc123-fd72-11e9-8cf5-080027dddbcd |

+-----------+------+------+-----------+--------------------------------------+

2 rows in set (0.00 sec)

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