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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.dump 100% 2530 2.5KB/s 00:00
[root@standby3 mysql]#
10，在MYSQL从库2导入DUMP文件
[root@standby2mysql mysql]# mysql -uroot -psystem
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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