MySQL之-主从server-id不生效的示例代码（图）

数据库已搭建完成，各种配置均已完成，但是在start slave ;的时候，报错：

ERROR 1200 (HY000): The server is not configured as slave; fix in config file or with CHANGE MASTER TO

这里说，我没有配置为从机，但我明明配置过的啊。

MySQL版本：5.6.19

主：master IP  :  172.17.210.199
从：slave    IP ：172.17.206.138
先看看从机172.17.206.138的my.cnf

[root@liuyazhuang ~]# vi /etc/my.cnf
[mysqld]
datadir=/usr/local/mysql/data
socket=/tmp/mysql.sock
skip-grant-tables
user=mysql
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
tmpdir=/tmp
[mysqld_safe]
log-error=/usr/local/data/mysqld.log
pid-file=/usr/local/mysql/data/mysqld.pid
###############以下是添加主从的配置
server_id = 2
log-bin = /usr/local/mysql/log/solve-bin.log
master-host = 172.17.210.199
master-user = test
master-pass = 123456
master-port = 3306
master-connect-retry = 60

这是MySQL主机172.17.210.199的my.cnf

[root@liuyazhuang ~]$ cat /etc/my.cnf
[mysqld]
log-bin = /u01/mysql/log/masters-bin.log
read-only = 0
basedir = /u01/mysql
datadir = /u01/mysql/data
port = 3306
server_id = 1
socket = /tmp/mysql.sock
join_buffer_size = 128M
sort_buffer_size = 2M
read_rnd_buffer_size = 2M

sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES

尝试过多次 重启主从还是报错;
接着手动chang to 后还是一样报错

mysql> CHANGE MASTER TO
MASTER_HOST='172.17.210.199',
MASTER_USER='test',
MASTER_PASSWORD='123456',
MASTER_LOG_FILE='masters-bin.000003',
MASTER_LOG_POS=120;
Query OK, 0 rows affected, 2 warnings (0.04 sec)

在从库服务器执行START slave;命令启动slave

mysql> START slave;

报错:
ERROR 1200 (HY000): The server is not configured as slave; fix in config file or with CHANGE MASTER TO

于是查看日志
1.查看SLAVE172.17.206.138上的Mysql报错日志，有这么一句：
141009  6:06:29 [ERROR] Server id not set, will not start slave

意思是，slave的server-id没有设置。
那就奇怪了，我明明在配置文件里面指定了server-id的了，并且有重启mysql服务，难道不起效？
分别在主从上执行命令“show variables like 'server_id';”。

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-------从机上面查看端口

mysql> mysql> SHOW VARIABLES LIKE 'server_id';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| server_id     | 0     |
+---------------+-------+
1 row in set (0.00 sec)

命名设置的是2，怎么会变成0

-------主机上面查看

mysql> SHOW VARIABLES LIKE 'server_id';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| server_id     | 1     |
+---------------+-------+
1 row in set (0.00 sec)

跟设置的一样。
既然参数文件不生效，就试试在数据库命令里面设置：在从机 172.17.206.138上执行命令

mysql > SET GLOBAL server_id=2;

再次在从机 172.17.206.138上执行slave start和show slave status，成功了。
         注意！！！由于“SET GLOBAL server_id=;”命令会在mysql服务重启后丢失，所以一定要写到配置文件里面。
但为什么我之前修改了my.cnf文件不起效？
仔细排查，发现配置里面有[mysqld]和[mysqld_safe]，之前将修改的配置内容基本都放在了[mysqld_safe]下面，新增的配置文件放的位置不一样也有关系？于是我尝试把配置文件里修改的部分放在[mysqld]下面，于是改成这样：

[root@liuyazhuang]# cat  /etc/my.cnf
[mysqld]
datadir=/usr/local/mysql/data
socket=/tmp/mysql.sock
skip-grant-tables
user=mysql
symbolic-links=0
tmpdir=/tmp
server_id = 2
log-bin = /usr/local/mysql/log/solve-bin.log
master-host = 172.17.210.199
master-user = test
master-pass = 123456
master-port = 3306
master-connect-retry = 60

[mysqld_safe]
log-error=/usr/local/data/mysqld.log
pid-file=/usr/local/mysql/data/mysqld.pid

如图，就是将图中标注的内容从[mysqld_safe]下修改到[mysqld]下

修改之后，再次同步，成功了！

mysql>
mysql> STOP slave;
Query OK, 0 rows affected (0.05 sec)

mysql> START slave;
Query OK, 0 rows affected (0.00 sec)