MySQL MHA配置的常见问题及解决方法

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问题一：

Thu Aug 23 04:39:01 2018 - [warning]  log-bin is not set on slave 192.168.0.189(192.168.0.189:3306). This host cannot be a master.

Thu Aug 23 04:39:01 2018 - [warning]  log-bin is not set on slave 192.168.0.190(192.168.0.190:3306). This host cannot be a master.

解决办法：

从库的各客户端应开启binlog，即log_bin=on，两个从上都开启

[root@centos7-02 ~]# vi /etc/my.cnf

 basedir = /usr/local/mysql

 datadir = /data/mysql

 socket = /tmp/mysql.sock

 server-id=189

 log_bin=on

问题二：

Can't exec "mysqlbinlog": 没有那个文件或目录 at /usr/local/share/perl5/MHA/BinlogManager.pm line 106.

mysqlbinlog version command failed with rc 1:0, please verify PATH, LD_LIBRARY_PATH, and client options

 at /usr/local/bin/apply_diff_relay_logs line 493.

解决办法：

在所有节点上执行如下命令

[root@centos7-01 ~]# ln -s /usr/local/mysql/bin/mysqlbinlog /usr/local/bin/mysqlbinlog

[root@centos7-01 ~]# ln -s /usr/local/mysql/bin/mysql /usr/local/bin/mysql

[root@centos7-02 ~]# ln -s /usr/local/mysql/bin/mysqlbinlog /usr/local/bin/mysqlbinlog

[root@centos7-02 ~]# ln -s /usr/local/mysql/bin/mysql /usr/local/bin/mysql

[root@centos7-03 ~]# ln -s /usr/local/mysql/bin/mysqlbinlog /usr/local/bin/mysqlbinlog

[root@centos7-03 ~]# ln -s /usr/local/mysql/bin/mysql /usr/local/bin/mysql

问题三：

Thu Aug 23 05:41:59 2018 - [error][/usr/local/share/perl5/MHA/MasterMonitor.pm, ln226]  Failed to get master_ip_failover_script status with return code 1:0.

Thu Aug 23 05:41:59 2018 - [error][/usr/local/share/perl5/MHA/MasterMonitor.pm, ln424] Error happened on checking configurations.  at /usr/local/bin/masterha_check_repl line 48

Thu Aug 23 05:41:59 2018 - [error][/usr/local/share/perl5/MHA/MasterMonitor.pm, ln523] Error happened on monitoring servers.

解决办法：

[root@centos7-04 ~]# vi /etc/masterha/app1.cnf

#master_ip_failover_script= /usr/local/bin/master_ip_failover            //先暂时注释这条选项，后面引入keepalived后和修改该脚本以后再开启该选项

注释：Failover有两种方式：一种是虚拟IP地址，一种是全局配置文件。MHA并没有限定使用哪一种方式，而是让用户自己选择，虚拟IP地址的方式会牵扯到其它的软件,比如keepalive软件，而且还要修改脚本master_ip_failover。

问题四：

Thu Aug 23 18:17:14 2018 - [error][/usr/local/share/perl5/MHA/MasterMonitor.pm, ln424] Error happened on checking configurations. Can't exec "/usr/local/bin/master_ip_failover": 权限不够 at /usr/local/share/perl5/MHA/ManagerUtil.pm line 68.

Thu Aug 23 18:17:14 2018 - [error][/usr/local/share/perl5/MHA/MasterMonitor.pm, ln523] Error happened on monitoring servers.

解决办法:

chmod +x /usr/local/bin/master_ip_failover

问题五：

[error][/usr/local/share/perl5/MHA/ServerManager.pm, ln492]  Server 192.168.0.190(192.168.0.190:3306) is dead, but must be alive! Check server settings.

解决办法：

[root@centos7-04 ~]# rm -rf /var/log/masterha/app1.log/app1.failover.complete        #删除MHA管理机上的这个文件

问题六：

[error][/usr/local/share/perl5/MHA/ServerManager.pm, ln492]  Server 192.168.0.190(192.168.0.190:3306) is dead, but must be alive! Check server settings.

解决办法：

清除防火墙规则

问题七：

[error][/usr/local/share/perl5/MHA/ServerManager.pm, ln492]  Server 192.168.0.188(192.168.0.188:3306) is dead, but must be alive! Check server settings.

Fri Aug 24 23:50:37 2018 - [error][/usr/local/share/perl5/MHA/MasterMonitor.pm, ln424] Error happened on checking configurations.  at /usr/local/share/perl5/MHA/MasterMonitor.pm line 399

解决办法：

重启主库的mysql服务

问题八：

[error][/usr/local/share/perl5/MHA/MasterMonitor.pm, ln205] Slaves settings check failed!

解决办法：

登陆从数据库，查看主数据库是不是自己设定的

mysql> show slave status\G

Master_Server_Id: 189

问题九：

[error][/usr/local/share/perl5/MHA/ServerManager.pm, ln781] Multi-master configuration is detected, but two or more masters are either writable (read-only is not set) or dead! Check configurations for details. Master configurations are as below: 

Master 192.168.0.189(192.168.0.189:3306), dead

Master 192.168.0.188(192.168.0.188:3306), replicating from 192.168.0.189(192.168.0.189:3306)

解决办法：

所有从上执行

mysql -uroot -p -e "set global read_only=1"

问题十：

mysqlbinlog: unknown variable 'default-character-set=utf8'

mysqlbinlog version command failed with rc 7:0, please verify PATH, LD_LIBRARY_PATH, and client options

解决办法：

在所有从上注释掉clinet段default-character-set=utf8mb4

更改默认字符集UTF8到utf8mb4

[client]

#default-character-set = utf8mb4 

[mysql]

default-character-set = utf8mb4

[mysqld]

character-set-client-handshake = FALSE

character-set-server = utf8mb4

collation-server = utf8mb4_unicode_ci

init_connect='SET NAMES utf8mb4'