MySQL MHA配置常见问题
# masterha_check_repl --conf=/etc/masterha/app1.cnf问题一：
Thu Aug 23 04:39:01 2018 - 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 - 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
# 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
# ln -s /usr/local/mysql/bin/mysqlbinlog /usr/local/bin/mysqlbinlog
# ln -s /usr/local/mysql/bin/mysql /usr/local/bin/mysql
# ln -s /usr/local/mysql/bin/mysqlbinlog /usr/local/bin/mysqlbinlog
# ln -s /usr/local/mysql/bin/mysql /usr/local/bin/mysql
# ln -s /usr/local/mysql/bin/mysqlbinlog /usr/local/bin/mysqlbinlog
# ln -s /usr/local/mysql/bin/mysql /usr/local/bin/mysql
问题三：
Thu Aug 23 05:41:59 2018 - Failed to get master_ip_failover_script status with return code 1:0.
Thu Aug 23 05:41:59 2018 - Error happened on checking configurations.at /usr/local/bin/masterha_check_repl line 48
Thu Aug 23 05:41:59 2018 - Error happened on monitoring servers.
解决办法：
# 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 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 happened on monitoring servers.
解决办法:
chmod +x /usr/local/bin/master_ip_failover
问题五：
Server 192.168.0.190(192.168.0.190:3306) is dead, but must be alive! Check server settings.
解决办法：
# 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：
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：
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 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：
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：
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：
在所有从服务器上注释掉clinet段default-character-set=utf8mb4
更改默认字符集UTF8到utf8mb4
#default-character-set = utf8mb4
default-character-set = utf8mb4
character-set-client-handshake = FALSE
character-set-server = utf8mb4
collation-server = utf8mb4_unicode_ci
init_connect='SET NAMES utf8mb4'
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