故障集，更新中……

一、nginx无法重启，显示端口已被占用

 nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)

[root@cm local]# netstat -natp | grep :80
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      8858/nginx: master  
[root@cm local]# lsof -i:80
COMMAND  PID  USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
nginx   8858  root    6u  IPv4  33972      0t0  TCP *:http (LISTEN)
nginx   8859 nginx    6u  IPv4  33972      0t0  TCP *:http (LISTEN)
[root@cm local]# kill -9 8858
[root@cm local]# lsof -i:80
COMMAND  PID  USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
nginx   8859 nginx    6u  IPv4  33972      0t0  TCP *:http (LISTEN)
[root@cm local]# systemctl restart nginx.service 
Job for nginx.service failed because the control process exited with error code. See "systemctl status nginx.service" and "journalctl -xe" for details.
[root@cm local]# systemctl status nginx.service 
● nginx.service - nginx
   Loaded: loaded (/usr/lib/systemd/system/nginx.service; enabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since 三 2021-08-18 12:15:23 CST; 12s ago
  Process: 13254 ExecStart=/usr/local/nginx/sbin/nginx (code=exited, status=1/FAILURE)
 Main PID: 874 (code=exited, status=0/SUCCESS)

8月 18 12:15:20 cm nginx[13254]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
8月 18 12:15:21 cm nginx[13254]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
8月 18 12:15:21 cm nginx[13254]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
8月 18 12:15:22 cm nginx[13254]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
8月 18 12:15:22 cm nginx[13254]: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
8月 18 12:15:23 cm systemd[1]: nginx.service: control process exited, code=exited status=1
8月 18 12:15:23 cm nginx[13254]: nginx: [emerg] still could not bind()
8月 18 12:15:23 cm systemd[1]: Failed to start nginx.
8月 18 12:15:23 cm systemd[1]: Unit nginx.service entered failed state.
8月 18 12:15:23 cm systemd[1]: nginx.service failed.
Use the ``-h'' option to get more help information.
[root@cm local]# lsof -i:80
COMMAND  PID  USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
nginx   8859 nginx    6u  IPv4  33972      0t0  TCP *:http (LISTEN)
[root@cm local]# kill -9 8859
[root@cm local]# lsof -i:80
[root@cm local]# netstat -natp | grep :80
[root@cm local]# systemctl restart nginx.service 

　　

二、"Can't locate CPAN.pm in @INC " 解决方案

[root@mysql1 mha4mysql-node-0.57]# ls
AUTHORS  bin  COPYING  debian  inc  lib  Makefile.PL  MANIFEST  META.yml  README  rpm  t
[root@mysql1 mha4mysql-node-0.57]# perl Makefile.PL 
*** Module::AutoInstall version 1.06
*** Checking for Perl dependencies...
Can't locate CPAN.pm in @INC (@INC contains: inc /usr/local/lib64/perl5 /usr/local/share/perl5 /usr/lib64/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib64/perl5 /usr/share/perl5 .) at inc/Module/AutoInstall.pm line 304.

【解决方案】

这个问题就是说，没有安装perl-CPAN,解决就很简单了，安装个perl-CPAN：

#yum install perl-CPAN 

[root@mysql1 mha4mysql-node-0.57]# yum install perl-CPAN
已安装:
  perl-CPAN.noarch 0:1.9800-299.el7_9                                                                                                      

作为依赖被安装:
  perl-Digest.noarch 0:1.17-245.el7          perl-Digest-SHA.x86_64 1:5.85-4.el7          perl-local-lib.noarch 0:1.008010-4.el7         

完毕！
[root@mysql1 mha4mysql-node-0.57]# perl Makefile.PL 
*** Module::AutoInstall version 1.06
*** Checking for Perl dependencies...
[Core Features]
- DBI        ...loaded. (1.627)
- DBD::mysql ...loaded. (4.023)
*** Module::AutoInstall configuration finished.
Checking if your kit is complete...
Looks good
Writing Makefile for mha4mysql::node

　　

三、[ERROR] unknown variable 'default-character-set=utf8'

masterha_check_repl -conf=/etc/masterha/app1.cnf  健康检查时报错

查看日志：发现其中提示：

Tue Sep 7 13:18:55 2021 - [info] Connecting to root@192.168.229.80(192.168.229.80:22)..
mysqlbinlog: [ERROR] unknown variable 'default-character-set=utf8'

default-character-set=utf8这个设置有问题，系统无法识别，将非必要项删除或者注释掉即可

修改192.168.229.80主机的配置文件/etc/my.cnf

重启mysql服务，再次检查，OK

四、MySQL主从复制，启动slave时报错Slave failed to initialize relay log info structure from the repository

症状：

MySQL主从复制，启动slave时，出现下面报错：

mysql> start slave;
ERROR 1872 (HY000): Slave failed to initialize relay log info structure from the repository

解决方法：

在网上搜索

原来是找不到./server246-relay-bin.index文件，找到原因所在了，由于我使用的是冷备份文件恢复的实例，在mysql库中的slave_relay_log_info表中依然保留之前relay_log的信息，所以导致启动slave报错。
mysql提供了工具用来删除记录：reset slave；
slave reset执行候做了这样几件事：
1、删除slave_master_info ，slave_relay_log_info两个表中数据；
2、删除所有relay log文件，并重新创建新的relay log文件；
3、不会改变gtid_executed 或者 gtid_purged的值

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

mysql> change master to master_host='192.168.229.90',master_user='replication',master_password='12345',master_log_file='mysql_bin.000002',maaster_log_pos=1386;
Query OK, 0 rows affected, 2 warnings (0.04 sec)

mysql> start slave;
Query OK, 0 rows affected (0.01 sec)

mysql> show slave status\G;
*************************** 1. row ***************************
               Slave_IO_State: Waiting for master to send event
                  Master_Host: 192.168.229.90
                  Master_User: replication
                  Master_Port: 3306
                Connect_Retry: 60
              Master_Log_File: mysql_bin.000002
          Read_Master_Log_Pos: 1386
               Relay_Log_File: 192-relay-bin.000002
                Relay_Log_Pos: 320
        Relay_Master_Log_File: mysql_bin.000002
             Slave_IO_Running: Yes
            Slave_SQL_Running: Yes