MySQL
manager or server PID file could not be found!       [FAILED]

解决办法：

首先查看一下进程

[root@irxpert-test /]# ps aux |grep mysq*

root    10274 0.0 0.0 68160 1336
?       S   13:43  0:00 /bin/sh
/usr/bin/mysqld_safe –datadir=/var/lib/mysql
–pid-file=/var/lib/mysql/irxpert-test.pid
mysql   10353 0.0 1.0 344360 39464
?       Sl  13:43  0:00 /usr/sbin/mysqld
–basedir=/usr –datadir=/var/lib/mysql
–plugin-dir=/usr/lib64/mysql/plugin –user=mysql
–log-error=/var/lib/mysql/irxpert-test.err
–pid-file=/var/lib/mysql/irxpert-test.pid
root    11884 0.0 0.0 63384  760
pts/1   S+  15:44  0:00 grep mysq*

如果看到上面的内容，那说明，Mysql的进程卡死了，这时用就要把这些卡死的进程都关闭

[root@centos mysql]# kill 10274

[root@centos mysql]# kill 10353

启动Mysql就ok了

[root@centos mysql]# service mysql start

Starting MySQL.                                            [  OK  ]