mysql启动时报如下错误：ERROR! The server quit without updating PID file (/data/mysql/localhost_002.pid).

[root@localhost_002 mysql]# /etc/init.d/mysqld startStarting MySQL. ERROR! The server quit without updating PID file (/data/mysql/localhost_002.pid).

查看错误日记时发现好多IonoDB的错误：

在百度上搜索到的结果及排查步骤如下：

1、可能是进程已经存在了mysql的进程：发现没有这个进程：

解决方法：用ps aux |grep msyql 查看,并且用kill -9 杀死，然后重启mysql；

[root@localhost_002 ~]# ps aux |grep mysqldroot 1176 0.0 0.0 112720 972 pts/0 S+ 22:07 0:00 grep --color=auto mysqld

2、可能是mysql的数据库目录所属主和组不是mysql,或者是没有执行权限；修改后还是不行；

[root@localhost_002 mysql]# chown -R mysql:mysql /data/mysql/[root@localhost_002 mysql]# chmod -R 755 /data/mysql/[root@localhost_002 mysql]# /etc/init.d/mysqld startStarting MySQL. ERROR! The server quit without updating PID file (/data/mysql/localhost_002.pid).

3、可能是第二次在机器上安装mysql，有残余数据影响了服务的启动；本机不存在这种类型的文件；

解决方法：去mysql的数据目录/data/mysql/看看，如果存在mysql-bin.index，就赶快把它删除掉；

4、mysql在启动时没有指定datadir：配置文件：/etc/my.cnf

[root@localhost_002 mysql]# vim /etc/my.cnfdatadir=/data/mysqlsocket=/tmp/mysql.sock[root@localhost_002 mysql]# service mysqld startStarting MySQL. ERROR! The server quit without updating PID file (/data/mysql/localhost_002.pid).

5、skip-federated字段问题；还是不行：

解决方法：检查一下/etc/my.cnf文件中有没有没被注释掉的skip-federated字段，如果有就立即注释掉；

6、selinux的问题：关闭它；

[root@localhost_002 mysql]# getenforceDisabled[root@localhost_002 ~]# service mysqld startStarting MySQL. ERROR! The server quit without updating PID file (/data/mysql/localhost_002.pid).

无果,再次查看日记如下：

2018-10-04 22:19:59 2510 [Note] InnoDB: Initializing buffer pool, size = 128.0M2018-10-04 22:19:59 2510 [Note] InnoDB: Completed initialization of buffer pool2018-10-04 22:19:59 2510 [Note] InnoDB: The first specified data file ./ibdata1 did not exist: a new database to be created!2018-10-04 22:19:59 2510 [Note] InnoDB: Setting file ./ibdata1 size to 12 MB2018-10-04 22:19:59 2510 [Note] InnoDB: Database physically writes the file full: wait...2018-10-04 22:19:59 2510 [Note] InnoDB: Setting log file ./ib_logfile101 size to 48 MB2018-10-04 22:20:00 2510 [Note] InnoDB: Setting log file ./ib_logfile1 size to 48 MB2018-10-04 22:20:02 2510 [Note] InnoDB: Renaming log file ./ib_logfile101 to ./ib_logfile02018-10-04 22:20:02 2510 [Warning] InnoDB: New log files created, LSN=457812018-10-04 22:20:02 2510 [Note] InnoDB: Doublewrite buffer not found: creating new2018-10-04 22:20:02 2510 [Note] InnoDB: Doublewrite buffer created2018-10-04 22:20:02 2510 [Note] InnoDB: 128 rollback segment(s) are active.

看到有关./ib_logfie101的文件：进入到mysql的数据库目录下,删除这些ib开头文件(删除前建议先备份下,不然数据会丢失)；

[root@localhost_002 ~]# cd /data/mysql/[root@localhost_002 mysql]# ls aria_log_control ib_buffer_pool ib_logfile0 ib_logfile101 multi-master.info performance_schema aria_log.00000001 auto.cnf ibdata1 ib_logfile1 localhost_002.err mysql test[root@localhost_002 mysql]# rm -fr ib\_*[root@localhost_002 mysql]# rm -fr ibdata*[root@localhost_002 mysql]# /etc/init.d/mysqld startStarting MySQL.... SUCCESS! 

此时发现可以正常启动了：

查看下相关进程： ps aux |grep msyqld

[root@localhost_002 mysql]# ps aux |grep mysqldroot 2359 0.0 0.1 113308 1632 pts/0 S 22:19 0:00 /bin/sh /usr/local/mysql/bin/mysqld_safe --datadir=/data/mysql --pid-file=/data/mysql/localhost_002.pidmysql 2510 0.0 46.2 1305940 462072 pts/0 Sl 22:19 0:01 /usr/local/mysql/bin/mysqld --basedir=/usr/local/mysql --datadir=/data/mysql --plugin-dir=/usr/local/mysql/lib/plugin --user=mysql --log-error=localhost_002.err --pid-file=/data/mysql/localhost_002.pid --socket=/tmp/mysql.sockroot 2558 0.0 0.0 112720 972 pts/0 S+ 22:49 0:00 grep --color=auto mysqld