MySQL server PID file could not be found! 

无法启动mysql服务

# service mysqld start

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

Starting MySQL...The server quit without updating PID file [FAILED]ydata/centossz008.pid).

通过ss -tnl发现服务仍然存在

服务假死，强行将服务停用

# killall mysqld

重启

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock'

查看mysql数据目录权限是否正常

# chown -R mysql.mysql /data