mysql 无法登陆

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)

检查配置文件/etc/my.cnf发现供应商修改了mysql数据库的数据存储目录，另外mysql.sock文件位置也变更为了/dat/data/mysql/mysql.sock

$ more /etc/my.cnf

# For advice on how to change settings please see

# http://dev.mysql.com/doc/refman/5.6/en/server-configuration-defaults.html

[mysqld]

#

# Remove leading # and set to the amount of RAM for the most important data

# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.

# innodb_buffer_pool_size = 128M

innodb_buffer_pool_size = 2048M

#

# Remove leading # to turn on a very important data integrity option: logging

# changes to the binary log between backups.

# log_bin

#

# Remove leading # to set options mainly useful for reporting servers.

# The server defaults are faster for transactions and fast SELECTs.

# Adjust sizes as needed, experiment to find the optimal values.

# join_buffer_size = 128M

# sort_buffer_size = 2M

# read_rnd_buffer_size = 2M

#datadir=/var/lib/mysql

#socket=/var/lib/mysql/mysql.sock

datadir=/dat/data/mysql

socket=/dat/data/mysql/mysql.sock

# Disabling symbolic-links is recommended to prevent assorted security risks

symbolic-links=0

# Recommended in standard MySQL setup

sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES 

[mysqld_safe]

log-error=/var/log/mysqld.log

pid-file=/var/run/mysqld/mysqld.pid

检查发现/var/lib/mysql.sock文件不存在，可以通过建立mysql.sock文件的软连接。然后登录数据库，问题解决。

[root@GETAZLNX005 ~]# ls /var/lib/mysql.sock

ls: cannot access /var/lib/mysql.sock: No such file or director

[root@GETAZLNX005 ~]# ln -s /dat/data/mysql/mysql.sock /var/lib/mysql/mysql.sock
今天在那做实验倒腾MySQL数据库，后来发现服务无法启动，查看日志报错如下：
2015-01-07 17:48:54 9136 [ERROR] InnoDB: .\ibdata1 can't be opened in read-write mode2015-01-07 17:48:54 9136 [ERROR] InnoDB: The system tablespace must be writable!2015-01-07 17:48:54 9136 [ERROR] Plugin 'InnoDB' init function returned error.2015-01-07 17:48:54 9136 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.2015-01-07 17:48:54 9136 [ERROR] Unknown/unsupported storage engine: InnoDB2015-01-07 17:48:54 9136 [ERROR] Aborting
解决方法：
1、打开任务管理器终止mysqld进程；
2、打开mysql安装目录的data文件夹，删除以下2个文件：
ib_logfile0和ib_logfile1

3、重新启动mysql