在安裝好了MySQL之后，使用了新的配置文件后，MySQL服務器可以成功啟動，但在登陸的時候出現了ERROR 2002 (HY000): Can't connect to local MySQL server through socket，即無法通過socket連接到mysql服務器，同時提供了socket文件的位置。下面是這個問題的描述與解決辦法。
1、故障現象
[root@SZDB mysqldata]# mysql -uroot -p123456
Warning: Using a password on the command line interface can be insecure.
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/data/mysqldata/mysql.sock' (111)
#故障環境
[root@SZDB mysqldata]# more /etc/issue
CentOS release 5.9 (Final)
Kernel /r on an /m
2、故障分析
#查看mysql實例的狀態
[root@SZDB mysqldata]# netstat -ntlp | grep 3306
tcp 0 0 :::3306 :::* LISTEN 13001/mysqld
#查看my.cnf關于socket的配置
[root@SZDB mysqldata]# more /etc/my.cnf |grep sock
socket = /tmp/mysql.sock
#由上可知my.cnf中定義的為/tmp目錄下，而錯誤提示為/data/mysqldata/目錄下
#也就是說mysqld已經聲稱了正確的sock文件，但客戶端連接還是從初始目錄去找sock文件
#下面查看后臺日志，有個ERROR，是關于滿查詢日志的，是由于目錄不存在而產生的錯誤，與當前故障無關
[root@SZDB mysqldata]# more SZDB.err
............
2014-10-11 13:17:21 13001 [Note] InnoDB: 5.6.12 started; log sequence number 1625997
/app/soft/mysql/bin/mysqld: File '/log/mysql_logs/slowquery.log' not found (Errcode: 2 - No such file or directory)
2014-10-11 13:17:21 13001 [ERROR] Could not use /log/mysql_logs/slowquery.log for logging (error 2). Turning logging off for the who
le duration of the MySQL server process. To turn it on again: fix the cause, shutdown the MySQL server and restart it.
2014-10-11 13:17:21 13001 [Note] Server hostname (bind-address): '*'; port: 3306
2014-10-11 13:17:21 13001 [Note] IPv6 is available.
2014-10-11 13:17:21 13001 [Note] - '::' resolves to '::';
2014-10-11 13:17:21 13001 [Note] Server socket created on IP: '::'.
2014-10-11 13:17:21 13001 [Note] Event Scheduler: Loaded 0 events
2014-10-11 13:17:21 13001 [Note] /app/soft/mysql/bin/mysqld: ready for connections.
Version: '5.6.12-log' socket: '/tmp/mysql.sock' port: 3306 Source distribution
3、解決故障
a、通過配置my.cnf mysql選項socket文件位置解決
#先停止mysql服務器
[root@SZDB mysqldata]# service mysqld stop
Shutting down MySQL.[ OK ]
#修改my.cnf，如下
[root@SZDB mysqldata]# vi /etc/my.cnf
[mysql]
no-auto-rehash
socket = /tmp/mysql.sock #添加該行
#重啟mysql服務器
[root@SZDB mysqldata]# service mysqld start
Starting MySQL..[ OK ]
#再次連接正常
[root@SZDB mysqldata]# mysql -uroot -p
Enter password:
mysql> show variables like 'version';
+---------------+------------+
| Variable_name | Value |
+---------------+------------+
| version | 5.6.12-log |
+---------------+------------+
b、為socket文件建立鏈接方式
[root@SZDB mysqldata]# ln -s /tmp/mysql.sock /data/mysqldata/mysql.sock
ln: creating symbolic link `/data/mysqldata/mysql.sock' to `/tmp/mysql.sock': File exists
[root@SZDB mysqldata]# rm mysql.sock #上面提示文件存在，所以刪除之前的mysql.sock文件
[root@SZDB mysqldata]# ln -s /tmp/mysql.sock /data/mysqldata/mysql.sock
[root@SZDB mysqldata]# ls -hltr mysql.sock
lrwxrwxrwx 1 root root 15 Oct 11 14:00 mysql.sock -> /tmp/mysql.sock
[root@SZDB mysqldata]# mysql -uroot -p
Enter password:
mysql> show variables like 'socket';
+---------------+-----------------+
| Variable_name | Value |
+---------------+-----------------+
| socket | /tmp/mysql.sock |
+---------------+-----------------+
