linux采用rpm方式安装mysql，默认都装到根目录下了，需要将其安装路径挪到/data目录；

迁完后Mysql启动时候报告错误，找不到pid文件

[root@testdb2 oracle]# service mysql start

Starting MySQL..Manager of pid-file quit without updating file.[FAILED]

此时需要采用safe模式启动

[root@testdb2 oracle]# which mysqld_safe

/usr/bin/mysqld_safe

[root@testdb2 oracle]# /usr/bin/mysqld_safe --user=mysql&

[1] 7301

[root@testdb2 oracle]# 110801 15:33:40 mysqld_safe Logging to '/var/lib/mysql/testdb2.err'.

110801 15:33:40 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql

此时可以登录mysql

[root@testdb2 oracle]# mysql

Welcome to the MySQL monitor.  Commands end with ; or \g.

Your MySQL connection id is 1

Server version: 5.1.51 MySQL Community Server (GPL)

Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.

This software comes with ABSOLUTELY NO WARRANTY. This is free software,

and you are welcome to modify and redistribute it under the GPL v2 license

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> exit

Bye