一台新虚拟机，CentOS 6.5系统，用lnmp一键安装包安装好Nginx + PHP环境，再安装Oracle客户端，准备搭建PHP连接Oracle，访问oracle.php，测试连接Oracle的时候，出错：
ORA-24408: could not generate unique server group name
度娘了好久，都说是主机名的事，但也都没有说明白原理，最后谷叔告诉我一个链接http://stackoverflow.com/questions/10484231/ora-24408-could-not-generate-unique-server-group-name
LZ也是遇到这样的问题，Camden S.给出的回答很详细：
You can downgrade to 10g if you want (it evidently doesn't care about this) but that's not necessary...
The 11g instant client requires a /etc/hosts file entry for your hostname pointing to 127.0.0.1. The normal "localhost" entry is not sufficient on it's own.
Assuming your host name is foomachine, there are two places you'll need to check:
In /etc/hosts, make sure you have any entry like - add it if it's not there:
127.0.0.1 foomachineAnd also make sure the /etc/sysconfig/network file also has
HOSTNAME=foomachine
That should do the trick.
这下就明白了，要在/etc/sysconfig/network中设置HOSTNAME，同时在/etc/hosts中保证127.0.0.1后面有刚才设置的HOSTNAME。
设置好以后重启系统，成功连接Oracle。
特此笔记，以免忘记。