在windows客户端sqlplus工具使用VIP或scan的IP无法连接，报错如下：
C:\Users\WJW>sqlplus system/qweasd@192.168.2.200:1521/orcl
SQL*Plus: Release 11.2.0.1.0 Production on Thu May 17 12:35:28 2012
Copyright (c) 1982, 2010, Oracle. All rights reserved.
ERROR:
ORA-12545: Connect failed because target host or object does not exist
检查各组件状态，正常,TNSPING也是通的
原因：
metalink说明：Client is able to resolve all Fully Qualified Domain Name (FQDN) SCAN and VIP name but not short ones(without domain name) as its in different domain;
even though FQDN names were specified during Grid Infrastructure setup, due to bug 9150053 by default DBCA set database parameter local_listener to short node VIP name
while database is created.
因此只要把数据库实例参数local_listener内的host改为vip的IP地址即可
解决办法：
rac1:
SQL> show parameter local_listener
NAME TYPE VALUE
local_listener string (DESCRIPTION=(ADDRESS_LIST=(AD
DRESS=(PROTOCOL=TCP)(HOST=rac1
-vip)(PORT=1521))))
SQL> alter system set local_listener='(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.2.111)(PORT=1521))))' scope=both sid='orcl1';
SQL> alter system register;
rac2:
SQL> show parameter local_listener
NAME TYPE VALUE
local_listener string (DESCRIPTION=(ADDRESS_LIST=(AD
DRESS=(PROTOCOL=TCP)(HOST=rac2
-vip)(PORT=1521))))
SQL> alter system set local_listener='(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.2.112)(PORT=1521))))' scope=both sid='orcl2';
SQL> alter system register;
随后使用windows客户端连接成功：
C:\Users\WJW>sqlplus system/qweasd@192.168.2.200:1521/orcl
SQL*Plus: Release 11.2.0.1.0 Production on Thu May 17 13:14:39 2012
Copyright (c) 1982, 2010, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Data Mining and Real Application Testing options
另外解决Oracle 11gR2 RAC 无法在客户端通过scanIP连接数据库
安装完Oracle 11g rac后，在10g的客户端的 tnsnames.ora中配置好，scanip,但是无法访问，报错为目标主机不存在，折腾了很久，没弄明白，后面查到，系统初始化参数里有local_listener这一项，在这里可以对host的值加以修改，将scanip注册进来、在监听器中使用vip！
在racnode1服务器上：
root@racdb1 \~# su - oracle
oracle@racdb1 \~$ sqlplus /nolog
SQL*Plus: Release 11.2.0.1.0 Production on Wed Apr 21 13:44:12 2010
Copyright (c) 1982, 2009, Oracle. All rights reserved.
SQL> conn /as sysdba
Connected.
SQL> show parameter local_listener;
NAME TYPE VALUE
local_listener string (DESCRIPTION=(ADDRESS_LIST=(AD
DRESS=(PROTOCOL=TCP)(HOST=rac1_vip)(PORT=1521))))
设置
SQL> alter system set local_listener='(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=racscan)(PORT=1521))))' scope=both sid='racdb1';
System altered.
SQL>
节点二上面也是，一样的修改。