1：配置新节点操作系统环境同其他节点一致，包括共享存储，补丁包，内核参数，用户环境变量等等
[root@rac3 ~]# cat /etc/hosts
127.0.0.1               localhost.localdomain localhost
192.168.1.41            rac1.yang.com      rac1
192.168.122.41          rac1-priv.yang.com rac1-priv
192.168.1.141           rac1-vip.yang.com  rac1-vip

192.168.1.42            rac2.yang.com      rac2
192.168.122.42          rac2-priv.yang.com rac2-priv
192.168.1.142           rac2-vip.yang.com  rac2-vip

192.168.1.43            rac3.yang.com      rac3
192.168.122.43          rac3-priv.yang.com rac3-priv
192.168.1.143           rac3-vip.yang.com  rac3-vip

[root@rac3 ~]# getenforce 
Disabled
[root@rac3 ~]# groupadd  oinstall
[root@rac3 ~]# groupadd dba
[root@rac3 ~]# useradd -g oinstall -G dba oracle
[root@rac3 ~]# echo 'oracle' |passwd --stdin oracle
Changing password for user oracle.
passwd: all authentication tokens updated successfully.

[root@rac3 ~]# tail /etc/sysctl.conf 
kernel.shmall = 2097152  
kernel.shmmax = 2147483648    
kernel.shmmni = 4096    
kernel.sem = 250 32000 100 128    
fs.file-max = 65536    
net.ipv4.ip_local_port_range = 1024 65000    
net.core.rmem_default = 262144    
net.core.rmem_max = 262144    
net.core.wmem_default = 262144    
net.core.wmem_max = 262144    
[root@rac3 ~]# sysctl -p

[root@rac3 ~]# tail -4  /etc/security/limits.conf 
oracle soft nproc 2047  
oracle hard nproc 16384  
oracle soft nofile 1024  
oracle hard nofile 65536

[root@rac3 ~]# tail -1 /etc/pam.d/login 
session    required     pam_limits.so
 
[root@rac3 ~]# tail -1 /etc/modprobe.conf
options hangcheck-timer hangcheck_tick=30 hangcheck_margin=180

[root@rac3 ~]# modprobe -v hangcheck-timer  
insmod /lib/modules/2.6.9-89.EL/kernel/drivers/char/hangcheck-timer.ko hangcheck_tick=30 hangcheck_margin=180

2：在新节点上配置共享存储，创建相关目录，设置用户环境变量
[root@rac3 ~]# chown -R oracle.oinstall /u01/
[root@rac3 ~]# su - oracle
[oracle@rac3 ~]$ cat .bash_profile 
# .bash_profile  
# Get the aliases and functions  
if [ -f ~/.bashrc ]; then  
         . ~/.bashrc  
fi  
 
PATH=/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/usr/X11R6/bin:/root/bin:/root/bin  
export EDITOR=vim 
export ORACLE_SID=racdb3 
export ORACLE_BASE=/u01/app/oracle  
export ORACLE_HOME=$ORACLE_BASE/product/10.2.0/db_1  
export ORA_CRS_HOME=$ORACLE_BASE/product/10.2.0/crs_1  
export LD_LIBRARY_PATH=/lib  
alias sqlplus='/usr/local/rlwrap/bin/rlwrap sqlplus' 
alias rman='/usr/local/rlwrap/bin/rlwrap rman' 
export NLS_DATE_FORMAT='YYYY-MM-DD HH24:MI:SS' 
export NLS_LANG=american_america.UTF8  
export PATH=$ORACLE_HOME/bin:$ORA_CRS_HOME/bin:$PATH
umask 022  
[oracle@rac3 ~]$ mkdir -p  $ORACLE_BASE/admin
[oracle@rac3 ~]$ mkdir -p  $ORACLE_HOME
[oracle@rac3 ~]$ mkdir -p  $ORA_CRS_HOME 

3：配置各个节点的ssh对等性
[oracle@rac3 ~]$ ssh-keygen  -t dsa
[oracle@rac3 ~]$ ssh-keygen  -t rsa
使用ssh-copy-id命令将rac3节点的公钥导入到rac1,rac2上的/home/oracle/.ssh/authorized_keys文件中，步骤不在赘述；
最终需要实现在3个节点上使用oracle用户进行相互ssh登陆不需要输入密码

 [oracle@rac1 ~]$ crs_stat -t -v
Name           Type           R/RA   F/FT   Target    State     Host        
----------------------------------------------------------------------
ora....SM1.asm application    0/5    0/0    ONLINE    ONLINE    rac1        
ora....C1.lsnr application    0/5    0/0    ONLINE    ONLINE    rac1        
ora.rac1.gsd   application    0/5    0/0    ONLINE    ONLINE    rac1        
ora.rac1.ons   application    0/3    0/0    ONLINE    ONLINE    rac1        
ora.rac1.vip   application    0/0    0/0    ONLINE    ONLINE    rac1        
ora....SM2.asm application    0/5    0/0    ONLINE    ONLINE    rac2        
ora....C2.lsnr application    0/5    0/0    ONLINE    ONLINE    rac2        
ora.rac2.gsd   application    0/5    0/0    ONLINE    ONLINE    rac2        
ora.rac2.ons   application    0/3    0/0    ONLINE    ONLINE    rac2        
ora.rac2.vip   application    0/0    0/0    ONLINE    ONLINE    rac2        
ora.racdb.db   application    0/1    0/1    ONLINE    ONLINE    rac1        
ora....b1.inst application    0/5    0/0    ONLINE    ONLINE    rac1        
ora....b2.inst application    0/5    0/0    ONLINE    ONLINE    rac2

[oracle@rac1 ~]$ cd $ORA_CRS_HOME/oui/bin
[oracle@rac1 bin]$ ./addNode.sh

 查看日志信息
[oracle@rac1 ~]$ tail -f  /u01/app/oracle/oraInventory/logs/addNodeActions2011-11-29_09-42-48PM.log
INFO: /u01/app/oracle/product/10.2.0/crs_1/oui/bin/../bin/runInstaller  -paramFile /u01/app/oracle/product/10.2.0/crs_1/oui/bin/../clusterparam.ini  -silent

-ignoreSysPrereqs -updateNodeList -noClusterEnabled ORACLE_HOME=/u01/app/oracle/product/10.2.0/crs_1 CLUSTER_NODES=rac1,rac2,rac3 CRS=true 

"INVENTORY_LOCATION=/u01/app/oracle/oraInventory" LOCAL_NODE=rac3 -remoteInvocation -invokingNodeName rac1 -logFilePath "/u01/app/oracle/oraInventory/logs"

-timestamp 2011-11-29_09-42-48PM
INFO: OUI-10234:Failed to copy the root script, /u01/app/oracle/oraInventory/orainstRoot.sh to the cluster nodes rac3.
Please copy them manually to these nodes and execute the script

[oracle@rac1 ~]$ scp  /u01/app/oracle/oraInventory/orainstRoot.sh rac3:/u01/app/oracle/oraInventory/

 运行相关脚本：
[root@rac3 ~]# /u01/app/oracle/oraInventory/orainstRoot.sh
Changing permissions of /u01/app/oracle/oraInventory to 770.
Changing groupname of /u01/app/oracle/oraInventory to oinstall.
The execution of the script is complete

[root@rac1 ~]# /u01/app/oracle/product/10.2.0/crs_1/install/rootaddnode.sh
clscfg: EXISTING configuration version 3 detected.
clscfg: version 3 is 10G Release 2.
Attempting to add 1 new nodes to the configuration
Using ports: CSS=49895 CRS=49896 EVMC=49898 and EVMR=49897.
node <nodenumber>: <nodename> <private interconnect name> <hostname>
node 3: rac3 rac3-priv rac3
Creating OCR keys for user 'root', privgrp 'root'..
Operation successful.
/u01/app/oracle/product/10.2.0/crs_1/bin/srvctl add nodeapps -n rac3 -A rac3-vip/255.255.255.0/eth0:eth1 -o /u01/app/oracle/product/10.2.0/crs_1

[root@rac3 ~]# /u01/app/oracle/product/10.2.0/crs_1/root.sh
WARNING: directory '/u01/app/oracle/product/10.2.0' is not owned by root
WARNING: directory '/u01/app/oracle/product' is not owned by root
WARNING: directory '/u01/app/oracle' is not owned by root
WARNING: directory '/u01/app' is not owned by root
WARNING: directory '/u01' is not owned by root
Checking to see if Oracle CRS stack is already configured
/etc/oracle does not exist. Creating it now.
OCR LOCATIONS =  /dev/raw/raw5,/dev/raw/raw6
OCR backup directory '/u01/app/oracle/product/10.2.0/crs_1/cdata/crs' does not exist. Creating now
Setting the permissions on OCR backup directory
Setting up NS directories
Oracle Cluster Registry configuration upgraded successfully
WARNING: directory '/u01/app/oracle/product/10.2.0' is not owned by root
WARNING: directory '/u01/app/oracle/product' is not owned by root
WARNING: directory '/u01/app/oracle' is not owned by root
WARNING: directory '/u01/app' is not owned by root
WARNING: directory '/u01' is not owned by root
clscfg: EXISTING configuration version 3 detected.
NO KEYS WERE WRITTEN. Supply -force parameter to override.
-force is destructive and will destroy any previous cluster
configuration.
Oracle Cluster Registry for cluster has already been initialized
Startup will be queued to init within 90 seconds.
Adding daemons to inittab
Expecting the CRS daemons to be up within 600 seconds.
CSS is active on these nodes.
        rac1
        rac2
        rac3
CSS is active on all nodes.
Oracle CRS stack installed and running under init(1M)
Running vipca(silent) for configuring nodeapps
The given interface(s), "eth0" is not public. Public interfaces should be used to configure virtual IPs.

最后需要在rac3节点上使用root用户手动运行下$ORA_CRS_HOME/bin/vipca

[oracle@rac2 ~]$ crs_stat -t -v
Name           Type           R/RA   F/FT   Target    State     Host        
----------------------------------------------------------------------
ora....SM1.asm application    0/5    0/0    ONLINE    ONLINE    rac1        
ora....C1.lsnr application    0/5    0/0    ONLINE    ONLINE    rac1        
ora.rac1.gsd   application    0/5    0/0    ONLINE    ONLINE    rac1        
ora.rac1.ons   application    0/3    0/0    ONLINE    ONLINE    rac1        
ora.rac1.vip   application    0/0    0/0    ONLINE    ONLINE    rac1        
ora....SM2.asm application    0/5    0/0    ONLINE    ONLINE    rac2        
ora....C2.lsnr application    0/5    0/0    ONLINE    ONLINE    rac2        
ora.rac2.gsd   application    0/5    0/0    ONLINE    ONLINE    rac2        
ora.rac2.ons   application    0/3    0/0    ONLINE    ONLINE    rac2        
ora.rac2.vip   application    0/0    0/0    ONLINE    ONLINE    rac2        
ora.rac3.gsd   application    0/5    0/0    ONLINE    ONLINE    rac3        
ora.rac3.ons   application    0/3    0/0    ONLINE    ONLINE    rac3        
ora.rac3.vip   application    0/0    0/0    ONLINE    ONLINE    rac3        
ora.racdb.db   application    0/1    0/1    ONLINE    ONLINE    rac1        
ora....b1.inst application    0/5    0/0    ONLINE    ONLINE    rac1        
ora....b2.inst application    0/5    0/0    ONLINE    ONLINE    rac2

[oracle@rac2 ~]$ olsnodes -n
rac1    1
rac2    2
rac3    3

[root@rac3 ~]# /u01/app/oracle/product/10.2.0/db_1/root.sh
Running Oracle10 root.sh script...

The following environment variables are set as:
    ORACLE_OWNER= oracle
    ORACLE_HOME=  /u01/app/oracle/product/10.2.0/db_1

Enter the full pathname of the local bin directory: [/usr/local/bin]: 
   Copying dbhome to /usr/local/bin ...
   Copying oraenv to /usr/local/bin ...
   Copying coraenv to /usr/local/bin ...

Creating /etc/oratab file...
Entries will be added to the /etc/oratab file as needed by
Database Configuration Assistant when a database is created
Finished running generic part of root.sh script.
Now product-specific root actions will be performed.