在使用SSH方式配置RAC时，可能会在检查用户等价时失败。

配置了SSH之后，发现在验证用户等价时失败：

$ ./runcluvfy.sh comp nodecon -n ahrac1,ahrac2 -verbose

Verifying node connectivity

ERROR:
User equivalence unavailable on all the nodes.
Verification cannot proceed.

Verification of node connectivity was unsuccessful on all the nodes.

查询metalink发现是Oracle cluvfy工具的问题。Oracle在文章：Note:369598.1：User Equivalence Check Failed for User Oracle Using Ssh/scp中进行了详细的描述。

简单的说，Oracle在寻找ssh命令时，去/usr/local/bin目录下寻找，而ssh命令在/usr/bin目录下。

相应的解决方法也很简单，在/usr/local/bin目录下建立一个指向/usr/bin/ssh的链接就可以了。

root@ahrac1 # mkdir -p /usr/local/bin
root@ahrac1 # ln -s -f /usr/bin/ssh /usr/local/bin/ssh
root@ahrac1 # ln -s -f /usr/bin/scp /usr/local/bin/scp

不过再次尝试，仍然报错：

$ ./runcluvfy.sh comp nodecon -n ahrac1,ahrac2 -verbose

Verifying node connectivity

ERROR:
User equivalence unavailable on all the nodes.
Verification cannot proceed.

Verification of node connectivity was unsuccessful on all the nodes.

后来才发现，原来Oracle用户的ssh验证步骤必须先执行：

$ exec /usr/bin/ssh-agent $SHELL
$ /usr/bin/ssh-add
Enter passphrase for /export/home/oracle/.ssh/id_rsa:
Identity added: /export/home/oracle/.ssh/id_rsa (/export/home/oracle/.ssh/id_rsa)
Enter passphrase for /export/home/oracle/.ssh/id_dsa:
Identity added: /export/home/oracle/.ssh/id_dsa (/export/home/oracle/.ssh/id_dsa)
$ ./runcluvfy.sh comp nodecon -n ahrac1,ahrac2 -verbose

Verifying node connectivity

Checking node connectivity...

Interface information for node "ahrac2"
Interface Name IP Address Subnet
------------------------------ ------------------------------ -----------
ce0 172.25.198.43 172.25.0.0
ce0 172.25.198.45 172.25.198.0
ce1 10.0.0.4 10.0.0.0

Interface information for node "ahrac1"
Interface Name IP Address Subnet
------------------------------ ------------------------------ -----------
ce0 172.25.198.42 172.25.0.0
ce0 172.25.198.44 172.25.198.0
ce1 10.0.0.3 10.0.0.0

Check: Node connectivity of subnet "172.25.0.0"
Source Destination Connected?
------------------------------ ------------------------------ -----------
ahrac2:ce0 ahrac1:ce0 yes
Result: Node connectivity check passed for subnet "172.25.0.0" with node(s) ahrac2,ahrac1.

Check: Node connectivity of subnet "172.25.198.0"
Source Destination Connected?
------------------------------ ------------------------------ -----------
ahrac2:ce0 ahrac1:ce0 yes
Result: Node connectivity check passed for subnet "172.25.198.0" with node(s) ahrac2,ahrac1.

Check: Node connectivity of subnet "10.0.0.0"
Source Destination Connected?
------------------------------ ------------------------------ -----------
ahrac2:ce1 ahrac1:ce1 yes
Result: Node connectivity check passed for subnet "10.0.0.0" with node(s) ahrac2,ahrac1.

Suitable interfaces for the private interconnect on subnet "172.25.0.0":
ahrac2 ce0:172.25.198.43
ahrac1 ce0:172.25.198.42

Suitable interfaces for the private interconnect on subnet "172.25.198.0":
ahrac2 ce0:172.25.198.45
ahrac1 ce0:172.25.198.44

Suitable interfaces for the private interconnect on subnet "10.0.0.0":
ahrac2 ce1:10.0.0.4
ahrac1 ce1:10.0.0.3

ERROR:
Could not find a suitable set of interfaces for VIPs.

Result: Node connectivity check failed.

Verification of node connectivity was unsuccessful on all the nodes.

至此，问题得到解决。

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引自原文：http://yangtingkun.itpub.net/post/468/275147

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总结：个人安装的时候的问题

使用oracle 用户执行
cd /home/oracle/software/clusterware/cluvfy
./runcluvfy.sh comp nodereach -n rac1,rac2 -verbose   #1
./runcluvfy.sh stage -pre crsinst -n rac1,rac2        #2

执行第一句话的时候没有问题

但是在执行第二句话的时候出现了问题

Checking user equivalence...
    User equivalence check failed for user "oracle".       

Check failed on nodes:                                           

        rac1                                                                  
WARNING:                                                                  
User equivalence is not set for nodes:                    
        rac1                                                                 
Verification will proceed with nodes:             

    rac2                                                                 

于是按照上面的文档中的提示：

先在oracle用户下执行：

$ exec /usr/bin/ssh-agent $SHELL
$ /usr/bin/ssh-add

然后在执行第二句命令 ，然后顺利通过。