1、在LINUX6上安装 11.2.0.4的RAC，基本上不会遇到什么问题，但如果在LINUX7上安装11.2.0.4的RAC，经常性地会遇到问题。 为了很好地解决这个问题，ORACLE官方在MOS上给了一篇文档《Installation walk-through - Oracle Grid/RAC 11.2.0.4 on Oracle Linux 7 (Doc ID 1951613.1)》，这篇文档将LINUX7上安装11.2.0.4RAC可能会遇到的问题，以及对应的解决方案全部罗列了出来。
2、对于1951613.1这篇文档而言，最核心的一个补丁是18370031，在安装GI集群时，需要在运行root.sh之前先安装这个补丁，否则root.sh脚本必然会失败。
3、今天在测试环境中搭建一套LINUX7上的11.2.0.4RAC， 严格按照1951613.1这篇文档进行实施的，结果在运行root.sh时，仍然遇到故障，故障信息如下：
[root@11grac1 ~]# /u01/app/11.2.0.4/grid/root.sh
Performing root user operation for Oracle 11g
The following environment variables are set as:
ORACLE_OWNER= grid
ORACLE_HOME= /u01/app/11.2.0.4/grid
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 script.
Now product-specific root actions will be performed.
Using configuration parameter file: /u01/app/11.2.0.4/grid/crs/install/crsconfig_params
Creating trace directory
User ignored Prerequisites during installation
Installing Trace File Analyzer
OLR initialization - successful
root wallet
root wallet cert
root cert export
peer wallet
profile reader wallet
pa wallet
peer wallet keys
pa wallet keys
peer cert request
pa cert request
peer cert
pa cert
peer root cert TP
profile reader root cert TP
pa root cert TP
peer pa cert TP
pa peer cert TP
profile reader pa cert TP
profile reader peer cert TP
peer user cert
pa user cert
Adding Clusterware entries to oracle-ohasd.service
CRS-2672: Attempting to start 'ora.mdnsd' on '11grac1'
CRS-2676: Start of 'ora.mdnsd' on '11grac1' succeeded
CRS-2672: Attempting to start 'ora.gpnpd' on '11grac1'
CRS-2676: Start of 'ora.gpnpd' on '11grac1' succeeded
CRS-2672: Attempting to start 'ora.cssdmonitor' on '11grac1'
CRS-2672: Attempting to start 'ora.gipcd' on '11grac1'
CRS-2676: Start of 'ora.cssdmonitor' on '11grac1' succeeded
CRS-2676: Start of 'ora.gipcd' on '11grac1' succeeded
CRS-2672: Attempting to start 'ora.cssd' on '11grac1'
CRS-2672: Attempting to start 'ora.diskmon' on '11grac1'
CRS-2676: Start of 'ora.diskmon' on '11grac1' succeeded
CRS-2674: Start of 'ora.cssd' on '11grac1' failed
CRS-2679: Attempting to clean 'ora.cssd' on '11grac1'
CRS-2681: Clean of 'ora.cssd' on '11grac1' succeeded
CRS-2673: Attempting to stop 'ora.gipcd' on '11grac1'
CRS-2677: Stop of 'ora.gipcd' on '11grac1' succeeded
CRS-2673: Attempting to stop 'ora.cssdmonitor' on '11grac1'
CRS-2677: Stop of 'ora.cssdmonitor' on '11grac1' succeeded
CRS-2673: Attempting to stop 'ora.gpnpd' on '11grac1'
CRS-2677: Stop of 'ora.gpnpd' on '11grac1' succeeded
CRS-2673: Attempting to stop 'ora.mdnsd' on '11grac1'
CRS-2677: Stop of 'ora.mdnsd' on '11grac1' succeeded
CRS-5804: Communication error with agent process
CRS-4000: Command Start failed, or completed with errors.
CSS startup failed with return code 1
The exlusive mode cluster start failed, see Grid Infrastructure alert log for more information
Initial cluster configuration failed. See /u01/app/11.2.0.4/grid/cfgtoollogs/crsconfig/rootcrs_11grac1.log for details
[root@11grac1 ~]# /u01/app/11.2.0.4/grid/perl/bin/perl -I/u01/app/11.2.0.4/grid/perl/lib -I/u01/app/11.2.0.4/grid/crs/install /u01/app/11.2.0.4/grid/crs/install/rootcrs.pl execution failed
[root@11grac1 ~]#
4、MOS中找到文档《GI Intallation On Linux 7 Fails with 'CSS Startup Failed With Return Code 1' And CRS-1656 (Doc ID 2935061.1)》， 这篇文档中的故障现象与当前环境完全一致，最终 的解决方案是：安装补丁31718723 - 11.2.0.4.201020 (Oct 2020) Grid Infrastructure Patch Set Update (GI PSU) 。 之后 ，重新运行root.sh脚本。
5、 注意！！！ 我在测试环境中安装完补丁，重新运行root.sh，仍然报错，错误的现象与上述现象不同，怀疑是第一次运行root.sh脚本后，一些异常的配置信息影响了第二次root.sh。 最终的解决办法是运行deconfig脚本，将整个集群全部清空，然后运行config.sh脚本重新配置集群，此时运行root.sh脚本成功。