RHEL 7.5中安装11gRAC时，在grid infrastructure的root.sh执行时，报错：
# /oracle/product/11g/grid/root.sh ... Adding Clusterware entries to inittab ohasd failed to start Failed to start the Clusterware. Last 20 lines of the alert log follow: 2019-01-04 17:02:36.004: [client(25743)]CRS-2101:The OLR was formatted using version 3.
这是由于RHEL 7改变了init的管理方式，出现了兼容性上的问题。官方给出了补丁18370031，在PSU 28429134也有包含,选择一个就好。
具体的处理方式为：
1、首先deinstall掉grid
$ORACLE_HOME/deinstall/deinstall
按照提示进行
2、按照常规步骤进行安装
3、在弹出root执行脚本时注意，先执行orainstRoot.sh，暂时先暂停
4、解压OPatch和补丁包
5、创建opatch 的ocmrf，但选择不启用
$ $ORACLE_HOME/OPatch/ocm/bin/emocmrsp -no_banner -output /oracle/ocm.rsp Provide your email address to be informed of security issues, install and initiate Oracle Configuration Manager. Easier for you if you use your My Oracle Support Email address/User Name. Visit http://www.oracle.com/support/policies.html for details. Email address/User Name: <----直接回车 You have not provided an email address for notification of security issues. Do you wish to remain uninformed of security issues ([Y]es, [N]o) [N]: Y The OCM configuration response file (/oracle/ocm.rsp) was successfully created.
6、打补丁18370031
$ /oracle/product/11g/grid/OPatch/opatch napply -oh /oracle/product/11g/grid -local /home/grid/18370031 -ocmrf /oracle/ocm.rsp Oracle Interim Patch Installer version 11.2.0.3.20 Copyright (c) 2019, Oracle Corporation. All rights reserved. ... OPatch succeeded.
7、再执行root.sh
# /oracle/product/11g/grid/root.sh ... Adding Clusterware entries to oracle-ohasd.service CRS-2672: Attempting to start 'ora.mdnsd' on 'rac01' CRS-2676: Start of 'ora.mdnsd' on 'rac01' succeeded CRS-2672: Attempting to start 'ora.gpnpd' on 'rac01' CRS-2676: Start of 'ora.gpnpd' on 'rac01' succeeded CRS-2672: Attempting to start 'ora.cssdmonitor' on 'rac01' CRS-2672: Attempting to start 'ora.gipcd' on 'rac01' CRS-2676: Start of 'ora.cssdmonitor' on 'rac01' succeeded CRS-2676: Start of 'ora.gipcd' on 'rac01' succeeded CRS-2672: Attempting to start 'ora.cssd' on 'rac01' CRS-2672: Attempting to start 'ora.diskmon' on 'rac01' CRS-2676: Start of 'ora.diskmon' on 'rac01' succeeded CRS-2676: Start of 'ora.cssd' on 'rac01' succeeded ASM created and started successfully. Disk Group GRID created successfully. ... Configure Oracle Grid Infrastructure for a Cluster ... succeeded