环境：
Oracle 11.2.0.3 + OEL 7.9
A -> B -> C 级联ADG环境：db11g -> db11gadg -> db11gcas
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of Duplicate Db command at 05/14/2023 23:54:15
RMAN-05501: aborting duplication of target database
RMAN-05531: a mounted database cannot be duplicated while datafiles are fuzzy
客户确认是从一级备库duplicate到二级备库OK，查询文档：
- RMAN Duplicate From Active Database Fails when Source Database is Standby and Patch 11715084 Applied (Doc ID 1522062.1)
为了避免更多杂七杂八的bug，我决定应用11.2.0.3版本最后的PSU（Patch Set Update）；
- Assistant: Download Reference for Oracle Database/GI Update, Revision, PSU, SPU(CPU), Bundle Patches, Patchsets and Base Releases (Doc ID 2118136.2)
定位到 11.2.0.3最后一个PSU是：p20996944_112030_Linux-x86-64.zip
- Patch 20996944 - Oracle Grid Infrastructure Patch Set Update 11.2.0.3.15 (Jul2015) (Includes Database PSU)
这里想多聊下关于readme，但凡是有经验的DBA，都知道打补丁要看对应的readme，而不是直接上去就操作，虽然打补丁流程类似，但也会有个别补丁之间存在差异，按readme指引操作才是最靠谱的。
Document 854428.1 Patch Set Updates for Oracle Products
This document includes the following sections:
Section 2, "Patch Installation and Deinstallation"
Section 4, "References"
Section 6, "Bugs Fixed by This Patch"
我们需要下载OPatch Utility，通过 6880880 搜索：
- You must use the OPatch utility version 11.2.0.3.5 or later to apply this patch.
我们知道utility software通常是指最基础的系统工具软件，而Opatch 这种软件用于打各种版本的PSU补丁，所以称之为Opatch utility就容易理解了。
另外值得一提的是，像SUV这种耳熟能详的汽车车型，其中的U也是Utility这个词哦（Sport Utility Vehicle），这样是不是一下子就记住了呢～
- The OPatch utility will prompt for your OCM (Oracle Configuration Manager) response file when it is run.
OCM response file is required and is not optional.
在readme中针对比如手工应用等章节是指向到具体的MOS文档进一步说明：
- Readme - Patch Installation and Deinstallation For 11.2.0.3.x GI PSU (Doc ID 1494646.1)
嗯，在应用之前，再去duplicate尝试下，确定目前是有问题的。
将级联备库db11gcas对应的实例启动到nomount状态；然后执行脚本报错：
sh dup_dg.sh
...
RMAN-05531: a mounted database cannot be duplicated while datafiles are fuzzy
在db11gadg备库先应用PSU补丁，更新OPatch Utility版本然后应用补丁：
[oracle@db11gadg media]$ $ORACLE_HOME/OPatch/opatch version
Invoking OPatch 11.2.0.1.7
OPatch Version: 11.2.0.1.7
OPatch succeeded.
需要更新OPatch Utility，下载最新的11.2.0.3.41 尝试?
记得太新的其实未必兼容，另外目前连接实验环境没有多少流量可用传输。
所以从实验环境的本地网盘上搜到，p6880880_112000_Linux-x86-64_11.2.0.3.12.zip。
也符合要求。
[oracle@db11gadg dbhome_1]$ pwd
/u01/app/oracle/product/11.2.0/dbhome_1
[oracle@db11gadg dbhome_1]$ unzip /u01/media/p6880880_112000_Linux-x86-64_11.2.0.3.12.zip
[oracle@db11gadg dbhome_1]$ $ORACLE_HOME/OPatch/opatch version
OPatch Version: 11.2.0.3.12
OPatch succeeded.
解压补丁，应用DB补丁：
建立一个空文件夹，解压：
[oracle@db11gadg media]$ mkdir tmp
[oracle@db11gadg media]$ unzip p20996944_112030_Linux-x86-64.zip -d ./tmp/
[oracle@db11gadg tmp]$ pwd
/u01/media/tmp
[oracle@db11gadg tmp]$ ls -lrth
total 220K
-rw-r--r-- 1 oracle oinstall 21 Jan 9 2014 README.txt
-rw-r--r-- 1 oracle oinstall 0 Jan 9 2014 atp_lfp
drwxr-xr-x 5 oracle oinstall 44 Jan 9 2014 17592127
drwxrwxr-x 17 oracle oinstall 4.0K Jun 9 2015 20760997
-rw-r--r-- 1 oracle oinstall 450 Jun 9 2015 bundle.xml
-rw-rw-r-- 1 oracle oinstall 63K Jul 14 2015 README.html
-rw-rw-r-- 1 oracle oinstall 143K Jul 14 2015 PatchSearch.xml
关闭数据库，监听，应用补丁；
SQL> shutdown immediate
[oracle@db11gadg 20760997]$ lsnrctl stop
[oracle@db11gadg 20760997]$ $ORACLE_HOME/OPatch/opatch apply
Email address/User Name: <--- 直接回车！
You have not provided an email address for notification of security issues.
Do you wish to remain uninformed of security issues ([Y]es, [N]o) [N]: Y <--- Y表示 希望不了解安全问题，不然就一直让你输入邮箱..
Please shutdown Oracle instances running out of this ORACLE_HOME on the local system.
(Oracle Home = '/u01/app/oracle/product/11.2.0/dbhome_1')
Is the local system ready for patching? [y|n]
y <--- y表示本地环境已经准备好应用补丁了！
...
Composite patch 20760997 successfully applied.
OPatch Session completed with warnings.
Log file location: /u01/app/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/opatch2023-05-22_15-17-55PM_1.log
OPatch completed with warnings.
应用完补丁查询：
[oracle@db11gadg 20760997]$ $ORACLE_HOME/OPatch/opatch lsinventory
...
OPatch succeeded.
启动监听和数据库：
$ lsnrctl start
SQL> startup
然后级联备库再次发起duplicate操作，不再报错了哈～
这里先应用一个备库，就是为了验证这个问题是否能修复。