问题：
在这里 DB DG 切换，发现一个问题，主库A的模式切换到备库模式 时候，该主库日志会有如下提示：
ORA-17627: ORA-01017: invalid username/password; logon denied
ORA-17629: Cannot connect to the remote database server
检查：
1． 经过检查，发现该报错来自于rman@pdbdb03 (TNS V1-V3） 进程
*** MODULE NAME:(rman@pdbdb03 (TNS V1-V3)) 2020-06-08 01:31:36.843
krsd_get_primary_connect_string
询问了，备份是跑数据库 A 上，备份也是正常的， 说明这个报错不会影响备份。
2． 经过分析，应该是触发了一个bug Bug 17580082 - ACTIVE STANDBY - RMAN-06820: WARNING: FAILED TO ARCHIVE CURRENT LOG AT PRIMARY
Status: 32 - Not a Bug. To Filer
在11.2 环境下，如果rman 备份发生在备库，oracle 会强制主库做一个switch logfile 操作。如果连不上主库，就会触发这个报错。
as of 11.2.0.4, we now include the current standby redo log as part of an RMAN archivelog backup at the standby site. This is achieved by forcing a log switch at the primary site.
规避方法：
1。如果备份 发起在 容灾库备份，备份脚本 使用用户名+ 密码方式登录。
Instead put in the username and password for the SYSDBA user:
$ rman target sys/password@stby
而不是That is, do not use just the "/" (operating system authentication) connect to the standby database: 这样会导致 备库的备份连接不到主库，产生这个报错的
$ rman target /
2。这个Bug Bug 21476308/17580082 在如下版本得到修复，12.1.0.2.170117 (Jan 2017) Database Patch Set Update (DB PSU)
ORA-1017 by RMAN When Connecting to Target with Username/Password from RMAN Operations Platforms affected Generic (all / most platforms affected)
Fixed:
12.2.0.1 (Base Release)
12.1.0.2.170117 (Jan 2017) Database Patch Set Update (DB PSU)
（Enhancement Request/Bug 18070699 allows for the use of other
user/password apart from sys password to connect to remote database for RMAN
operation.
Bug 18070699: ALLOW NON-SYS USERNAME GRANTED SYSDBA TO
RESYNC DB_UNIQUE_NAME ALL
Patches are available for this issue by searching bug 21476308 for patch name or number. ）