[oracle@edgzrip1-PROD1 admin]$ rman target sys/oracle auxiliary sys/oracle@dg

Recovery Manager: Release 11.2.0.3.0 - Production on Sat May 4 10:02:37 2019

Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved.

connected to target database: PROD1 (DBID=2223214796)

connected to auxiliary database: DG (not mounted)

RMAN> RUN { 

DUPLICATE TARGET DATABASE

  FOR STANDBY

  FROM ACTIVE DATABASE

  DORECOVER

  SPFILE

     parameter_value_convert 'PROD1','DG'

    SET "db_unique_name"="DG" ;

}

2> 3> 4> 5> 6> 7> 8> 9> 

Starting Duplicate Db at 04-MAY-19

using target database control file instead of recovery catalog

allocated channel: ORA_AUX_DISK_1

channel ORA_AUX_DISK_1: SID=20 device type=DISK

RMAN-00571: ===========================================================

RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============

RMAN-00571: ===========================================================

RMAN-03002: failure of Duplicate Db command at 05/04/2019 10:02:44

RMAN-05501: aborting duplication of target database

RMAN-05541: no archived logs found in target database

原因：

出现这种错误很可能是你刚刚将主数据库切换为归档模式然后紧接着就利用RMAN的duplicate创建standby数据库导致的。原因就在于主数据库切换为归档模式之后还未发生过切换，手动在主数据库上切换一次就可以了

SQL> alter system switch logfile;

System altered.

再次执行复制成功