答案不能

主库执行duplicate过程中
RMAN>duplicate target database for standby from active database dorecover nofilenamecheck;

主库查询视图提示备库NOT MOUNT?
SQL> select dest_id,error from v$archive_dest;
   DEST_ID ERROR
---------- -----------------------------------------------------------------
         1
         2 ORA-16058: standby database instance is not mounted
其实DG库在duplicate过程中就已经mount成功，DG库无法接受主库归档，原因如下RFS进程无法启动！

Completed: alter database clear logfile group 3
RFS connections are allowed

 只有在备库接受所有主库网络远程发送的数据文件之后，DG库进行clear logfile之后，才允许RFS启动！！！所以造成duplicate主库无法传送归档至备库

Mon Mar 02 01:05:44 2020
RFS[1]: Assigned to RFS process 17430
RFS[1]: Opened log for thread 1 sequence 2585 dbid 1969706720 branch 1008014307
Mon Mar 02 01:05:44 2020
RFS[2]: Assigned to RFS process 17428
RFS[2]: Opened log for thread 1 sequence 2586 dbid 1969706720 branch 1008014307
Archived Log entry 1 added for thread 1 sequence 2585 rlc 1008014307 ID 0x7590229f dest 2:
Archived Log entry 2 added for thread 1 sequence 2586 rlc 1008014307 ID 0x7590229f dest 2:
RFS[2]: Opened log for thread 1 sequence 2587 dbid 1969706720 branch 1008014307
Archived Log entry 3 added for thread 1 sequence 2587 rlc 1008014307 ID 0x7590229f dest 2:
Mon Mar 02 01:05:45 2020
Primary database is in MAXIMUM PERFORMANCE mode
RFS[3]: Assigned to RFS process 17436
RFS[3]: No standby redo logfiles created
RFS[3]: Opened log for thread 1 sequence 2588 dbid 1969706720 branch 1008014307