The following error is reported trying to create a Physical Standby database using "duplicate from active database" : RMAN-: ===========================================================
RMAN-: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-: ===========================================================
RMAN-: failure of Duplicate Db command at // ::
RMAN-: error occurred in stored script. Memory Script
RMAN-: failure of backup command on disk1 channel at // ::
ORA-: Oracle error returned by remote Oracle server
问题处理：
最初是以为db_file_name_convert参数设置有问题，但是详细验证后，并没有发现问题。
最后发现，在standby库中在创建对应目录stdby的时候，手误写成了stdy
重新创建正确的目录后，再执行duplicate命令时，执行成功。