The following error is reported trying to create a Physical Standby database   using "duplicate from active database" :RMAN-00571: ===========================================================RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============RMAN-00571: ===========================================================RMAN-03002: failure of Duplicate Db command at 05/10/2015 19:54:23RMAN-03015: error occurred in stored script. Memory ScriptRMAN-03009: failure of backup command on disk1 channel at 05/10/2015 19:54:23ORA-17628: Oracle error 19505 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。