Backups to tape can only be backup sets. use rman

摘自oracle官方rman 手册才发现默认只能把备份集到磁带
Backup sets can be created on disk, or on media manager devices such as tape drives.
When the AS COPY option is used, RMAN generates image copies of the input files. An image copy is a byte-for-byte identical copy of the original file. You can create image copy backups of datafiles, datafile copies, and archived redo log files. Image copy files can only exist on disk.
You can create and restore image copy backups with RMAN, or with a native operating system command for copying files. However, when you use RMAN to create image copies, they are recorded in the RMAN repository, and are more easily available for use in restore and recovery operations. Otherwise, you must use the CATALOG command to add the image copies to the RMAN repository before RMAN can use them.
By default, RMAN creates all backups as backup sets, on tape or on disk. You can change the default backup type for disk backups to be image copies using the CONFIGURE command. Backups to tape can only be backup sets.