"unable to encrypt backup"
*Cause: RMAN could not create an encrypted backup. This message will
be accompanied by other messages that give more details about
why the encrypted backup could not be created. The most common
reason for this message is that you are trying to create a
backup that can be transparently decrypted, and the database
external security device is not open.
*Action: If the external security device is not open, then open it.
If the external security device is not configured, then the
only type of encrypted backup that you can create is a