RMAN-06478: datafile copy 'string' cannot be found on disk
Cause: The CHANGE DATAFILECOPY AVAILABLE command was used, but the datafilecopy cannot be found on disk.
Action: If the storage containing the datafilecopy has been removed from the host, then restore it and retry the command. If the datafilecopy is permanently gone, then issue the CHANGE DATAFILECOPY DELETE command for this datafile.