"cannot obtain %s enqueue for datafile %s"
*Cause: The file access enqueue could not be obtained for a file
specified in a backup, copy or restore operation.
If the enqueue type shown is 'shared', then the file is the
input file for a backup or copy. If the type is 'exclusive', then
the file is the output file for a datafile copy or restore which
is attempting to overwrite the currently active version of that
file - in this case, the file must be offline or the database must
be closed. If the type is 'read-only', then you are attempting
to back up or copy this file while the database is in NOARCHIVELOG
*Action: Wait until the conflicting operation is complete, then retry
the copy or backup. If the database is in NOARCHIVELOG mode, then
all files being backed up must be closed cleanly.