Use the natural ascending storage order whenever possible. This is column-major order, with the leftmost subscript varying fastest and striding by 1 (see Use Arrays Efficiently). If a program must read or write data in any other order, efficient block moves are inhibited.
If the whole array is not being written, natural storage order is the best order possible.
If you must use an unnatural storage order, in certain cases it might be more efficient to transfer the data to memory and reorder the data before performing the I/O operation.