I work mainly on Windows and Windows CE based systems, where CreateFile, ReadFile and WriteFile are the work horses, no matter if I'm in native Win32 land or in managed .Net land.

I have so far never had any obvious problem writing or reading big files in one chunk, as opposed to looping until several smaller chunks are processed. I usually delegate the IO work to a background thread that notifies me when it's done.

But looking at file IO tutorials or "textbook examples", I often find the "loop with small chunks" used without any explanation of why it's used instead of the more obvious (I dare to say!) "do it all at once".

Are there any drawbacks to the way I do that I haven't understood?