Linux: Visualize writes to a file
Solution 1:
Seekwatcher uses blktrace underneath and can provide you all kinds of information about disk activity. It can analyze existing blktrace dump files or start blktrace for you. Seekwatcher is probably not exactly what you are looking for, but maybe it can serve as a starting point.
Also look for blktrace analyzers, perhaps there are others lurking somewhere out there. +1 for interesting question, anyway!