I have ran into a few projects using C where mmapped files over network mounts on windows were dropped in favor of a full read of the file in order to get the low level windows networking code to burst the file. In this case though your point may be true, I guess if the match happens randomly in the file there would be no need to have the whole file transfered across the network. I my cases I need access to the whole file every time. A good example between memmapped file access and a full open/read triggering the burst mode is simple though, copy with explorer almost always triggers the burst mode -- try installing ms office across a network drive ( the installer mmaps the cabs) time it, then time copying the files across and installing. Or a perl only test is a slurp and dump local vs line by line dump to local on a large text file. dws++ for bringing up a point I completly missed though.

Edited:
Also as far as I know the bursting mode does not work on samba servers as far as I know.

-Waswas