While it's a couple of weeks old, in case it hasn't been seen by "those
who need it", the folllowing thread on linux kernel discusses the
fsync-and-IDE-writecache interactions. There is also a comment on MacOS
X - I have no idea if that was already known, but I thought it might be
worth pointing out.
http://www.uwsg.iu.edu/hypermail/linux/kernel/0403.2/0527.html
//Magnus
