? disk writes actually done or still just in the cache ?

[cdj@tc.pw.com]

Could someone contribute as to when data written to disk actually gets
there verses just being queued in the Macintosh cache?  I have a
prototype that, when it crashes "just right", seems to have completed
a recent disk write operation but not another one that had preceded it.
(My disk writes are in the form of toolbox calls.)

In Macintosh system 6, one could turn off the cache mechanism and
seemingly avoid this trouble, but with system 7 the cache is always
enabled.  IM doesn't seem illuminating on when writes can be assured
of having physically completed and I see my prototype does sometimes get
it wrong as things are now.  There is a volflush call but no description
that assures me it really does what I want.  (I'm using MACL 2.0f if
that matters here.)

Thanks,
Cris Johnson 
Price Waterhouse Technology Centre 
68 Willow Road, Menlo Park, CA 94025 
(415) 322-0606