Thanks David, thanks for your excellent explanation. 
2009/1/24 David Craig
> I would say that comment is misleading at best. I would say ‘cannot’ is
> probably best replaced with ‘should not’. At the storage stack, no driver
> knows that the read or write requests being processed are for a file that
> is
> not buffered. That also doesn’t include controllers and/or drives that
> contain internal caches where Windows has no way to tell those devices not
> to cache data.
>
> Now as to your question, look at CreateFile in user land. Read the
> restrictions on block and offset values. Allowing append data would
> require
> that the file end at the correct boundary, so I guess they don’t permit
> them
> to be combined.
>
> wrote in message news:xxxxx@ntfsd…
> > Hi, guys.
> >
> > I read this from wdk document:
> >
> > “FILE_NO_INTERMEDIATE_BUFFERING :
> > The file cannot be cached or buffered in a driver’s internal buffers.
> > This flag is incompatible with the DesiredAccess FILE_APPEND_DATA flag.”
> >
> > Why is these two flags incompatible?
> >
> > Thanks in advance!
> >
>
>
>
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