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

    Date: Thu, 18 Jun 1992 08:30 PDT
    From: bill@cambridge.apple.com (Bill St. Clair)

    >Yes, FlushVol is the call you want. The problem exists even in System 6 with
    >the cache off, because there is a track cache anyway. This is documented in
    >a technote.
    >     Daniel.

    In 2.0b1p3 and later, FORCE-OUTPUT on an output file stream calls
    #_FlushFile. CLOSE calls #_FlushVol. The Inside Macintosh documentation
    for #_FlushFile says that "Some information stored on the volume won't
    be correct until PBFlushVol is called." Seems to me that FORCE-OUTPUT
    should do #_FlushFile, which it already does (in 2.0b1p3. 2.0b1 without
    patch 3 tried to do #_FlushVol, but neglected to put the volume number
    in the right place), and FINISH-OUTPUT should do #_FlushVol.

Gee, my interpretation is the FORCE-OUTPUT and FINISH-OUTPUT should do
the same amount of output flushing.  The difference is that
FINISH-OUTPUT should wait until the data is actually flushed out (if
possible) before returning, while FORCE-OUTPUT is allowed to "queue" a
flush request and return immediatly.  I don't think that FINISH-
should do a "harder" flush than FORCE-.