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From: ephraim@wang.UUCP (pri=8 Ephraim Vishniac x76659 ms1459)
Newsgroups: net.micro.mac
Subject: Re: Mac Cache
Message-ID: <842@wang.UUCP>
Date: Thu, 24-Jul-86 08:11:52 EDT
Article-I.D.: wang.842
Posted: Thu Jul 24 08:11:52 1986
Date-Received: Fri, 25-Jul-86 21:31:25 EDT
References: <932@hounx.UUCP>
Organization: Wang Labs, Lowell MA
Lines: 20

> There has been plenty of talk about setting the cache on the Mac +,
> but I haven't heard any mention of the proper way to turn off your
> Mac when the cache is enabled. I have had some file changes blown
> away when I powered down after using a program. 
> 
> Does anyone know the best way to write the cache to disk so that a
> safe power down is possible. 
> 
The best way is to choose "Shut Down" from the Finder.  This flushes
and ejects every mounted volume.  The other advantage to exiting via
Shut Down (instead of, say, by hitting reset) is that the file system
sets a flag on HFS disks to indicate that they're in a consistent 
state.  This saves a lot of time when the volume is next mounted, as
it does some automatic recovery on potentially inconsistent volumes.

Programming note:  it recently occurred to me that programs that do
direct disk I/O (such as full-disk backup programs, or FEdit) could
be tripped up by the cache.  I asked MacTech how to flush the cache,
and they replied that _FlushVol forced write-through from the cache
to the indicated volume.