Path: utzoo!attcan!uunet!cs.utexas.edu!tut.cis.ohio-state.edu!bgsuvax!denbeste
From: denbeste@bgsuvax.UUCP (William C. DenBesten)
Newsgroups: comp.sys.mac
Subject: Re: RAM cache size
Message-ID: <4178@bgsuvax.UUCP>
Date: 25 May 89 14:20:26 GMT
References: <11353@netnews.upenn.edu>
Organization: Bowling Green State University B.G., Oh.
Lines: 26

From article <11353@netnews.upenn.edu>, by rubinoff@linc.cis.upenn.edu (Robert Rubinoff):
> I have also been having problems that I think are caused by the RAM cache.
> Does anyone know what it actually caches, and whether it's write-through?
> ...
> It's nice to get the speedup the cache gives, but not at the risk of losing
> files (or corrupting the disk directory).  Does anyone know if there is a safe
> size to set the cache that will prevent this?  

For the complete scoop on caching on the macintosh, check out
Macintosh Technical note # 81.

The control panel cache is not write-through.  Apple recommends (in
MTN 81) that programmers call FlushVol() after writing a file to the
disk.  I always harp on users not to use a paper clip indiscriminately
and to always pull shutdown before they turn off their machine.

I have empirically found that setting the cache at 32K is best.  Using
no cache is much slower, and I do not notice significant improvement
with a larger cache.  A smaller cache will also reduce the amount of
stuff that you can have waiting to be written to disk, so it will
reduce your chances of damage in a crash.  

-- 
 William C. DenBesten
 denbeste@bgsu.edu
denbesten@bgsuopie.bitnet