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From: tholen@uhccux.uhcc.hawaii.edu (David Tholen)
Newsgroups: comp.os.os2
Subject: HPFS
Keywords: OS/2, memory, cache
Message-ID: <5652@uhccux.uhcc.hawaii.edu>
Date: 8 Dec 89 06:41:25 GMT
Organization: University of Hawaii
Lines: 27

I recently installed OS/2 version 1.2 on my machine, choosing to use HPFS
rather than FAT for the hard disk.  Given that HPFS uses its own cache, is
it superfluous to allocate additional memory for similar disk-related
activities with the CONFIG.SYS statements BUFFERS and DISKCACHE?  The answer
is not immediately obvious; for example, an 80486 coupled with an external
cache does seem to improve performance over and above what the internal cache
provides, but I'm not certain the analogy is appropriate in this case, given
that the functions of BUFFERS and DISKCACHE are different (that is, maybe
only one of the two is superfluous when using HPFS).  I suppose I could
learn the answer the hard way:  lots of test runs.  But rebooting that many
times doesn't sound like fun, and I'm currently running a VERY long
background job, so I won't be in a position to try for a while.  I thought
perhaps someone out there might already know the answer and could save me
some time.

The improvement in disk performance is quite noticeable, except in one or two
recent cases which I'm guessing were slowed down by the need to swap a lot
of memory to disk in order to load a big program.  That's my problem:  I have
less free memory under 1.2 than I did with 1.1, and I'm trying to find ways
to conserve.  Eliminating the memory allocated to DISKCACHE would help a lot,
but with BUFFERS=30, the memory consumption is only about 15 kbytes, so that
wouldn't help much.

Please e-mail responses to:  tholen@uhccux.uhcc.hawaii.edu
Thanks in advance.

--Dave Tholen