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From: ejp@bohra.cpg.oz.au (Esmond Pitt)
Newsgroups: comp.os.os2.misc
Subject: Re: Disk buffering
Message-ID: <1991May1.021720.20381@bohra.cpg.oz.au>
Date: 1 May 91 02:17:20 GMT
References: <WEISS.91Apr29221914@toucan.lcs.mit.edu>
Distribution: comp
Organization: Software Division, Computer Power Group
Lines: 50

In article <WEISS.91Apr29221914@toucan.lcs.mit.edu> weiss@theory.lcs.mit.edu (Paul G. Weiss) writes:
> Can anyone explain the difference between the various forms of
> disk buffering available under OS/2?  In particular, what is the
> difference between:
>
>     (a) The BUFFERS parameter in CONFIG.SYS?

These are used when doing disk reads & writes of blocks that do not
occupy an entire sector.

>     (b) The DISKCACHE parameter in CONFIG.SYS?

I believe this applies to the FAT file system.

>     (c) The /c switch in installing HPFS?

Applies to HPFS only; must be used in assocation with a RUN=CACHE
statement.

I have:

	IFS=C:\OS\HPFS.IFS /C:256 /AUTOCHECK:F
	RUN=C:\OS2\CACHE.EXE /LAZY:ON

See the description of BUFFERS, DISKCACHE, IFS and CACHE in the online
command reference.

>
> How do these affect operation of
>
>     (a) A FAT fixed disk filesystem
>     (b) A HPFS fixed disk filesystem

Make them faster, as appropriate.

>     (c) A floppy disk filesystem

No effect.

> Also, what if anything does all this have to do with machines that are
> advertising as having a disk controller with a built-in cache.

Nothing. If the disk controller has a large built-in cache you should
not need much in the way of software caching as per DISKCACHE and
HPFS /C:


-- 
Esmond Pitt, Computer Power Group
ejp@bohra.cpg.oz