Path: utzoo!utgpu!water!watmath!focsys!larry
From: larry@focsys.UUCP (Larry Williamson)
Newsgroups: comp.unix.microport
Subject: BellTech's floppy speed improvement
Summary: use interleave of 2 not 4 to speed up the floppy access
Keywords: interleave floppy slow speed
Message-ID: <158@hocus.focsys.UUCP>
Date: 27 Jul 88 15:28:32 GMT
Organization: Focus Automation Systems, Waterloo, Ont.
Lines: 31


The poor performance of the Bell Technologies floppy driver can be somewhat
overcome if one formats the floppies with an interleave of 2 rather than
the default 4.

I ran a couple of very simple tests with interleaves of 4, 3, 2 and 1. I
would format the floppy, and then

	find tmp-dir -print | cpio -ovc >/dev/rdsk/f0q15dt

where tmp-dir contained 10 files totaling about 327K

The timex results were:

	interleave	time
	    4           50.77
            3           43.02
            2           36.14
            1         1:55.19

Caveat: This test was definitely non-exhaustive.  But it did indicate a
definite trend.  I only tested write times and this with cpio.  Read
times, tar and mounted file systems will possibly be different.  You
might like to do some test of your own. 

I'm sure that the type of floppy controller will affect your results somewhat.

The system that I'm using is a 16Mhz Intel motherboard with a Western Digital
RA2 controller

Larry