Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!ssc-vax!shuksan!tahoma!prl3546
From: prl3546@tahoma.UUCP (Philip R. Lindberg)
Newsgroups: comp.sys.apple
Subject: Re: SCSI TIMER & V5.0
Message-ID: <593@tahoma.UUCP>
Date: 29 Aug 89 16:47:02 GMT
References: <707@mountn.dec.com>
Organization: The Boeing Co., BCA FSL, Seattle, WA
Lines: 52

From article <707@mountn.dec.com>, by shatara@memit.dec.com (Chris Shatara):
> # 
> ## I have already optimized the interleave under V4.0 with a 40% improvement 
> ## in read times and was wondering if the interleave should change because 
> ## of the SCSI driver improvements in System 5.0
> # 
> #When you reran these and got a 40% improvement was it because you changed
> #the interleaf?  (Or maybe it was because of the driver/ADU improvements in

		^^^^^^	I wrote this question.  ^^^
 
> The improvement was from the interleave. The reason I say this Is that I 
> ran the disk for a month under V4.0 BEFORE I got a copy of SCSI hacker and 
> Timer.  I never ran the hard disk under System software V3.2.

I'm sorry, I'm still confused.  Does this mean you didn't format your
drive originally to the optimum interleaf using a SCSI Timer (or compat.)???
Therefore, your improvement was from doing this?

> I just finish this procedure again with new system disk.  As before I ran 
> a while with the old interleave settings and by changing them was able to 
> reduce the read times by another 15% (according to SCSI timer). 

When you say "old interleaf settings" do you mean "the Apple defined"
settings?  (ie. 1:1 or 1:2) Or do you mean "your previously optimized"
settings?  (ie. optimized at, say, 9 with 4.0, and now 5 with 5.0)

> Interesting enough the docs which came with SS 5.0 suggested 1:1 or 1:2 as 
> an interleave setting (infact the software would use one of these settings 
> if you allowed it to do the low level format)  I ended up with a setting 
> of 5.  (4 gave me the lowest setting and 5 gave me some margine for 
> tolerances).  I am running with an Apple SCSI board and a SEAGATE st138N 
> drive.

The Apple doc.'s suggestion really only apply to APPLE's stuff.  Any one with
a third party drive (including homebrew) must use the optimum for their
config.  The third party manufacturers figure this out for you.  If you
have a homebrew, you need to do it yourself.

(Note:  the Seagate ST138N is a fast 30 meg. drive.  If you ran with Apple's
default interleaf it's no wonder you got a big improvement.)
 
> /chris
 
+---------------------------------------------------------+
|	     The Apple //'s will live forever!!		  |
|  Phil Lindberg	    snail mail: 13845 S.E. 131 ST |
| INET: prl3546@tahoma.UUCP		Renton, WA 98056  |
| UUCP: ..!uw-beaver!ssc-vax!shuksan!tahoma!prl3546	  |
|    Disclaimer: I don't speak for my employer (and I not |
|		 sure they even know I exist....)	  |
+---------------------------------------------------------+