Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!ut-emx!allred
From: allred@ut-emx.UUCP (Kevin L. Allred)
Newsgroups: comp.sys.ibm.pc
Subject: Re: IBM/SCSI
Summary: ST02 not the problem --- 500 KBPS still possible.
Message-ID: <20406@ut-emx.UUCP>
Date: 2 Nov 89 21:06:27 GMT
References: <5862@shlump.nac.dec.com>
Distribution: na
Organization: UT-Austin, Dept. of Chem. Engr
Lines: 47

In article <5862@shlump.nac.dec.com>, mattioli@TOOK.DEC.COM (John R. Mattioli) writes:
> 	I now find that I have a scsi controler and drive (st02 controler and
> 80meg seagate drive).  I ran norton si on it (under dos) and the disk index (di)
> number it returned was 0.6!  Someone PLEASE tell me I can do better by tweeking
> my controler or my drive somehow!  Why spend all this money to get performence
> like 28msec access time when the disk really isn't all that great after all? 
> 
> 	What is the best thing for those of us with an st02 (or st01) to do?

You're not in as bad a shape as you think.  What you need to do is
backup all the information you have put on you hard disk, and do a low
level format using Diskmanager in manual mode. (/m switch I believe).
Select the format menu. If you are running on a 286 or 386 of at least
8+ Mhz you should find the optimal format to be a 2:1 interleve.
Repartition and test the speed with coretest or spintest (don't trust
Norton Si).  If the speed is 400 to 500 KBPS, go ahead and restore
your files.  If the speed much lower, try a low level format with 3:1
interleve, and so on until you hit the best combo.  Don't be overly
conserned about the time to reformat.  My experience was that at 2:1
interleve, a complete reformat took about 10 minutes.  Backup, on the
otherhand, takes time.

1:1 interleve used to be possible, but Seagate screwed that up for the
Mac's sake (1:1 is too fast for a Mac+).  Your drive is probably
formatted now for 1:1 interleve, which is really screwing transfers
up.  On my system the transfer rate went from about 50 KBPS to 500
KBPS when I went from 1:1 interleve to 2:1 interleve.  Just so you
won't feel bad, 2:1 interleve on an ST296N is as fast as 1:1 interleve
on an ST4096 (Don't forget, the ST296N/ST02 is also about $150 cheaper
than the ST4096/WD1006 etc.).  This has to do with the number of
sectors per track (34 vs 17).  A more expencive host addaptor isn't
going to help you any, the problem is the BIOS on the ST296N.
Following this proceedure, you should see much better performance.

Now a word to the wise...

Memory is cheap again; so adding 1MB of RAM to your system to
dedicate to disk caching or RAM disk is going to be much cheaper, and
give you much more performance for you money, than a more expensive
disk and controller.  If you get a high cache hit rate, the actual
speed of the media is not very important.

-- 

	Kevin Allred
	allred@emx.cc.utexas.edu
	allred@ut-emx.UUCP