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From: simon@barnum.enet.dec.com (Curiosier and Curiosier...)
Newsgroups: comp.sys.ibm.pc
Subject: 286 Accelerator and Disk Interleave
Message-ID: <456@ryn.esg.dec.com>
Date: 13 Sep 89 20:19:55 GMT
Sender: guest@ryn.esg.dec.com
Organization: Digital Equipment Corporation
Lines: 50


Yesterday I installed a 12 MHz 286 accelerator (Orchid's Tiny Turbo XTra) 
into my 8 MHz XT.  The Norton SI went to 10.5 from 1.7, Landmark shows 
8.7 MHz.  These tests are recommended by the accelerator manual for 
installation verification and for comparison.  So far so good.  But running 
some real application I noticed a considerable slow down from a disk (so 
considerable, in fact, that it was practically intolerable).  Ran SI again, 
this time with a disk performance.  It was 0.5 of XT!  Before the accelerator 
installation it was 2.

The disk drive is a 72 Mb Maxtor 2085.  The low level format was done with 
interleave factor 3.  FDISK from Compaq MS-DOS 3.31 partitioned it into 
two partitions, 1 (C:) and 2, 2 being logically divided into drives D: and 
E:.

I ran a SPINTEST (shareware) on drive 1 only.  With the original 8088 
it was around 200,000 bit/sec.  With the 286 I got only 30,000.  An HDTEST 
(also shareware) showed two drives, 0 and 1.  Interleave measurement showed 
that changing it from 3 to 5 would increase the performance by around 300%.
I did, and the SPINTEST indicated the rate of around 100,000.  Running 
an application I got a feeling that the speed was satisfactory.

I went back to the SPINTEST, to test drive 2.  It bounced me back to DOS 
with a message:  "System error".  I went to the HDTEST and tried to change 
the interleave.  HDTEST can do it without destroying the data.  However, 
it gave me an error message ("seek failure" for some cylinders, "format 
error" for others).  Eventually I aborted it.

Now with only disk 1 re-formatted the performance is at best acceptable, 
but I would like to get the previous 200,000 bit per sec.

A few questions that I have:

1.	Was it normal that the disk performance changed so drastically 
because of an accelerator?

2.	What is this System Error?

3.	What should I do to fix it?

4.	Is a radical measure necessary such as doing a low level format 
again?

5.	How can I change the interleave on the drive 2?

Any help will be appreciated.
---
Leo Simon	simon@hpstek.enet.dec.com
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