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From: karl@robot.in-berlin.de (Karl-P. Huestegge)
Newsgroups: comp.periphs.scsi,comp.unix.sysv386,comp.unix.xenix.sco
Subject: Re: Low disk throughput on Xenix 2.3.2/1542B/wren V
Message-ID: <1991Mar16.065105.7871@robot.in-berlin.de>
Date: 16 Mar 91 06:51:05 GMT
References: <1991Mar15.055352.20092@simasd.uucp>
Distribution: comp
Organization: K.-P. Huestegge, Sytemanalyse und Beratung, Berlin
Lines: 44

jcurtis@baron..uucp (Jay Curtis) writes:
>	I am having a problem with SCO Xenix 2.3.2GT and very low disk
>transfer rates.  Here is my configuration:

>Adaptec 1542B DMA=5 irq=11 i/o base=330, bios enabled, 5 Meg DMA
>	transfer rate
>Wren V 330 Meg SCSI drive
>Archive 2150S tape drive

>With this config, I am only able to get 124K Bytes/sec. throughput under
>Xenix.  Under Dos I get 496 K Bytes/sec.  Under ISC Unix, similar rates
>to Dos.  Is there a known problem with the scsi drivers under Xenix?

Well, you should get 960 KB/s under DOS, 700 KB/s under tuned ISC Unix 
(remember they have a fast-filesystem) and > 400KB/s under tuned Xenix.

Did you enable Synchronous Negotiation on the Host Adapter and the
Drives (close jumper 5 Pin 1) ? 
Did you enable Parity on all Devices (open pin3 jumper 5 on the Host Adapter)?

First test it under DOS with the GREAD.EXE-Utility from Adaptec 
(uucp-download from adaptex).

With plain xenix you should get 290 KB/s on your Wren V.

Then tune the xenix kernel with adb to optimize the boson/bosoff times of
the scsi-transfer (you can get the recipe per uucp from adaptex 'sco.patch').

Or do:
adb -w /xenix ; tune the DMA speed to a higher value 'ad_xfer /b' returns
0 (=5MB/s). Set it to 4(=5.7MB/s), 1(6.7MB/s) or 2(8MB/s) with the command
'ad_xfer /w 1'. 
'ad_buson/b' returns a value of 5. Set it to 8-10 ('ad_buson/w 8').
'ad_busoff/b' returns a value of 7. Set it to 4 ('ad_busoff/w 4').
exit adb with '$w' '$q'.

>(please say yes...please!!)

yes.

-- 
Karl-Peter Huestegge                            karl@robot.in-berlin.de
Berlin Friedenau                                Bus: 2,25,48,81,85
U-Net: Bhf.F.Wilh.Pl.                           ..unido!fub!geminix!robot!karl