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From: terry@cs.weber.edu (A Wizard of Earth C)
Subject: Re: Elusive SCSI problems (Adaptec 1542C) <snarl!>
Message-ID: <1993May12.205857.8857@fcom.cc.utah.edu>
Keywords: Adaptec 1542C, Quantum, SCSI, 386bsd
Sender: news@fcom.cc.utah.edu
Organization: Weber State University (Ogden, UT)
References: <1993May12.023959.20121@sophia.smith.edu>
Date: Wed, 12 May 93 20:58:57 GMT
Lines: 53
In article <1993May12.023959.20121@sophia.smith.edu> jfieber@sophia.smith.edu (J Fieber) writes:
>SETTING:
> A UM486V AIO motherboard --
> - 33MHz 80486dx
> - 6 ISA, 2 VL-bus slots
> - 256k external cache
> - local-bus IDE controller w/ connor 240 meg drive
> - floppy controller
> - 2 serial, 1 parallel, 1 game port
> - AMI bios
HOW MUCH RAM? You imply 8M; if >16, there will be problems. Reduce to
16M or below and retry.
> It does not always fail. For example, several hours last night every
> thing worked without a single error. However, the *only* pattern
> I have been able to detect is that it works consistantly good or
> bad in any one session (i.e. it will work okay but if I reboot,
> then it will not work at all until I reboot again at which point
> who knows what it will do?!). It seems as though something that
> happens at boot time determines the reliability of the SCSI system.
[ ... ]
[ BUS ON TIMES ]
> Would some kernel hacker tell me how to adjust this properly?)
[ ... ]
>ADAPTEC CONFIG:
This is where you diddle tyhe bus-on times. Unless you have recompiled
the kernel, you will have a hard time reducing bus-on time. I believe
that someone else had this problem (Nate?) and it's now working for him
with about a 50% reduction in on time.
The problem in his case was that the DMA refresh wasn't getting done.
You may want to jumper more wait states onto the motherboard to see if
this will help. If the wait states do the trick, you should be able
to load and recompile with your now heavily-sedated machine. If adding
wait states doesn't help, then it'd not the bus-on time.
Also: who is the manufacturer of your extern cache silicon? I probably
won't be able to identify a bad manufacturer without going through all
the old postings, but someone else might. There *are* known problems
with some chips.
Terry Lambert
terry@icarus.weber.edu
---
Any opinions in this posting are my own and not those of my present
or previous employers.
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