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From: rex@cs.su.oz (Rex Di Bona)
Newsgroups: comp.sys.mips
Subject: Re: Problems with external SCSI devices on RC3240
Message-ID: <2265@cluster.cs.su.oz.au>
Date: 5 Apr 91 03:59:18 GMT
Article-I.D.: cluster.2265
References: <1991Apr4.220929.3759@bcl.co.nz>
Sender: news@cluster.cs.su.oz.au
Reply-To: rex@cluster.cs.su.oz (Rex Di Bona)
Organization: Basser Dept of Computer Science, University of Sydney, Australia
Lines: 54

In article <1991Apr4.220929.3759@bcl.co.nz> chris@bcl.co.nz (Chris Mackerell) writes:
> Has anyone experienced problems running multiple external SCSI
> peripherals off RC3240 or M120 machines?
> 
> We have three systems here (2 x RC3240, 1 x M120) that seem to be
> incapable of handling more than one external SCSI peripheral. An RS2030
> system handles the same peripherals with no problems.

We have four M120's and a RC3240, each having external peripherals.
The longest string of peripherals we have had would be the internal
drive and tape, two external drives (wrens) and an exabyte. - Worked fine!

> There is little in common between the systems. (Different customers, sites
> and peripherals).
 
I'm sorry, what is your involvment with the machines? Are you a support
group or what? Were all the machine purchased from the same supplier?
When were the machine purchased?

> It doesn't seem to matter what peripherals are used (we've tried
> combinations of Wren drives, Maxtor drives, 8mm tapes and cartridge
> tapes), or what order they are connected.

Ok, silly question time:
1) Did all the devices have different SCSI addresses?
2) Did you do an 'sprobe' command (boot sash and type 'sprobe')
	This will list what devices the machine can see on the SCSI buss.
3) Do you have any problems with the INTERNAL devices? Is there an internal
	drive and tape?
 
> We've swapped the motherboard on one RC3240, which improved things but
> hasn't cured the problem entirely.

In what way did things improve?

> The symptoms vary with the number of devices attached, varying from
> failing the SCSI power on diags (with serveral devices attached), to
> the occasional recovered SCSI error (with one attached).
> 
> Has anyone else experienced problems similar to this? Is there a cure?

My vote would go for either bad cables or connectors. Have you tried
new SCSI cables? The SCSI connectors on the back of our M120 expansion
cabinet were thought to be dodgy, and we did get the symptoms you
described. The connector wasn't making a good connection. We would get
soft errors, and the occasional hard error. If all the machines were
purchased from the same supplier (and about the same time) then that
would be a similarity between them.

Once we got that fixed we had no problem with the bus (although any
non-standard peripherals still wouldn't work :-)
--------
Rex di Bona (rex@cs.su.oz.au)
Penguin Lust is NOT immoral