Re: scsi-problem (phase change ?)

Hauke Johannknecht (
Sun, 22 Jun 1997 20:16:10 +0200 (MET DST)

On Sun, 22 Jun 1997, Gerard Roudier wrote:

> > makes a total of no more than 2 meters ...
> Perhaps a little more, since if the external box has 2 connectors, the
> internal cable length should be about 80 cms.
already included this part... the internal cable in the
main-box is a cut-of-after-the-last-connector type ... :)

> The Ultra drive has probably been tested only with Ultra SCSI compliant
> SCSI stuff.
it should be hard for it to run at ultra ... with my ncr 810 ...

> Looks like a
> ShouldWorkInTheoryButMayHaveEveryChanceToGetProblemsScsiSystem (TM). :)
resmile ...

> 1 - Seems you are'nt sure internal terminators are active.
yop. the termis on the Quantum are the plug-in-the-arrays
type. seems to be passive.

> If the DCRS has terminators, they probably are active ones and
> you could use them instead.
nope. the DCRS has no termination-option. this is the only
reason for keeping the quantum. i have to terminate the
bus somehow. :(

> Are you sure all devices, including the controller, that shall not be
> terminated are correctly configured with terminations disabled.
smile. i can read. i can set jumpers. i hate pay-n-pray.
i am quite sure.

> 2 - You are using internal and external devices. Such configuration is
> sensitive to cable quality.
cabling is standard out-of-the-shop 7-devices-1,5-meters stuff ...
cut of after the last needed connector with a sharp knife.

> Forget 'add-single-device', unless you are sure that the device you
> switch on/off while the SCSI lines are driven does behave correctly
> in regard of SCSI lines when it is switched on/off.
i am quite sure.
no probs near the switch-it-on time ... they
just happen lots of time later.

> Since you probably are'nt quite sure of that, you should only switch
> boxes in that order, in my opinion:
> 1 - switch on the external box, then switch on the system box.
> 2 - switch off the system box, then switch off the external box.
jup. i am doing this. the external box got two additional switches
for killing 5-and-12-lines on the ST41600N and the hp6020i
(whose switch is not involved in the problem !)

> > > > (can an overheated hdd data-kill another one via the scsi-bus ?)
> > > Since the SCSI bus is a shared resource, any device on the bus can
> > > make the resource unusable.
> > i guess a scsi-bus-testing-device costs more than a new harddisk ? :)
> I donnot understand the joke, unless my obvious answer was not clear.
> An overheated hdd is more usable for frying eggs that to shared a SCSI
> bus, if you see what I mean. :)
uh. the "joke" was that i would like to keep the 1,3 GB
old-and-loud seagate for mass-storage. 1,3 GB == 2 iso-images ... :)
but if it is bus-confusing, then i will throw it as far
as i can. (not far. 5,25" full height.) but i can not be
quite sure without a test-the-bus-device. but this device
would surely cost more than a new harddisk. so i will
throw away the ST anyways ... :) ... got it ?

> > smile, i would like to use a 3940, if you give me one for free ... :)
> Using 2 NCR53C810 controllers offers also 2 SCSI buses for far less
> money.
i think about including my old-but-working Future Domain
TMC-950. should work for controlling the ST ...

> > i think my bus is ok, just the drive drives it crazy ...
> Seems that only a single response was acceptable for you.
> Bad spot for me! I'm not been able to guess it. I will try to do better
> next time. :)
sorry. my primary problem is that i dont know much about
scsis inner workings. so i did not understand the
"phase-change"-message. and because of the "not-so-standard"
ncr-driver i asked here. i allways ask here if i dont
know what my system is doing to me. :)

Mucho gracias for your FAST help.


Hauke Johannknecht     
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