At 21:41 01/10/03, Ray New wrote:
>I have a WDE9100W SCSI drive connected the wide channel
>(68 pin) on a 2940UW and an Iomega internal SCSI ZIP on
>the narrow (50 pin) channel. I get the message
>"Insufficient termination on the wide channel" during
>boot up, yet both drives are terminated and function
>normally. The termination on the drive is set in software
>as "automatic".
Hi Ray
I'm a bit confused by your statement that termination is set
on the WD drive via software. Do you mean that you are using
SCAM (SCSI plug and play)? (To use this, you would have to have
a jumper (shunt) set across (connecting) pins 17 and 18 of the
WD9100 drive's jumper block.
<http://www.pcguide.com/ref/hdd/if/scsi/confSCAM-c.html> says
"While a great idea in theory, SCAM never lived up to its
potential. The main issue with the feature is that it doesn't
always work reliably--it's not a simple matter to automatically
assign device IDs or figure out which devices should enable
termination. Many people would find that they needed to disable
the feature and manually configure drives to eliminate problems.
There were also difficulties if devices supporting SCAM were
mixed with other devices that did not support the feature.
Eventually, hardware makers started recommending that people
avoid the feature altogether and just configure devices manually,
reasoning that this would reduce the likelihood of problems. And
let's be honest--it doesn't take that long to set the IDs of a
few devices, and you typically only have to do it once anyway."
"SCAM was eventually removed from the SCSI parallel interface
standard."
In my experience, termination for any SCSI device is best set
via the device's on-board jumpers.
Here's what I would do:
Set the SCSI ID of the WD drive to ID=0. (Verify that there
are no jumpers on pins 1 through 8.) I assume you already
set the ID on the IOMEGA ZIP drive (by jumper) to some number
between 1 and 6. (If not, do so.) The Adaptec 2940UW should
automatically be ID=7.
Have termination ENABLED (via jumper) on the internal narrow
SCSI IOMEGA ZIP drive.
Have termination ENABLED on the WD wide SCSI hard drive
(put a jumper across pins 23 and 24). "Termpower" for
the WD drive can be set as either ON or OFF.
For the Adaptec 2940UW, you should have termination set
for either "Low OFF, High ON" or "Automatic". (In a perfect
world, if you set the controller for "Automatic", the 2940UW
will sense that it needs to be set for "low off, high on"
and will make that setting automatically.) Hit the "Control"
and "A" keys simultaneously immediately as you see the
Adaptec banner display as your computer boots.
[*] The high byte (of the SCSI bus) is terminated at the WD
drive and at the 2940UW controller. The low byte is
terminated at the WD drive and at the ZIP drive. (A wide
SCSI bus is two bytes wide...which are called the low byte
and the high byte. A narrow SCSI bus has only the low byte.)
[**] By the way, I assume that you don't have the Ultra2 or
80 pin versions of the WD9100 drive. (In my experience,
Ultra2 and SCA drives do not have on-board termination
capability.)
[***] I don't recall if you have to enable/disable SCAM
in the Adaptec 2940UW BIOS. I have either BIOS versions
1.32 or 1.34 in my four 2940UW controllers. (I don't have
any WD drives, Right now I have 8 Seagate drives, 8 IBM
drives, and 4 Hitachi drives ...all SCSI...in my home
computers.)
Regards,
Bill
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