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A500 Model A5570B SCSI terminators?

 
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Paul Francis
Occasional Visitor

A500 Model A5570B SCSI terminators?

I have some A500 boxes to look after but they have no SCSI terminators. There are no external SCSI devices attached to the SCSI connectors.

My question is: should the A500 have SCSI terminators attached, and if so can someone provide the part numbers?

Thank You.
5 REPLIES 5
Jeff Schussele
Honored Contributor

Re: A500 Model A5570B SCSI terminators?

Hi,

No - generally not.
When the card itself is the end of the SCSI bus, then it provides it's own termination internally.
BUT when devices are chanied off it, then THEY need to supply termination either through their own internal capability are frequently with the external terminators.
But when in doubt - ask HP.

Rgds,
Jeff
PERSEVERANCE -- Remember, whatever does not kill you only makes you stronger!
Joshua Scott
Honored Contributor

Re: A500 Model A5570B SCSI terminators?

Jeff is correct, the A500 doesn't need terminators.

If there were external devices connected, then the terminator part number depends on the connection at the end of the SCSI bus.
What are the chances...
Paul Francis
Occasional Visitor

Re: A500 Model A5570B SCSI terminators?

Thanks for the replies.

However, all the HP docs that I have seen indicate that the SCSI connectors should be terminated. I am told that when HP shipped these boxes (and others of the same type) that there were terminators present. I don't have these now, so that's the problem.

Jeff Schussele
Honored Contributor
Solution

Re: A500 Model A5570B SCSI terminators?

Hi Paul,

That may have been true years ago when HBAs weren't supplying active termination internally. But now almost *all* do.

See the following from the rp2400 (A400/500) HW guide:

http://docs.hp.com/hpux/onlinedocs/2411/rp24xx_customer.pdf

Connect External Small Computer System Interface (SCSI) Devices
Connect external SCSI devices to the Single Ended SCSI bus (labeled: Narrow Single-Ended SCSI Path:
0/0/2/0) on the system card or to the Ultra 2 SCSI bus (labeled: Ultra 2 SCSI Path: 0/0/1/0).
Ensure that all devices on the SCSI bus have a unique address and the last device is terminated. Refer to the
documentation accompanying each device to learn how to set addresses and where to place terminators.

Note that they do *not* state that the HBA itself has to be terminated.
And I checked several A500s out in my data centers & *none* have their uncabled HBAs terminated externally. And they were all installed ny trained HP personnel.

But you believe what you wish...

Later,
Jeff
PERSEVERANCE -- Remember, whatever does not kill you only makes you stronger!
Paul Francis
Occasional Visitor

Re: A500 Model A5570B SCSI terminators?

Thanks very much. The HP doc does say that. That's good enough for me.

The whole issue was very confusing though. Other people with A500s with no external devices say terminate both, or terminate one or terminate none. As long as it is documented then I'm happy.

Thanks again,

Paul Francis