Here I get to use the perennial answer to performance questions;  It
depends.

If you intend to use DDS devices simultaneously, you will have to
contend with the Fast SCSI-2 bandwidth limitation for all the devices on
that bus.  The Fast SCSI specifications call for up to 10 MB/second, but
that will only be in your dreams.  On an HP 3000, think closer to 5
MB/second.

I would say that if you place a pair of DDS3 and nothing else on that
bus, you should get proper performance.  You might even add a third one,
but no more.   To be honest, I shy away from DDS technology, so I am
sure someone out there has more hands-on knowledge of the load one can
place on a single bus on an HP3000 with these devices.  It might also
help if you specified which model 3000 you are talking about.


Denys

-----Original Message-----
From: HP-3000 Systems Discussion [mailto:[log in to unmask]]On
Behalf Of Craig Lalley
Sent: Thursday, August 28, 2003 11:35 PM
To: [log in to unmask]
Subject: DDS performance and SCSI stuff ... (Atten: Denys)

Hello list,

In the spirit that the list knows all.

I have a SCSI bus defined as HP28642A, I am not sure what the
performance specs
are.

My question is, how many DDS3 HPC1537A devices (2MB/s) can be put on the
above
SCSI chain before performance will degrade and the DDS3 will not stream
efficiently?

I'm thinking three (3) would be the max and probably be pushing it.

How many 1533 DDS2? or 1504B DDS drive drives can operate efficiently on
the
internal single ended SCSI A2372-60003?

Thanks everyone.

-Craig

 or 1504B

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