My original question posted to alpha-osf-managers on Feb 7, 1996:
> Hi, can anyone give me advice or personal experience on this?
> I have an AlphaServer 1000 4/200 with Digital UNIX 3.0. It has a
> Fast SCSI-2 bus. Can I add older plain (non-fast) SCSI-2 or SCSI-1
> devices (such as older disks or tape drives) to this bus? Will they
> work correctly? Will they slow down the bus for the internal fast
> SCSI-2 disk drives? Thanks for any information.
I received answers from the following. Thank you.
"Anthony D'Atri" <aad_at_nwnet.net>
alan_at_nabeth.cxo.dec.com
David Gadbois <gadbois_at_cyc.com>
atoalu2_at_ato.abb.se (Andreas Lundgren)
"THOMSON, Dave" <THOMSOND_at_WELLINGTON.ECNZ.co.nz>
The responders all agreed that I can mix SCSI-1, SCSI-2, and Fast
SCSI-2 devices on the same Fast SCSI-2 bus. I must adhere to the Fast
SCSI-2 length limitations (3 meters total) and use high quality cables
and terminators.
Some old SCSI-1 devices did not implement the protocol specification
very carefully and could fail on a SCSI-2 bus due to the tighter
tolerances.
The slow speed devices do not drag down the speed of the faster ones,
except by "getting in the way". A SCSI-1 device will take longer to
make a data transfer on the bus. While that is going on, the fast
devices can't use the bus.
One responder cautioned me against mixing SCSI-1 devices with a Fast
SCSI-2 RAID Controller on the same bus.
-Phil Farrell, Computer Systems Manager
Stanford University School of Earth Sciences
farrell_at_pangea.stanford.edu
Received on Thu Feb 08 1996 - 01:19:37 NZDT