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Hallam, Ken J Ken.Hallam at unisys.com
Thu Feb 26 15:43:36 PST 1998


* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* "Hallam, Ken J" <Ken.Hallam at unisys.com>
*
With all due respect to Bob Snively, SCSI command implementations that
use the Linked bit in the Control field have been used in our lifetimes,
and continue to be used. Who else but a mainframe supplier of
proprietary systems and software would have a legacy support requirement
for Command Linking? Yes, we do.

However, your model of how the Link bit should work matches fairly well
to our implementation Bob. Although, I do try and discourage this sort
of thing internally, once your designs have a dependency like this, it's
hard to extract yourself. Both drives and host adapters have been
available, (in parallel SCSI) to support it, so there has been no
compelling reason to shift to a new design architecture, (and it's
attendant expense). Now Fibre Channel may be an entirely different
situation. Operating devices through a switch or 2 in a multi-initiator
environment will make Linked command implentation a bit more
problematic.


Ken
Ken Hallam
Unisys 
25725 Jeronimo Road
M/S 201
Mission Viejo, CA 92691
714-380-5115 Voice
714-380-5858 Fax
ken.hallam at unisys.com
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