QErr, Basic Queuing and SBP-2

Jim Mcgrath jmcgrath at QNTM.COM
Thu Feb 20 18:33:23 PST 1997


* From the SCSI Reflector (scsi at symbios.com), posted by:
* jmcgrath at qntm.com (Jim Mcgrath)
*
     
     The problem Peter is what should a Basic queuing device do if put into
     a multiple initiator setting.  According to Charles, it should operate
     proprly (i.e. clear commands for only the affected initiators).  In
     that case, the firmware must be written and tested to support it, and
     so Basic queuing is gutted.
     
     I think you are saying that a Basic queuing device imply should not be
     used in a multiple initiator setting.  I would feel fine with that it
     the Standard said loud clear that a Basic queuing device in a multiple
     initiator setting behaves in a vendor unique manner.  But that is not
     what Charles wants.
     
     I do not want to reject commands from other initiators - I accept them
     today fine, and work well in most applications. I simply do not want
     to handle every corner case - that is what full queuing is all about.

Jim


______________________________ Reply Separator _________________________________
Subject: QErr, Basic Queuing and SBP-2
Author:  PJohansson at aol.com at SMTP
Date:    2/20/97 1:03 PM


* From the SCSI Reflector (scsi at symbios.com), posted by: 
* PJohansson at aol.com
*
....

     
I also think this causes no problem to a single-initiator device, since there 
is only one task set. It seems to me that the diffficulty, if any, is for the 
device to refuse commands from more than one initiator at a time. In SBP-2 
this is not a problem: an initiator must login before it can send commands 
and a single-initiator SBP-2 device accepts only one login at a time. One 
option for a parallel SCSI device would be to return BUSY when a second, 
third, etc. initiator attempted to send a command while a non-empty task set 
existed for another initiator.
     
Regards,
     
Peter Johansson
     
Congruent Software, Inc.
3998 Whittle Avenue
Oakland, CA  94602
     
(510) 531-5472
(510) 531-2942 FAX
     
pjohansson at aol.com
     
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