QErr, Basic Queuing and SBP-2

Charles Monia 237-6757 monia at AM.SHRMSG.SHR.mts.dec.com
Fri Feb 21 05:39:58 PST 1997


* From the SCSI Reflector (scsi at symbios.com), posted by:
* Charles Monia 237-6757 <monia at AM.SHRMSG.SHR.mts.dec.com>
*
Hi:

Just to clear this up, what I said was that the basic queuing model should not
clear **any** commands period. No matter what initiator they came from.  It
should simply do nothing.

Given that behavior, I believe the issue of multi-initiator support is moot.

Charles

| * 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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| *
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| 

************************************************************ ***** *
* Charles Monia, Storage Architecture Group                      *
* Digital Equipment Co.  Internet: charles.monia at shr.mts.dec.com *
* Tel: (508) 841-6757    X400: c=US; a=MCI; o=Digital; ou=SHR    *
* Fax: (508) 841-6100                                            *
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