RE: Receiving a SCSI response after abort task was sent

With one minor warning, I agree with David.
 
Warning below:

________________________________

From: [email protected] [mailto:[email protected]] 
Sent: Monday, July 03, 2006 6:54 AM
To: [email protected]; [email protected]
Subject: RE: [Ips] Receiving a SCSI response after abort task was sent


Erez,
 
> I have a question about aborting tasks: when an initiator sends "abort
task" to the target,
> it is possible that the target will send a SCSI response for the same
task before receiving the
> abort task (I guess that the target won't send a task management
response for the abort task).
 
Yes and (No) in that order.  The "abort task" task management function
is defined to succeed when the task does not exist - the response will
indicate success in this situation.
 
> What should the initiator do with the SCSI response?
 
Process it normally, as it would any other SCSI Response.
 
> Is the host that issued the abort task willing to receive a SCSI
response for that task?
> Is it willing to receive only a task management response for the abort
task?
 
Yes and No in that order, the SCSI response is possible and must be
handled.  There will always be a task management response, independent
of whether the SCSI response is issued.  One important rule is that
the SCSI response cannot occur *after* the task management response. 
 
In some technologies and under some conditions, it is hypothetically
possible for a SCSI
response to appear at an initiator after the task management response.
In such environments, this will
be detected as a SCSI response for which there is no SCSI request and it
will be discarded. 
Since TCP/IP forces in-order behavior on the SCSI stream, and since the
abort task is
normally sent through the same stream as the command, this normally may
be ignored
by iSCSI.
 
Thanks,
--David
---------------------------------------------------- 
David L. Black, Senior Technologist 
EMC Corporation, 176 South St., Hopkinton, MA  01748 
+1 (508) 293-7953             FAX: +1 (508) 293-7786 
[email protected]        Mobile: +1 (978) 394-7754 
---------------------------------------------------- 


________________________________

	From: Erez Zilber [mailto:[email protected]] 
	Sent: Sunday, July 02, 2006 6:48 AM
	To: [email protected]
	Subject: [Ips] Receiving a SCSI response after abort task was
sent
	
	
	Hi,
	
	I have a question about aborting tasks: when an initiator sends
"abort task" to the target, it is possible that the target will send a
SCSI response for the same task before receiving the abort task (I guess
that the target won't send a task management response for the abort
task). What should the initiator do with the SCSI response? Is the host
that issued the abort task willing to receive a SCSI response for that
task? Is it willing to receive only a task management response for the
abort task?
	
	This message was also sent to linux-scsi mailing list.
	
	Thanks
	
	-- 
	

	____________________________________________________________

	Erez Zilber   |  972-9-971-7689

	Software Engineer, Storage Team

	Voltaire - The Grid Backbone

	

	 www.voltaire.com <http://www.voltaire.com/>

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