Interaction between untagged task and simple task?

Kevin D Butt kdbutt at us.ibm.com
Fri Jul 25 15:04:52 PDT 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* Kevin D Butt <kdbutt at us.ibm.com>
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What is the interaction between untagged and simple tasks from the same
initiator supposed to be? 
As an example: 
write (untagged) 
inq (simple) 
write (untagged) 

I have searched the standards (SAM-2) and did not find any reference to
the interaction between an untagged task and a simple tagged task.   

In describing an untagged task clause 4.9.1 states: 
An untagged task is represented by an I_T_L nexus (see 4.10) and is
composed of a definition of the work to be performed by the logical
unit, and implicitly a SIMPLE task attribute (see 7.5). 
 and 
An untagged task does not include a tag in its I_T_L nexus, thus
restricting the number of concurrent untagged tasks in a single task set
to one per initiator. Also, an untagged task is assumed to have a SIMPLE
task attribute, leaving the initiator no control over its relationship
to other tasks in the task set.

I can guess that a simple tagged task can be processed after an untagged
task begins but that an untagged task received after a simple tagged
task begins and before it completes must get an overlapped command check
condition.  However, I am just guessing that this is wha the behavior
should be. 

Can anybody enlighten me? 

Thanks, 

Kevin D. Butt
Fibre Channel & SCSI Architect, IBM Tape Microcode, 
6TYA, 9000 S. Rita Rd., Tucson, AZ  85744
Tie-line 321; Office: 520-799-5280, Lab: 799-5751, Fax: 799-4138, Email:
kdbutt at us.ibm.com

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<br><font size=2 face="sans-serif">What is the interaction between untagged and simple tasks from the same initiator supposed to be?</font>
<br><font size=2 face="sans-serif">As an example:</font>
<br><font size=2 face="sans-serif">write (untagged)</font>
<br><font size=2 face="sans-serif">inq (simple)</font>
<br><font size=2 face="sans-serif">write (untagged)</font>
<br>
<br><font size=2><tt>I have searched the standards (SAM-2) and did not find any reference to the interaction between an untagged task and a simple tagged task. &nbsp;</tt></font>
<br>
<br><font size=2><tt>In describing an untagged task clause 4.9.1 states:</tt></font>
<br><font size=2><tt>An untagged task is represented by an I_T_L nexus (see 4.10) and is composed of a definition of the work to be performed by the logical unit, and implicitly a SIMPLE task attribute (see 7.5).</tt></font>
<br><font size=2><tt>&nbsp;and</tt></font>
<br><font size=2><tt>An untagged task does not include a tag in its I_T_L nexus, thus restricting the number of concurrent untagged tasks in a single task set to one per initiator. Also, an untagged task is assumed to have a SIMPLE task attribute, leaving the initiator no control over its relationship to other tasks in the task set.</tt></font><font size=2 face="sans-serif"><br>
</font>
<br><font size=2 face="sans-serif">I can guess that a simple tagged task can be processed after an untagged task begins but that an untagged task received after a simple tagged task begins and before it completes must get an overlapped command check condition. &nbsp;However, I am just guessing that this is wha the behavior should be.</font>
<br>
<br><font size=2 face="sans-serif">Can anybody enlighten me?</font>
<br>
<br><font size=2 face="sans-serif">Thanks,</font>
<br><font size=2 face="sans-serif"><br>
Kevin D. Butt<br>
Fibre Channel &amp; SCSI Architect, IBM Tape Microcode, <br>
6TYA, 9000 S. Rita Rd., Tucson, AZ &nbsp;85744<br>
Tie-line 321; Office: 520-799-5280, Lab: 799-5751, Fax: 799-4138, Email: kdbutt at us.ibm.com</font>
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