SAS 1.1 Protocol-Specific Logical Unit mode page question

George Penokie gop at us.ibm.com
Thu Aug 4 07:51:31 PDT 2005


* From the T10 Reflector (t10 at t10.org), posted by:
* George Penokie <gop at us.ibm.com>
*
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Bill, 

All mode page bits and fields may or may not be changeable and there is
no way that an initiator can force the target to allow a mode page bit
or field to be changeable or not changeable. That's the architecture of
mode pages in SCSI. 

There are generally two reasons a target makes a mode page bit or field
unchangeable: 

-The has only implemented one of the options available. If this is the
case then, even if the a different value was selected it would do no
good as the target would still work the implemented way. 

-A customer has requested the target manufacturer to only allow a
specific set of options be used. The results is that the customers
options are set and the fields and bits marked unchangeable. 

Bye for now,
George Penokie

Dept 2C6  114-2 N212
E-Mail:    gop at us.ibm.com
Internal:  553-5208
External: 507-253-5208   FAX: 507-253-2880





"Bill Martin" <bill_martin at sierralogic.com> 
Sent by: owner-t10 at t10.org 


08/03/2005 10:01 PM 

To
"Robert Elliot" <elliott at hp.com>, <t10 at t10.org> 

cc

Subject
SAS 1.1 Protocol-Specific Logical Unit mode page question

	





In Protocol-Specific Logical Unit mode page for SAS SSP, there is a
field called "Transport Layer Retries".  There is no indication of a
requirement for this field to be changeable.  While it is possible to
determine if it is changeable in a particular implementation, If it is
not changeable there is no mechanism documented to allow an initiator to
stop the target from performing transport layer retries. 
  
Was the intention that this field be required to be changeable? 
  
  
Bill Martin
Sr. Principal Engineer
Standards and Interoperability
Sierra Logic, Inc.
916 772-3658 
916 765-6875 (Cell)
bill_martin at sierralogic.com 
  


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<br><font size=2 face="sans-serif">Bill,</font>
<br>
<br><font size=2 face="sans-serif">All mode page bits and fields may or
may not be changeable and there is no way that an initiator can force the
target to allow a mode page bit or field to be changeable or not changeable.
That's the architecture of mode pages in SCSI. </font>
<br>
<br><font size=2 face="sans-serif">There are generally two reasons a target
makes a mode page bit or field unchangeable:</font>
<br>
<br><font size=2 face="sans-serif">-The has only implemented one of the
options available. If this is the case then, even if the a different value
was selected it would do no good as the target would still work the implemented
way.</font>
<br>
<br><font size=2 face="sans-serif">-A customer has requested the target
manufacturer to only allow a specific set of options be used. The results
is that the customers options are set and the fields and bits marked unchangeable.</font>
<br><font size=2 face="sans-serif"><br>
Bye for now,<br>
George Penokie<br>
<br>
Dept 2C6 &nbsp;114-2 N212<br>
E-Mail: &nbsp; &nbsp;gop at us.ibm.com<br>
Internal: &nbsp;553-5208<br>
External: 507-253-5208 &nbsp; FAX: 507-253-2880<br>
<br>
</font>
<br>
<br>
<br>
<table width=100%>
<tr valign=top>
<td width=40%><font size=1 face="sans-serif"><b>"Bill Martin"
<bill_martin at sierralogic.com&gt;</b> </font>
<br><font size=1 face="sans-serif">Sent by: owner-t10 at t10.org</font>
<p><font size=1 face="sans-serif">08/03/2005 10:01 PM</font>
<td width=59%>
<table width=100%>
<tr>
<td>
<div align=right><font size=1 face="sans-serif">To</font></div>
<td valign=top><font size=1 face="sans-serif">"Robert Elliot"
<elliott at hp.com&gt;, <t10 at t10.org&gt;</font>
<tr>
<td>
<div align=right><font size=1 face="sans-serif">cc</font></div>
<td valign=top>
<tr>
<td>
<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td valign=top><font size=1 face="sans-serif">SAS 1.1 Protocol-Specific
Logical Unit mode page question</font></table>
<br>
<table>
<tr valign=top>
<td>
<td></table>
<br></table>
<br>
<br>
<br><font size=2 face="Courier New">In Protocol-Specific Logical Unit mode
page for SAS SSP, there is a field called "Transport Layer Retries".
&nbsp;There is no indication of a requirement for this field to be changeable.
&nbsp;While it is possible to determine if it is changeable in a particular
implementation, If it is not changeable there is no mechanism documented
to allow an initiator to stop the target from performing transport layer
retries.</font>
<br><font size=2 face="Courier New">&nbsp;</font>
<br><font size=2 face="Courier New">Was the intention that this field be
required to be changeable?</font>
<br><font size=2 face="Arial">&nbsp;</font>
<br><font size=2 face="Arial">&nbsp;</font>
<br><font size=2 face="Arial">Bill Martin<br>
Sr. Principal Engineer<br>
Standards and Interoperability<br>
Sierra Logic, Inc.<br>
916 772-3658</font>
<br><font size=2 face="Arial">916 765-6875 (Cell)<br>
bill_martin at sierralogic.com</font>
<br><font size=3 face="Times New Roman">&nbsp;</font>
<br>
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