Wide or Narrow?

George Penokie gop at us.ibm.com
Thu Aug 26 12:43:27 PDT 2004


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

The sequence you list (i.e., WDTR - PPR - SDTR) is not a legal sequence.
The correct sequence should be (i.e., WDTR - PPR - WDTR - SDTR). These
rules are stated in SPI-5 as: 

4.12.6 Message restrictions 
.... 
WDTR and SDTR may be originated by either SCSI target ports or SCSI
initiator ports. Since WDTR resets all the values that SDTR sets (see
4.12.4.1), it shall be sent first if both are needed. 

SCSI target ports capable of wide transfer agreements shall originate
negotiation with WDTR followed with SDTR. 

However, that said, Table 2 in section 4.12.4.1 (Negotiable fields
introduction) states that the TRANSFER WIDTH EXPONENT is to remain
unchanged during an SDTR requires the bus to remain in the state set in
the PPR message which in your example is wide. 

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





SSchmitz at attotech.com 
Sent by: owner-t10 at t10.org 


08/26/2004 11:49 AM 

To
t10 at t10.org 

cc

Subject
Wide or Narrow?

	





* From the T10 Reflector (t10 at t10.org), posted by:
* SSchmitz at attotech.com
*

Consider three SCSI commands preceeded by the following negotiation:

1.  Async Narrow using the WDTR message (message bytes: 01 02 03 00).
2.  Sync DT 160 using the PPR message (message bytes: 01 06 04 09 00 3E
01
02).
3.  Sync ST 80 using the SDTR message (message bytes: 01 03 01 0A 1F).

At this point, is the bus wide or narrow?  In other words, should
separate
states be maintained for PPR vs. WDTR/SDTR negotiation implying that the
bus is narrow or should one state be maintained implying that the bus is
wide?

-Scott Schmitz


*
* For T10 Reflector information, send a message with
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<br><font size=2 face="sans-serif">Scott,</font>
<br>
<br><font size=2 face="sans-serif">The sequence you list (i.e., WDTR -
PPR - SDTR) is not a legal sequence. The correct sequence should be (i.e.,
WDTR - PPR - WDTR - SDTR). These rules are stated in SPI-5 as:</font>
<br>
<br><font size=2 face="sans-serif">4.12.6 Message restrictions</font>
<br><font size=2 face="sans-serif">....</font>
<br><font size=2 face="sans-serif">WDTR and SDTR may be originated by either
SCSI target ports or SCSI initiator ports. Since WDTR resets all the values
that SDTR sets (see 4.12.4.1), it shall be sent first if both are needed.</font>
<br>
<br><font size=2 face="sans-serif">SCSI target ports capable of wide transfer
agreements shall originate negotiation with WDTR followed with SDTR.</font>
<br>
<br><font size=2 face="sans-serif">However, that said, Table 2 in section
4.12.4.1 (Negotiable fields introduction) states that the TRANSFER WIDTH
EXPONENT is to remain unchanged during an SDTR requires the bus to remain
in the state set in the PPR message which in your example is wide.</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>SSchmitz at attotech.com</b>
</font>
<br><font size=1 face="sans-serif">Sent by: owner-t10 at t10.org</font>
<p><font size=1 face="sans-serif">08/26/2004 11:49 AM</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">t10 at t10.org</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">Wide or Narrow?</font></table>
<br>
<table>
<tr valign=top>
<td>
<td></table>
<br></table>
<br>
<br>
<br><font size=2><tt>* From the T10 Reflector (t10 at t10.org), posted by:<br>
* SSchmitz at attotech.com<br>
*<br>
<br>
Consider three SCSI commands preceeded by the following negotiation:<br>
<br>
1. &nbsp;Async Narrow using the WDTR message (message bytes: 01 02 03 00).<br>
2. &nbsp;Sync DT 160 using the PPR message (message bytes: 01 06 04 09
00 3E 01<br>
02).<br>
3. &nbsp;Sync ST 80 using the SDTR message (message bytes: 01 03 01 0A
1F).<br>
<br>
At this point, is the bus wide or narrow? &nbsp;In other words, should
separate<br>
states be maintained for PPR vs. WDTR/SDTR negotiation implying that the<br>
bus is narrow or should one state be maintained implying that the bus is<br>
wide?<br>
<br>
-Scott Schmitz<br>
<br>
<br>
*<br>
* For T10 Reflector information, send a message with<br>
* 'info t10' (no quotes) in the message body to majordomo at t10.org<br>
</tt></font>
<br>
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