Prioritized Unit Attention Reporting

peterson_gary at emc.com peterson_gary at emc.com
Thu Feb 10 13:50:11 PST 2005


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To:       T10

 

From:   Gary S. Peterson

            EMC Corporation, CLARiiON Division

 

Re:       Prioritized Unit Attention Reporting

 

Date:    February 10, 2005

 

            In the ongoing development of our storage systems, we have
come to the conclusion that reporting multiple Unit Attentions on an
I_T_L nexus basis is desirable to report the various conditions to the
initiators communicating with our array may encounter. However, our
design does not easily lend itself to open-ended queuing of Unit
Attention conditions due to the large number of I_T_L nexus that we
support in our storage arrays. 

 

            We are instead considering a "prioritized" Unit Attention
structure. Each potential Unit Attention report will be assigned a
priority level for reporting, with each level holding a single Unit
Attention condition. The highest priority Unit Attention condition will
be reported on the next command from the affected initiator. The second
highest priority Unit Attention condition will be reported on the second
command received from the affected initiator, and so on.

 

            The priority structure we're currently looking at that is
along the following lines:

            

            Priority 1 (Highest): Logical Unit Existence (as seen by the
initiator) Changed

                        06/3F/0E          REPORT LUNS DATA Has Changed

                        

            Priority 2: Logical Unit Capacity Changed

                        06/3F/0A         VOLUME SET CREATED OR MODIFIED

 

            Priority 3: Logical Unit Access Changed

                        06/2A/04         RESERVATIONS RELEASED

                        06/2A/05         RESERVATIONS PREEEMPTED

 

            Priority 4: Logical Unit Task Set Changed

                        06/2F/00          COMMANDS CLEARED BY ANOTHER
INITIATOR

            

            Priority 5 (Lowest): Logical Unit Parameters Changed

06/29/00          POWER ON, RESET OR BUS DEVICE RESET OCCURRED

                        06/2A/01         MODE PARAMETERS CHANGED

 

 

A reading of the ANSI documentation regarding multiple Unit Attention
conditions only states that "Logical Unit may queue Unit Attention
conditions." (SAM-2, section 5.9.5).

 

 

We therefore have two questions:

 

1.      Is our proposed reporting scheme legal from an ANSI standards
viewpoint?

2.      Is this (or a similar) scheme something ANSI wishes to add to
the standards?

 

 


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<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>To:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
T10<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>From:&nbsp;&nbsp; Gary S. Peterson<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; EMC Corporation, CLARiiON Division<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>Re:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Prioritized Unit =
Attention Reporting<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>Date:&nbsp;&nbsp;&nbsp; February 10, =
2005<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; In the ongoing development of our storage systems, we have
come to the conclusion that reporting multiple Unit Attentions on an =
I_T_L
nexus basis is desirable to report the various conditions to the =
initiators communicating
with our array may encounter. However, our design does not easily lend =
itself
to open-ended queuing of Unit Attention conditions due to the large =
number of
I_T_L nexus that we support in our storage arrays. =
<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; We are instead considering a "prioritized" Unit
Attention structure. Each potential Unit Attention report will be =
assigned a
priority level for reporting, with each level holding a single Unit =
Attention
condition. The highest priority Unit Attention condition will be =
reported on
the next command from the affected initiator. The second highest =
priority Unit
Attention condition will be reported on the second command received =
|from the
affected initiator, and so on.<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; The priority structure we're currently looking at
that is along the following lines:<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; <o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; <u>Priority 1 (Highest): Logical Unit Existence (as seen by
the initiator) Changed<o:p></o:p></u></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; 06/3F/0E&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <span =
style=3D'text-transform:
uppercase'>REPORT LUNS DATA Has =
Changed</span><o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; <o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; <u>Priority 2: Logical Unit Capacity =
Changed<o:p></o:p></u></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; 06/3F/0A&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; VOLUME SET =
CREATED OR MODIFIED<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; <u>Priority 3: Logical Unit Access =
Changed<o:p></o:p></u></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; 06/2A/04&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
RESERVATIONS RELEASED<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; 06/2A/05&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
RESERVATIONS PREEEMPTED<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; <u>Priority 4: Logical Unit Task Set =
Changed<o:p></o:p></u></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
06/2F/00&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; COMMANDS =
CLEARED BY ANOTHER
INITIATOR<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; <o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; <u>Priority 5 (Lowest): Logical Unit Parameters =
Changed<o:p></o:p></u></span></font></p>

<p class=3DMsoNormal =
style=3D'margin-left:2.0in;text-indent:-1.0in'><font size=3D3
face=3D"Times New Roman"><span =
style=3D'font-size:12.0pt'>06/29/00&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&=
nbsp;&nbsp;&nbsp; POWER
ON, RESET OR BUS DEVICE RESET OCCURRED<o:p></o:p></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs=
p; 06/2A/01&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; MODE =
PARAMETERS CHANGED<span
style=3D'text-transform:uppercase'><o:p></o:p></span></span></font></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal style=3D'text-indent:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'>A reading of the ANSI documentation =
regarding multiple
Unit Attention conditions only states that "Logical Unit may queue Unit
Attention conditions." (SAM-2, section =
5.9.5).<o:p></o:p></span></font></p>

<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'>We therefore have two =
questions:<o:p></o:p></span></font></p>

<p class=3DMsoNormal style=3D'margin-left:.5in'><font size=3D3 =
face=3D"Times New Roman"><span
style=3D'font-size:12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal =
style=3D'mso-margin-top-alt:6.0pt;margin-right:0in;margin-bottom:
0in;margin-left:.75in;margin-bottom:.0001pt;text-indent:-.25in;mso-list:=
l0 level1 lfo1'><![if !supportLists]><font
size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:12.0pt'><span
style=3D'mso-list:Ignore'>1.<font size=3D1 face=3D"Times New =
Roman"><span
style=3D'font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
</span></font></span></span></font><![endif]>Is
our proposed reporting scheme legal from an ANSI standards =
viewpoint?<o:p></o:p></p>

<p class=3DMsoNormal =
style=3D'mso-margin-top-alt:6.0pt;margin-right:0in;margin-bottom:
0in;margin-left:.75in;margin-bottom:.0001pt;text-indent:-.25in;mso-list:=
l0 level1 lfo1'><![if !supportLists]><font
size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:12.0pt'><span
style=3D'mso-list:Ignore'>2.<font size=3D1 face=3D"Times New =
Roman"><span
style=3D'font:7.0pt "Times New Roman"'>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
</span></font></span></span></font><![endif]>Is
this (or a similar) scheme something ANSI wishes to add to the =
standards?<o:p></o:p></p>

<p class=3DMsoNormal><font size=3D3 face=3D"Times New Roman"><span =
style=3D'font-size:
12.0pt'><o:p>&nbsp;</o:p></span></font></p>

<p class=3DMsoNormal><font size=3D2 face=3DArial><span =
style=3D'font-size:10.0pt;
font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>

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