Read Attribute - Incorrect Medium Error?

Kevin D Butt kdbutt at us.ibm.com
Mon Apr 25 11:53:07 PDT 2005


* From the T10 Reflector (t10 at t10.org), posted by:
* Kevin D Butt <kdbutt at us.ibm.com>
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Paul, 

Your statement is true if the Medium is mounted and threaded, but there
are implementations where the medium is considered present (i.e. ADC
load state b MPRSNT=1; MTHRD=0) but it is not loaded far enough to read
the MAM (i.e. ADC load state e. --- e.g. in throat of LTO Tape drive but
not mounted - ejected position, or other technologies where MAM data is
stored on medium and not in a CM).  After a load to mounted position the
MAM can be read (or threaded in those technologies where MAM is stored
on medium).  These two scenarios are what I am thinking of. 

Thanks, 
 
Kevin D. Butt
Fibre Channel & SCSI Architect, IBM Tape Firmware, 
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 



Paul.A.Suhler at certance.com 


04/25/2005 11:28 AM 

To
Kevin D Butt/Tucson/IBM at IBMUS 

cc
owner-t10 at t10.org, t10 at t10.org 

Subject
Re: Read Attribute - Incorrect Medium Error?

	






Hi, Kevin.

If the MAM isn't accessible, is it likely ever to be?  I would guess
not,
making the sense key of MEDIUM ERROR correct.  (Do you have a counter
example?)

Instead, I'd like to suggest changing the beginning of the additional
sense
code name to something other than 'LOGICAL UNIT NOT READY."  This is, of
course, ugly because 0410h is in the middle of a bunch of additional
sense
codes that do begin that way.

If we change either the sense key or the numerical value of the ASC/Q,
then
we would break existing implementations.

Thanks,

Paul Suhler
Firmware Engineer
Quantum Corporation
1650 Sunflower Avenue
Costa Mesa, California  92626
(714) 641-2485 (voice)
(714) 966-7328 (fax)



 

                     "Kevin D Butt"

                     <kdbutt at us.ibm.co        To:       t10 at t10.org

                     m>                       cc:

                     Sent by:                 Subject:  Read Attribute -
Incorrect Medium Error?                                      
                     owner-t10 at t10.org

 

 

                     04/25/2005 09:35

                     AM

 

 






All,

In SPC-3r22a, clause 6.14.1 READ ATTRIBUTE command introduction the
following exists:
<<If the medium is present but the medium auxiliary memory is not
accessible, the READ ATTRIBUTE command
shall be terminated with CHECK CONDITION status, with the sense key set
to
MEDIUM ERROR, and the
additional sense code set to LOGICAL UNIT NOT READY, AUXILIARY MEMORY
NOT
ACCESSIBLE.>>

Why is it a MEDIUM ERROR when we have a LOGICAL UNIT NOT READY
condition?
MEDIUM ERRORs are taken by applications to be nasty problems that cause
the
medium to be called  bad.  In this case, it seems that the medium just
needs to be placed in a different position (e.g. Tape is in the drive
but
not yet mounted.  There is no medium error, but the MAM is not
accessible
until the medium is mounted.)

I think this is in error and needs to be changed to a NOT READY sense
key.

What do you all think?

Thanks,

Kevin D. Butt
Fibre Channel & SCSI Architect, IBM Tape Firmware,
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">Paul,</font>
<br>
<br><font size=2 face="sans-serif">Your statement is true if the Medium
is mounted and threaded, but there are implementations where the medium
is considered present (i.e. ADC load state b MPRSNT=1; MTHRD=0) but it
is not loaded far enough to read the MAM (i.e. ADC load state e. --- e.g.
in throat of LTO Tape drive but not mounted - ejected position, or other
technologies where MAM data is stored on medium and not in a CM). &nbsp;After
a load to mounted position the MAM can be read (or threaded in those technologies
where MAM is stored on medium). &nbsp;These two scenarios are what I am
thinking of.</font>
<br>
<br><font size=2 face="sans-serif">Thanks,</font>
<br><font size=2 face="sans-serif">&nbsp;<br>
Kevin D. Butt<br>
Fibre Channel &amp; SCSI Architect, IBM Tape Firmware, <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>
<br>
<br>
<br>
<table width=100%>
<tr valign=top>
<td width=40%><font size=1 face="sans-serif"><b>Paul.A.Suhler at certance.com</b>
</font>
<p><font size=1 face="sans-serif">04/25/2005 11:28 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">Kevin D Butt/Tucson/IBM at IBMUS</font>
<tr>
<td>
<div align=right><font size=1 face="sans-serif">cc</font></div>
<td valign=top><font size=1 face="sans-serif">owner-t10 at t10.org, t10 at t10.org</font>
<tr>
<td>
<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td valign=top><font size=1 face="sans-serif">Re: Read Attribute - Incorrect
Medium Error?</font></table>
<br>
<table>
<tr valign=top>
<td>
<td></table>
<br></table>
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<br>
<br><font size=2><tt><br>
Hi, Kevin.<br>
<br>
If the MAM isn't accessible, is it likely ever to be? &nbsp;I would guess
not,<br>
making the sense key of MEDIUM ERROR correct. &nbsp;(Do you have a counter<br>
example?)<br>
<br>
Instead, I'd like to suggest changing the beginning of the additional sense<br>
code name to something other than 'LOGICAL UNIT NOT READY." &nbsp;This
is, of<br>
course, ugly because 0410h is in the middle of a bunch of additional sense<br>
codes that do begin that way.<br>
<br>
If we change either the sense key or the numerical value of the ASC/Q,
then<br>
we would break existing implementations.<br>
<br>
Thanks,<br>
<br>
Paul Suhler<br>
Firmware Engineer<br>
Quantum Corporation<br>
1650 Sunflower Avenue<br>
Costa Mesa, California &nbsp;92626<br>
(714) 641-2485 (voice)<br>
(714) 966-7328 (fax)<br>
<br>
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All,<br>
<br>
In SPC-3r22a, clause 6.14.1 READ ATTRIBUTE command introduction the<br>
following exists:<br>
<<If the medium is present but the medium auxiliary memory is not<br>
accessible, the READ ATTRIBUTE command<br>
shall be terminated with CHECK CONDITION status, with the sense key set
to<br>
MEDIUM ERROR, and the<br>
additional sense code set to LOGICAL UNIT NOT READY, AUXILIARY MEMORY NOT<br>
ACCESSIBLE.>><br>
<br>
Why is it a MEDIUM ERROR when we have a LOGICAL UNIT NOT READY condition?<br>
MEDIUM ERRORs are taken by applications to be nasty problems that cause
the<br>
medium to be called &nbsp;bad. &nbsp;In this case, it seems that the medium
just<br>
needs to be placed in a different position (e.g. Tape is in the drive but<br>
not yet mounted. &nbsp;There is no medium error, but the MAM is not accessible<br>
until the medium is mounted.)<br>
<br>
I think this is in error and needs to be changed to a NOT READY sense key.<br>
<br>
What do you all think?<br>
<br>
Thanks,<br>
<br>
Kevin D. Butt<br>
Fibre Channel &amp; SCSI Architect, IBM Tape Firmware,<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:<br>
kdbutt at us.ibm.com<br>
<br>
<br>
<br>
<br>
<br>
</tt></font>
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