Question on Read-Write Error Recovery mode page PER operation

Bill.Martin at emulex.com Bill.Martin at emulex.com
Mon Nov 10 09:13:18 PST 2008


Formatted message: <a href="r0811103_f.htm">HTML-formatted message</a>

Kevin:
I meant that my proposed change to the text was consistent with the table
entries.
Bill Martin
Emulex
Office of Technology
Industry Standards
916 772-3658
916 765-6875 (Cell)
bill.martin at emulex.com
________________________________
From: Kevin D Butt [mailto:kdbutt at us.ibm.com]
Sent: Monday, November 10, 2008 8:32 AM
To: Martin, Bill
Cc: Ayalasomayajula, Narayan; owner-t10 at t10.org; t10 at t10.org
Subject: Re: Question on Read-Write Error Recovery mode page PER operation
Bill,
Did you mean to say "This interpretation is consistent..." or did you mean to
say, "This interpretation is INconsistent..."  which is what it seems to me.
If PER is set to one, then you report RECOVERED ERROR on your temporary
errors, but if PER is set to zero, then you do not report anything because
your ERP worked.  That is how IBM tape drives have functioned for decades.
Thanks,
Kevin D. Butt
SCSI & Fibre Channel Architect, Tape Firmware
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-2869 / 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt at us.ibm.com
http://www-03.ibm.com/servers/storage/
From:
Bill.Martin at Emulex.Com
To:
<t10 at t10.org>
Cc:
<Narayan.Ayalasomayajula at Emulex.Com>
Date:
11/07/2008 05:29 PM
Subject:
Question on Read-Write Error Recovery mode page PER operation
________________________________
In the description of PER in the Read-Write Error Recovery mode page, the
following is stated:
A post error (PER) bit set to one specifies that if a recovered read error
occurs during a command performing a read or write operation, then the device
server shall terminate the command with CHECK CONDITION status with the sense
key set to RECOVERED ERROR. A PER bit set to zero specifies that if a
recovered read error occurs during a command performing a read or write
operation, then the device server shall terminate the command with CHECK
CONDITION status, and shall perform error recovery procedures within the
limits established by the error recovery parameters. If the DTE bit is set to
one, then the PER bit shall be set to one.
It seems that the first and second sentences require mostly the same thing as
far as reporting a CHECK CONNDITION.  I think that the second sentence is
missing a "not" in the device server shall NOT terminate the command with
CHECK CONDITION status, ...
This interpretation is consistent with the first two rows of table 128 also,
which state "The device server shall not report recovered read errors. The
device server shall terminate a command performing a read or write operation
with CHECK CONDITION status before the transfer count is exhausted only if an
unrecovered error is detected."
Bill Martin
Emulex
Office of Technology
Industry Standards
916 772-3658
916 765-6875 (Cell)
bill.martin at emulex.com



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