SSC-4: ERASE(16) command description flaw?

Ballard, Curtis C (StorageWorks) curtis.ballard at hp.com
Fri Apr 23 10:18:30 PDT 2010


Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r1004232_f.htm">HTML-formatted message</a>

I believe the difference is that the logical position following an ERASE(16)
command with a long bit set to one is always undefined.  The standard doesn't
have any qualifiers about the command having been successful.
When the locate operation fails the logical position is now undefined even
when the long bit is set to zero.
It would also be true to drop that qualifier since the position is undefined
for both values of long following a locate failure.
Curtis Ballard
Hewlett Packard
StorageWorks Platforms Tape
Fort Collins, CO
(970) 898-3013
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Kevin D Butt
Sent: Friday, April 23, 2010 10:39 AM
To: Tim Jones
Cc: owner-t10 at t10.org; t10 at t10.org
Subject: Re: SSC-4: ERASE(16) command description flaw?
Tim,
In the ERASE(16) command, the CDB carries the Partition and LBA of the
location to begin the erase operation.	The medium is to be located to that
position then the erase begin.	If the locate to the initial position fails
that failure occurs before the erase operation has begun.  Hence, the setting
of the LONG bit that is used in the erase operation should have no bearing on
the locate operation.
Thanks,
Kevin D. Butt
SCSI & Fibre Channel Architect, Tape Firmware
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 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:
Tim Jones <tjmac at tolisgroup.com>
To:
t10 at t10.org
Date:
04/23/2010 09:10 AM
Subject:
Re: SSC-4: ERASE(16) command description flaw?
Sent by:
owner-t10 at t10.org
________________________________
* From the T10 Reflector (t10 at t10.org), posted by:
* Tim Jones <tjmac at tolisgroup.com>
*
I believe that the question should be "What happens if a locate operation
fails when the LONG bit **IS** set to 1?"  Is there a difference in the task
that must then be performed to resolve the failure?
Tim
--
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		tjmac at tolisgroup.com
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On Apr 22, 2010, at 6:12 PM, Kevin D Butt wrote:
>
> In reading SSC-4, ERASE(16) command I am confused by the last sentence in
this paragraph:
>
> <<The partition and logical object identifier fields specify the position
at which the ERASE(16) command shall start. If the current position does not
match the specified logical object identifier and partition fields, the
device server shall perform a locate operation to the specified logical
object identifier and partition prior to performing the erase operation. If
the locate operation fails, the device server shall return CHECK CONDITION
status and the additional sense code shall be set to LOCATE OPERATION
FAILURE. The logical position is undefined following a locate operation
failure with a LONG bit of zero.>>
>
> Why does the value of the LONG bit make any difference in whether or not
the position after a failed locate operation is defined?  I think this
sentence is not accurate and should be modified to read, "The logical
position is undefined following a locate operation failure."
>
> Thanks,
>
> Kevin D. Butt
> SCSI & Fibre Channel Architect, Tape Firmware
> MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
> Tel: 520-799-5280
> Fax: 520-799-2723 (T/L:321)
> Email address: kdbutt at us.ibm.com
> http://www-03.ibm.com/servers/storage/
*
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