Mode Parameter changes and when they take effect

Penokie, George George.Penokie at lsi.com
Wed Aug 6 15:06:29 PDT 2008


Formatted message: <A HREF="r0808067_f.htm">HTML-formatted message</A>

Kevin,
Not specifically, but there is nothing that states modifying user data shall
not or should not cause a POR either but would not be a good implemtation
either. ;-)
Bye for now,
George Penokie
LSI Corporation
3033 41st St. NW
Suite 100
Rochester, MN 55901
507-328-9017
george.penokie at lsi.com
________________________________
From: Kevin D Butt [mailto:kdbutt at us.ibm.com]
Sent: Wednesday, August 06, 2008 4:04 PM
To: Penokie, George
Cc: t10 at t10.org
Subject: RE: Mode Parameter changes and when they take effect
George,
Thanks.  Is there anything anywhere that states that modifying a mode
parameter shall not or should not cause a POR?
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/
"Penokie, George" <George.Penokie at lsi.com>
08/06/2008 01:54 PM
To
Kevin D Butt/Tucson/IBM at IBMUS, "t10 at t10.org" <t10 at t10.org>
cc
Subject
RE: Mode Parameter changes and when they take effect
Kevin,
There are some ways that an action requested in a command may be deferred.
Those are:
1) when the command supports the IMMED bit (MODE SENSE and MODE SELECT do
not)
2) if the command has explicit rules defined as to when a specific action is
to take place ( Mode parameter block descriptor in the mode page parameters
is an example of that)
3) if a specific page has explicit rules defined as to when a specific value
is to take affect. (I know of none but I did not do an extensive search)
If the mode parameters you are referring to in your note do not have explicit
rules stating that are not required to take effect until a POR occurs then
SAM requires them to be valid on completion of the MODE SELECT command. In
other words there is nothing special about the MODE SELECT command that
allows an implementation to treat mode pages any different that any other
kind of parameter data.
Bye for now,
George Penokie
LSI Corporation
3033 41st St. NW
Suite 100
Rochester, MN 55901
507-328-9017
george.penokie at lsi.com
________________________________
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Kevin D Butt
Sent: Wednesday, August 06, 2008 2:09 PM
To: t10 at t10.org
Subject: Mode Parameter changes and when they take effect
I have a question related to Mode Parameters.  I have searched SPC-4 (and
earlier SPC versions) and cannot find guidance about when the changes to mode
parameters take effect.  This concern is related to configuration settings
and differences in expectations of various vendors.
Vendor 1 claims that any change to a mode parameter shall become effective
immediately and should not cause a device to reboot.
Vendor 2 claims that changes to some mode parameters require a reboot before
they can be accomplished.  As such the device automatically performs a POR on
completion of the Mode Select that changes one or more of these parameters.
Vendor 3 also claims that changes to some mode parameters require a reboot
before they can be accomplished.  This device,however, requires that an
outside entity send a command to force the device to perform a POR.  The new
values of the mode parameters are not in effect until after the POR.
In another form of when do parameters take effect, the requested change to
the format (or density) does not occur until a subsequent command (e.g., a
Format, a Write from BOT, etc.).
Is there any guidance in SPC?
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/



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