Comments on 09-250r2: SPC-4 Change power condition timer behavior when commands are received

Gerry.Houlder at Gerry.Houlder at
Wed Sep 30 11:21:22 PDT 2009

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A concern that came out at the last meeting is that the command
descriptions should not describe any interaction with timers. That
interaction should be in only one place, namely the model clause that is
earlier in the proposal. We don't want to have descriptions that might
conflict with each other.
However, there does need to be something added to the REQUEST SENSE command
so it is clear that the device server shall be capable of completing the
command while in a low power condition. So far this is the only command
with that "shall" requirement.
How about replacing the existing text in REQUEST SENSE with this:
"The device server shall be capable of completing a REQUEST SENSE command
while the logical unit is in a low power condition."
This wording would more clearly relate the required REQUEST SENSE behavior
with the timer interaction described in the model clause. I realize that
this would be a change from the existing REQUEST SENSE wording, but we need
to standardize the behavior to conform to the model we picked at the last
CAP meeting.
	     Kevin D Butt					       
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				       Comments on 09-250r2: SPC-4 Change
				       power condition timer behavior when
	     09/29/2009 02:09	       commands are received	       
In 09-250r2 under the REQUEST SENSE command I think that the changes are a
little more than what you have.
Before the changes made earlier in the proposal, the timers were stopped
for the processing of the Request Sense command and then restarted.  Also,
the previous text implies that the power condition may have changed for
processing the command.  After the changes in this proposal, the Request
Sense command is processed in parallel with any power condition timers that
are running and the state upon the completion of the Request Sense command
is not necessarily the same power condition state as when the command was
enabled.  Rather, the power condition state transitions are not effected by
the REQUEST SENSE command and a state transition may have occurred during
the processing of the command.
I suggest the following wording to replace the paragraph listed in the
Processing a REQUEST SENSE command shall not have an effect on the power
condition of the logical unit. A REQUEST SENSE command shall not reset any
power condition timers.
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

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