Kevin,

See my comments below.

Mark,

There appears to be a small bug in the power condition state machine. In the case were:

a) The idle condition timer is active;

b) The idle condition timer is zero.

c) The standby condition timer is active; and

d) The standby condition timer is zero.

There is no description of which transition should be used from the PC1:Active.state. I realize that in the end, if the PC1:Active to PC2:Idle transitions is taken there will be a transition from PC2:Idle to PC3:Standby right away which would have the same effect as a PC1:Active to PC3: Standby but it would be clearer to the reader if a single clear active was defined for this case.

Bye for now,
George Penokie

LSI Corporation
3033 41st St. NW
Suite 100
Rochester, MN 55901

507-328-9017
george.penokie@lsi.com

From: owner-t10@t10.org [mailto:owner-t10@t10.org] On Behalf Of Kevin D Butt
Sent: Monday, August 25, 2008 10:58 AM
To: t10@t10.org
Cc: Hirokazu Nakayama
Subject: Power Condition Mode Select interpretation of intent

I have a question of the intent of the Power Condition mode parameters.

The following text is from SPC-4r16.
<<
7.4.12 Power Condition mode page

The Power Condition mode page provides an application client with methods to control the power condition of a
logical unit (see 5.10). These methods include:
a) Specifying that the logical unit transition to a power condition without delay; and
b) Activating and setting of idle condition and standby condition timers to specify that the logical unit wait for a period of inactivity before transitioning to a specified power condition.
>>
Item a) implies to me that there is a method of telling the target to "go to specified power condition immediately (i.e., now)".
Item b) implies to me that there is a method of specifying a timer value for when to transition to the power condition.

Is the intent of listing a) separately to infer that a timer value of zero is the "go immediately" command and that it is a one time event? (GP - No, although this could be subject to interpretation. If you look in the power conditions state machine you will see it is not a one time change. When the power condition is active (i.e., the bit is set) and the timer is zero the transitions occur.) Or is the intent that the timer value is modified to be zero and the side effect of that modification is that the power condition is immediately transitioned to? (GP - No) Stated differently, does a mode select specifying a power condition timer of zero modify that timer until the next mode select (or event that changes mode parameters) thereby causing a device to transition out of and back into that state on the receipt and completion of each command that causes a transition (e.g., write) (GP - Yes, the power transitions would occur any time there is no active command.) ?

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@us.ibm.com
http://www-03.ibm.com/servers/storage/