Interface power management telecon later today

Elliott, Robert (Server Storage) Elliott at
Wed May 28 09:33:42 PDT 2008

* From the T10 Reflector (t10 at, posted by:
* "Elliott, Robert (Server Storage)" <Elliott at>
I cannot make the call, but some feedback:
1. Do we really need two states (Partial and Slumber)?	Maybe Partial would
suffice. Is the SATA market really using both of them?
2. Entry should be by a new Interface Power Management address frame, not a
The address frame should be acknowledged with an AF_ACK as proposed in
07-119; an AF_NAK should be added as well, if a "understood but temporarily
rejected" response is needed.
SATA's PMNAK doesn't differentiate between "will never accept" and
"temporarily not accepting - that problem should be avoided.
We should not introduce repeated primitives like PMACK and PMNAK into SAS
(EMI issues).
An address frame:
- clearly limits usage to outside connections
- should mesh better with OPEN address frame handling
- can carry more information. Examples:
  - which state is requested (Partial, Slumber, etc.)
  - the requested recovery time
  - a power consumption limit
  - the estimated time the phy thinks it will be idle
  - how aggressively to wake up a phy in a wide link
  - other future ideas
- is CRC protected (not 3-of-6 detected like redundant primitives)
3. The IDENTIFY address frame and/or SNW-3 needs bits/fields reporting
whether IPM is supported.  If the attached phy does not support it, don't
request it.
4. I'm not sure ALIGN (0) after COMWAKE is the best pattern for 6 Gbps phys. 
They currently align on TRAIN and TRAIN_DONE patterns now, which has lower
frequency content in the primitive and more spectrally rich content in the
data dwords.  ALIGN (0) may stress EMI more than the TRAIN/TRAIN_DONE
5. The Energy Efficient Ethernet proposals involve periodically waking up and
sending some bits, so the receiver PLL drift can be limited and recovery time
shortened.  With spread spectrum clocking, this may be hopeless for SAS.
Rob Elliott, HP Industry Standard Server Storage
-----Original Message-----
From: owner-t10 at [mailto:owner-t10 at] On Behalf Of
Gerry.Houlder at
Sent: Wednesday, May 28, 2008 8:57 AM
To: t10 at
Subject: Interface power management telecon later today
* From the T10 Reflector (t10 at, posted by:
* Gerry.Houlder at
This is a reminder of the Interface Power Management telecon scheduled for
2:00 to 4:00 PM CDT today.
In addition to the agenda items described below, recently posted proposal
08-249 will also be discussed as time permits.
----- Forwarded by Gerry Houlder/Seagate on 05/28/2008 08:52 AM -----
	     Gerry.Houlder at sea
	     Sent by:							To
	     owner-t10 at	       t10 at
	     (952) 402-2869						cc
	     05/20/2008 04:55	       Interface power management telecon
	     PM 		       announcement
* From the T10 Reflector (t10 at, posted by:
* Gerry.Houlder at
There will be an Interface Power Managment telecon on
May 28 at 2:00 PM CDT.
This telecon will specifically discuss proposals 08-015r2 and 08-206r0,
both of which are posted on T10 web site.
The telecon will specifically discuss:
(a) try to agree on the PHY states that need to be added,
(b) identify communications that may be needed with other state machines,
(c) timing requirements for getting into and out of low power states,
(d) application layer controls to allow/ disallow power management.
phone information:
USA:  877-873-8019
participant: 8314923#
webex information:
Topic: gerry.houlder's meeting
Date: Wednesday, May 28, 2008
Time: 2:00 pm, Central Daylight Time (GMT -05:00, Chicago )
Meeting Number: 820 660 429
Meeting Password: partial
Please click the link below to see more information, or to join the
To join the online meeting
1. Go to
2. Enter your name and email address.
3. Enter the meeting password: partial
4. Click "Join".
* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at
* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at
* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at

More information about the T10 mailing list