PS_REQ primitives

Greg Tabor greg.tabor at
Tue Mar 1 20:34:14 PST 2011

* From the T10 Reflector (t10 at, posted by:
* Greg Tabor <greg.tabor at>
PS_REQ (PARTIAL) and PS_REQ (SLUMBER) are defined as redundant primitives 
sequences.  The exact rules for redundant primitive sequences are defined in 
SPL, but in short, a redundant primitive sequence consists of the
primitive transmitted 6 times consecutively.  I believe that figure 104 only 
shows a single PS_REQ primitive sequence followed by a single PS_ACK
sequence, each consisting of 6 of the same primitive transmitted 
consecutively.	(Note, of course, that PS_REQ and PS_ACK primitive sequences 
may also include deletable primitives such as ALIGN or NOTIFY between any of 
the "consecutive" primitives).
In general, a single PS_REQ primitive sequence (6x primitives) constitutes a 
request to enter a low phy power condition, and a single PS_ACK primitive 
sequence (6x primitives) constitutes acknowledgement.  Read clause 6 
thoroughly for the complete rules governing low phy power conditions.
Greg Tabor
Maxim Integrated Products
On Tuesday, March 01, 2011 05:02:42 pm Tom Huber wrote:
> In SAS 2.1, is it required that more than one PS_REQ is sent before the
> PS_ACK?  In SAS SPL 2.1 rev 7 figure 104 shows multiple PS_REQs.
> -Tom Huber
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