Subject: Arbitration question
Date: Fri, 3 Oct 2008 10:54:48 -0700
From: "Marian Lakov" <Marian_Lakov@us.xyratex.com>
To: <t10@t10.org>
X-Message-Number: 9169
Formatted message: HTML-formatted message

Hi,
I'm trying to figure out the arbitration priority and where the source
SAS address will be used instead of AWT.
As per SAS spec the only situation where the AWT will be ignored is in:
7.12.4.1 Expander phy arbitration requirements
An expander phy shall set its Request Path request Retry Priority Status
argument to IGNORE AWT when it requests a path after:
a) it has forwarded an OPEN address frame to the physical link;
b) an OPEN address frame is received with higher arbitration priority
(see 7.12.3); and
c) the destination SAS address and connection rate of the received OPEN
address frame are not equal to the source SAS address and connection
rate of the transmitted OPEN address frame (see 7.15.4 and 7.15.9).
Does it mean that if both received and transmitted OPEN address frames
have the same connection rate (i.e. 3Gbps) and the destination SAS
address of the received OPEN address frame is not equal to the source
SAS address of the transmitted OPEN address frame then the AWT will be
ignored and the higher source SAS address will win the arbitration?
Thanks,
Marian
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