[BULK] - SAS Backoff Retry Priority
greg at vitesse.com
Thu Aug 5 20:15:33 PDT 2004
* From the T10 Reflector (t10 at t10.org), posted by:
* Greg Tabor <greg at vitesse.com>
Is your concern that the Retry Priority Status rule contradicts the
statement in 7.12.5:
"After an expander device transmits an AIP, it shall not transmit an
OPEN address frame unless it has higher arbitration priority than the
incoming connection request."
If so, here are two points to consider:
1. In 126.96.36.199 the definition of "arbitration priority" is changed when
IGNORE_AWT is set.
2. If, in your example, expander 2 phy Y transmitted an OPEN frame after
AIP with a lower arbwait time than the one it received crossing on the
same link, then the expander to the right of expander 2 would also wind
up backing off and retrying the OPEN it originally forwarded to exp 2.Y
and set IGNORE_AWT when it rearbitrates as well. So, the decision
settles into a consistent state in both expanders.
// Greg Tabor - Vitesse Semiconductor Corporation //
// voice: (719) 867-4414 fax: (719) 867-6203 //
// email: greg at vitesse.com //
Gil Romo wrote:
> An expander obeying backoff retry priority could violate rules stated in
> subclause 7.12.5 "Expander rules and connection requests".
> The attached document describes a scenario where this may occur.
> Gilbert Romo
> Circuits & Integration
> QLogic Corporation, Aliso Viejo, California
> Office: 949-389-6266
> E-mail: gil.romo at qlogic.com
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