SAS SP state machine extra wait for COMSAS

Elliott, Robert (Server Storage) Elliott at hp.com
Sat Apr 12 15:16:35 PDT 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* "Elliott, Robert (Server Storage)" <Elliott at hp.com>
*
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Due to the conversion from level to edge-based "messages" in the SP
state machine, the SP state machine is now broken in how it handles
COMSAS if that is the first inbound OOB signal it sees.

If SP1:OOB_AwaitCOMX detects COMSAS (rather than COMINIT), it
transitions to SP4:OOB_COMSAS.  SP4:OOB_COMSAS transmits a COMSAS of =
its
own and waits for a COMSAS.  This means the state machine waits for two
COMSASes rather than one.

Really, the state machine knows it saw a COMSAS already; SP4 should
transition directly to SP6:AwaitNoCOMSAS after transmitting its COMSAS.

With our bizarre state machines, I guess the solution is to say the SP1
state passes "COMSAS Detected" with the transition to SP4.  The SP4
state would not wait for a COMSAS if it receives this argument to the
transition.

--=20
Rob Elliott, elliott at hp.com=20
Hewlett-Packard Industry Standard Server Storage Advanced Technology=20
 <https://ecardfile.com/id/RobElliott>
https://ecardfile.com/id/RobElliott=20




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 SAS SP state machine extra wait for COMSAS Due to the conversion from level to = edge-based ;messages; in the SP state machine, the SP state = machine is now broken in how it handles COMSAS if that is the first = inbound OOB signal it sees. If SP1:OOB_AwaitCOMX detects COMSAS = (rather than COMINIT), it transitions to SP4:OOB_COMSAS.  = SP4:OOB_COMSAS transmits a COMSAS of its own and waits for a = COMSAS.  This means the state machine waits for two COMSASes = rather than one. Really, the state machine knows it saw = a COMSAS already; SP4 should transition directly to SP6:AwaitNoCOMSAS = after transmitting its COMSAS. With our bizarre state machines, I = guess the solution is to say the SP1 state passes ;COMSAS = Detected; with the transition to SP4.  The SP4 state would = not wait for a COMSAS if it receives this argument to the = transition. -- 
Rob Elliott, elliott at hp.com 
Hewlett-Packard Industry Standard = Server Storage Advanced Technology 
https://ecardfile.com/id/RobElliott 


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