Disabled SAS Expander Port

Elliott, Robert (Server Storage) elliott at hp.com
Mon Dec 8 14:57:53 PST 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* "Elliott, Robert (Server Storage)" <elliott at hp.com>
*
> * From the T10 Reflector (t10 at t10.org), posted by:
> * Gil Romo <gil.romo at qlogic.com>
> *
> 
> Would a SAS device ever attempt to open a connection through 
> a disabled port along the path to another SAS device?

Sure.  It might not have been the one that disabled the
previously working phy(s), so might not know not to make a
request through them any more.

Assume the environment is:
device A ------- phy 0  expander  phy 1 ------- device B

> If the originator-side expander port could not receive the 
> OPEN address frame, the originator would timeout.

If expander phy 0 is disabled, the link goes down and device
A encounters a the loss of dword sync directly.

> If the responder-side expander port could not forward the 
> OPEN address frame, it might be forwarded out the
> expander's "subtractive" port, resulting in an 
> OPEN_REJECT (WRONG DESTINATION) response.
>
> Is this the expected behavior?

If phy 0 is part of the subtractive port, it results in
OPEN_REJECT (NO DESTINATION).  See 7.12.5.2 "If the
destination phy is in the same expander port as the source
phy and the source phys are using the subtractive routing 
method, the edge expander device shall reply with 
OPEN_REJECT (NO DESTINATION)."

> What would be the expander's response if it did not 
> include a "subtractive" port.

This also gets OPEN_REJECT (NO DESTINATION). See 7.12.5.2
"If it does not find a match and no subtractive routing
phy is available, the edge expander device shall reply
with OPEN_REJECT (NO DESTINATION)."

> Thanks.
> ------------
> Gilbert Romo
> Circuits & Integration
> QLogic Corporation, Aliso Viejo, California
> Office: 949-389-6266
> E-mail: gil.romo at qlogic.com


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


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