SAS identification of phys in wide ports

Elliott, Robert (Server Storage) Elliott at hp.com
Fri Feb 7 13:28:19 PST 2003


* From the T10 Reflector (t10 at t10.org), posted by:
* "Elliott, Robert (Server Storage)" <Elliott at hp.com>
*
Currently, software has no way to tell exactly which phy in a wide port
is attached to which phy in the attached wide port.  All the phys share
the same pairs of SAS address and Attached SAS address values, but the
last granularity of detail is unavailable.

This information could be communicated with these changes:
* in the IDENTIFY address frame, include the phy identifier of the phy
sending the frame.
* in the SMP DISCOVER function, Protocol-Specific mode page, and
Protocol-Specific log page, return the ATTACHED PHY IDENTIFIER alongside
the ATTACHED SAS ADDRESS.  

Specific locations could be:
* IDENTIFY address frame: byte 27 (current reserved)
* DISCOVER function: byte 39 (currently reserved)
* SAS phy mode descriptor: byte 31
* SAS phy log descriptor: insert 7 reserved bytes after byte 23, and
insert this as new byte 31


This would be hard to add later (e.g. in SAS-2) since phy identifier 0
is a valid identifier.

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



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