A/B Port bit in Inquiry Data

ROWEBER at acm.org ROWEBER at acm.org
Sun Feb 1 17:14:08 PST 1998

* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* ROWEBER at acm.org

Several of the drafts of SPC identified bit 5 in byte 6 and the MultiP
bit.  Its function was as you describe, 0=A-port 1=B-port.  The bit has
since been marked vendor-specific, so that implementations that used
the MultiP bit are still good.

Although I cannot speak for the T10 committee, my understanding is that
the desire is to allow implementations with more than two ports.  Hence,
a single bit is insufficient to identify which port, and thus the fate
of the MultiP bit.  Since there is no agreement on the proper upper
limit for the number of ports, no field has been defined in the 
Inquiry data to take the place of MultiP.

All in all, you may wish to consider using the vendor-specific bit
at bit position 5 in byte 6 to implement the port identifier flag
described in your mail.


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