SPC-4 Protocol Specific Logical Unit mode page

Mike Berhan mikeb at bustrace.com
Thu Dec 18 06:33:19 PST 2008

* From the T10 Reflector (t10 at t10.org), posted by:
* "Mike Berhan" <mikeb at bustrace.com>
Advanced apologies if this has already been pointed out.
Page 444, Table 359, SPC-4 r17.  This table defines the Protocol Specific
Logical Unit mode page.  Offset 2, bits 7-4 are reserved.  Offset 3+ are the
protocol specific mode parameters.
Page 561, Table 221, SAS-2 r15 (same applies to SAS-1).  This table details
the SAS version of this mode page.  Note, however, that SAS defines bit 4
offset 2 as the "Transport Layer Retries" bit.
Reserved is well defined as:
3.3.8 reserved: A keyword referring to bits, bytes, words, fields and code
values that are set aside for future
standardization. A reserved bit, byte, word or field shall be set to zero,
or in accordance with a future extension to
this standard. Recipients are not required to check reserved bits, bytes,
words or fields for zero values. Receipt of
reserved code values in defined fields shall be reported as an error.
The SAS specification conflicts with the SPC specification in this regard.
I believe SPC-4 should be amended to clarify this conflict.  Perhaps define
that one bit, or all four bits, as protocol specific as opposed to reserved.
Mike Berhan
busTRACE Technologies
9700 Village Center Drive
Suite 50-F
Granite Bay, CA  95746
916.773.4554 phone
916.218.6283 fax
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