Log Sense Command

Lohmeyer, John JLOHMEYE at cossymwest.co.symbios.com
Fri Nov 15 10:25:00 PST 1996

* From the SCSI Reflector (scsi at symbios.com), posted by:

Mark Hertz <Mark_Hertz at notes.seagate.com> wrote:
>If a host sends a LOG SENSE command with an allocation length of four   
and the
>target responds by returning four bytes of data for the Log Page header,   
>should the value in the Page Length field (bytes two and three) be?
>   a) the number of bytes available for the specified log page within   
>   b) zero, since no additional data was transferred.

I believe the correct answer is a).  However, with a quick scan through   
SCSI-2, I could not find any place that actually says this for LOG SENSE.   
 I found many other places that say various returned length fields are   
not adjusted to reflect truncation caused by insufficient allocation   
length.  I found no cases where returned length fields are to be adjusted   
for truncation.  So, for consistency with general SCSI-2 conventions, I'd   
vote for not adjusting the page length field.  Certainly, not adjusting   
the page length field is easier for the target and it gives the initiator   
some useful information (how much data is available if the initiator   
wants it).

It would be interesting to find out whether SPC fixes this omission...

John Lohmeyer                 E-Mail: john.lohmeyer at symbios.com
Symbios Logic Inc.             Voice: 719-533-7560
4420 ArrowsWest Dr.              Fax: 719-533-7036
Colo Spgs, CO 80907-3444    SCSI BBS: 719-533-7950 300--14400 baud

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