Conflict with exception handling selection mode page

Mark Hertz Mark_Hertz at notes.seagate.com
Tue Dec 5 12:59:13 PST 1995


George Penokie said:
>In true SCSI fashion we have created an unresolvable inconsistancy between the
>definations of the interval timer field and the report count field in the
>exception handling selection mode page.
>
>The current defination for the zero value of the interval timer states 'the
>target shall only report the informational exception condition one time.'
>While the defination for the zero value of the report count field states
>'there is no limit on the number of times the target shall report an
>informational exceptin condition.'
>
>So the question is; How many times is the informational exception condition
>reported if both the interval timer and the report count fields are set to
>zero?
>
>The answer according to SCSI; Don't make both fields zero !!!!!
>
>That answer is, of course, no good.  I would like to propose the defination
>of the interval timer field be changed to: 'A value of zero on the interval
>timer field shall indicate the timer interval is vendor specific.' and that
>the FFFFFFFFh value being defined as vendor specific be dropped.

I would rather see the definition for the Interval Timer field be modified to 
the following: 

A value of zero in the INTERVAL TIMER field indicates that the target shall 
only report the informational exception condition one time regardless of the 
value in the REPORT COUNT field.  A value of FFFFFFFFh in the INTERVAL TIMER 
field shall indicate the timer interval is vendor specific.  If the Method of 
Reporting Informational Exceptions (MRIE) field is method six then the INTERVAL 
TIMER field is ignored.

Here's my logic to the above definition, if the Interval Timer field is zero 
then a target can't initialize internal timers for the next report period and 
if the next report time can't be established then a target can only report 
once.  As for the removal of the statement "A value of FFFFFFFFh in the 
INTERVAL TIMER field shall indicate the timer interval is vendor specific.",  I 
don't care if that statement is dropped.  Our device's consider a value of 
FFFFFFFFh as a very large number and simply round the field down to a vendor 
specific (maximum) value.

Now consider the last statement in my definition.  If reporting method six is 
selected (i.e., "Only report information exception condition on request") then 
clearly the host establishes it own reporting interval by issuing unsolicited 
REQUEST SENSE commands.  So the INTERVAL TIMER field becomes redundant, however 
the REPORT COUNT field is still valid.




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