Target initiated synchronous negotiation

Rick Roche, 508-770-6351 roche at
Thu Jun 1 10:37:03 PDT 1995

>Rick Roche wrote...
>>>  We are revisiting the initiate negotiation question on our disk
>>>  products and we wanted to query the reflector audience for their
>>>  input.
>>>  Currently, we DO NOT initiate synchronous negotiation since some
>>>  early host adapters didn't respond very well to the behavior.  One
>>>  concern with this behavior is an adapter which doesn't re-negotiate on
>>>  check conditions status may result in a sync host with and Async target.
>>>  We do allow for target initiated negotiations to be enabled through
>>>  a mode page control bit, but it's defaulted off.
>>>  One proposal is to turn initiate on for wide negotiations based on
>>>  the argument that most (all?) wide adapters must be more advanced
>>>  and probably handle target initiated negotiations fine.  Is this
>>>  a reasonable assumption?  Do people know of drives which do initiate
>>>  negotiations by default?
>>>  Comments?
>>   IBM high end disk drives can either use or block target initiated
>>synchronous negotiation.  The control is via an option block pin, and
>>can be sensed via a vendor unique mode page flag.  Whatever the customer
>>wants, he gets.


    As mentioned in the second paragraph of my note, we also allow the
    customer to get whatever they want.

    I'm trying to understand if it's safe to change our default behavior
    without causing problems for ANY of our customer however big or small.


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