Implementation details for LVD/Single Ended mode changes

I think the word you're looking for is 'Space Ranger' ppagels at tdh.qntm.com
Thu Sep 25 10:05:14 PDT 1997


* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* ppagels at tdh.qntm.com (I think the word you're looking for is 'Space Ranger')
*



    Quantum is looking at fine tuning our firmware implementation of
    LVD/Single Ended mode changes, just related to the logical stuff, like
    handling outstanding commands.  Here's the behavior we're proposing.

    o Clear the queues
    o Go back to asynch/narrow
    o Clear contingent allengiance, ECA, and reservations
    o We're debating whether to re-initialize mode pages
    o We're debating whether to restart SCAM
    o Report check condition status on the next I/O from all hosts, with a
      subsequent sense data of 06/29/05 for LVD to SE changes and 06/29/06
      for SE to LVD changes.


    Our questions are...

    1. Are host adapter implementors planning on asserting SCSI RST when
       they detect a bus mode change?  If so, will it be after the 100 mS
       delay?

    2. What kind of sense data would the host adapter implementors like to
       see reported by a the target after a bus mode change?

    3. Bus mode changes are not supported when the bus is active in SPI-2. But
       if we detect that we are currently connected for a command after the
       2 mS timer for a  bus mode change.  We are planning on forcing an
       unexpected bus free.  Any thoughts on this issue.

    4. One option for handling bus mode changes previously discussed on the
       reflector was treating it like a SCSI bus reset.  We're not sure all
       the activities required per SCSI-2 for the hard reset alternative 
       should be executed on a bus mode change.  The ones we're thinking 
       should not be executed include re-initializing mode pages and
       re-starting SCAM.  The grayer ones are things like clearing out
       contingent allengiance and reservations.  What would host adapter
       implementors like to see here?

    Thanks,

    Patty

--------------------------------------------------------------------------------

    Patty Pagels                            Phone (508) 770 5690
    Quantum Corporation                     FAX   (508) 770 2604
    reply to: pagels at leds.enet.qntm.com

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