No subject

Charles Monia monia at am.shrmsg.shr.MTS.dec.com
Thu May 4 14:48:37 PDT 1995


|  "Sense data shall be preserved by the logical unit until it is
|   transferred by one of the methods listed below or until another
|   task from that initiator is entered into the task set.  The
|   information may be obtained by the intiator through:

|   a) The REQUEST SENSE command
|   b) An asynchronous event report
|   c) Autosense delivery"

|I'd like to get a clearer definition of what SAM means (from the
|Target's perspecive) by the term "transferred".  Does this imply
|"successful transfer", or does merely refer to the act of physically
|transmittingt the autosense?  

|If it means successful transfer, then we may have to reevaluate
|whether or not SPI conforms, and whether or not FCP without confirmed
|responses conforms.  If it means just the physical transfer, then
|both FCP and SPI conform to this clause.

It means that the logical unit has entrusted the data to the LLP service for
delivery. This is not to be construed as implying that data has been
succesfully received by some LLP entity in the initiator. That guarantee
depends on the quality of service provided by the LLP.
 
The behavioral model for the service delivery subsystem is described in the
last paragraph of 5.5, which states:

"The request or response package is "sent" when it is passed to the service
delivery port for transmission; it is "in transit" until delivered and
"received" when it has been forwarded to the receiver via the destination
device's service delivery port."
 
In keeping with that model, the word "transferred" in the quoted paragraph
above, should be changed to "sent". (Note that the sender and receiver in this
model are ULP entities.)

Of course, there is no provision in this model for notifying the sender as to
whether or not the ULP recipient has seen the transmitted data. ie. There's no
way to tell from this model whether or not the recipient is brain-dead. (In
some systems, this is tested by having ULP entities periodically poll one
another.)


Charles Monia





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