FW: 00-140r0 - Bug in SAM-2 Task Identifier Definition

Gene_Milligan at notes.seagate.com Gene_Milligan at notes.seagate.com
Fri Mar 24 06:53:14 PST 2000

* From the T10 Reflector (t10 at t10.org), posted by:
* Gene_Milligan at notes.seagate.com

<<"each port is a unique SCSI Device."
The SMU (SCSI Multi-port Unit) concept was created
in an attempt to address that concern.>>

     Not to muddy the water but the above should be ""each port appears to
be a SCSI Device."
The SMU (SCSI Multi-port Unit) concept was created in an attempt to address
that concern."

     My distinction is that, at least for parallel, until all this gets
sorted out there is no such thing as a port - just the SCSI device. I also
take exception to the "unique" since if in deed if the toaster has two of
those no such things there are two SCSI devices sharing a common device

<<As of this writing, the SMU concept is falling into
some disfavor. >>

     I still favor it since the SMU and a vanilla SCSI Device have very
diferent ramifications. I am not necessarily opposed to bringing some of
the additional refinements into the SMU description but I do not want to
see all that baggage lumped under the monichor SCSI Device.

<<In the instance where two
(or more) ports are connected to different busses
or loops, it is perfectly valid for all ports to
end up with the same Target Identifier value.>>

     On the same toaster.

<<First, the Task Identifier object definition
is not symmetric with the Task Address object
definition (which is the identifier an initiator
uses to distinguish one task from another).
Specifically, the Task Address object definition
does not include the Initiator Identifier object.>>

     This does not look like a problem for the initiator since the
initiator does not need to identify itself but would be a problem for the
target that does need to identify the initiator among other initiators.


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