REPORT LUNS and SCC devices

Ron Gould ron at
Thu Jun 20 21:59:04 PDT 1996

* From the SCSI Reflector, posted by:
* Ron Gould <ron at>
An old discussion but some more questions.

>* From the SCSI Reflector, posted by:
>* "George Penokie" <GOP at RCHVMP3.VNET.IBM.COM>
>Ron writes,
>> As an initiator we have a need to determine the known logical units
>> in an SCC device.  If a REPORT LUNS command is sent to an SCC device
>> what should it return?  Could the SCC device report the LUNs associated
>> with all of the addressing methods (volume set, peripheral device, logical
>> unit, base address)?
>The answer is Yes.  When a REPORT LUNs command is sent to the base address
>(LUN 0) of a SCC device the SCC should report all directly addressable
>LUNs it knows about.(Volume sets, and peripheral devices; note those are
>the only two types of objects that can be directly addressed.)

Can any of the addressable LUNs reported overlap?  In other words, if 
there are some devices in the array that have been configured into a 
volume can the REPORT LUNs report back both the periheral devices and 
volume set associated with this storage?  If so, how does the initiator 
(host) determine that this is the case?

How does one address a peripheral device?  The logical unit and addressing 
and peripheral device addressing methods seem to accomplish the same thing 
of providing a way to do bus/target/LUN addressing.  What is the real 
difference in these two addressing methods and when should each be used?  

>Also, don't confuse addressing methods (which are part of the LUN) with
>the LUN.  Addressing method is a field within the 8 byte LUN structure.
>If you have any questions about this let me know.
>Bye for now,
>George Penokie

Ron Gould
ron at

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