Resend: Availability of Logical Unit Reset document

snively at scsi snively at scsi
Thu Sep 28 10:42:38 PDT 1995


Resend for possible mailer failure.  Sorry for any duplicates

The document has been transmitted to the SCSI ftp site and I expect that
it will be transferred to the public directories this week.  Here 
is the paragraph describing the change, together with text extracted
|from the document showing the suggested wording for the definition of
hierarchical addressing.


Cover letter change description:

Revision 3 adds the definition of hierarchical logical units for 
SAM-2 and provides the value for the SIP message. This noticeably 
simplifies some of the other explanations.


New text provided for SAM or SAM-2:



The definition of a SCSI target having hierarchical addressing must be 
provided. A likely section to do this would be in section 4.7.4 immediately 
after Object definition 6 (Logical Unit). The text would be included as 
a paragraph immediately following the last line of the Object Descriptions, 
Logical Unit Identifier.


"A logical unit is said to be uniquely addressed if there is no interaction 
or relationship between that logical unit and any other logical unit in 
the same target."

"A logical unit is said to be hierarchically addressed if an identical 
value of some number of the high order bits of the logical unit number 
imply a hierarchical relationship among the logical units having that 
value. The base logical unit number of a hierarchical addressing structure 
is that logical unit number having a particular value of high order bits 
and having all the lower order bits equal to 0. Dependent logical unit 
numbers are those having the same high order bits as the base logical 
unit number, but nonzero low-order bits. The logical unit having the 
base logical unit number has the properties of logical unit 0 with respect 
to all other hierarchically addressed logical units having dependent 
logical unit numbers. The base logical unit always exists in a set of 
hierarchically addressed logical units and provides a well known address 
for performing configuration management, status and type verification, and 
the LOGICAL UNIT RESET task management function for the logical units 
having dependent logical unit numbers."



The object address for the LOGICAL UNIT RESET contains the logical unit 
number of a destination logical unit. The logical unit and all dependent 
logical units, if any, will be reset. SAM-2 would be the same as 
SAM revision 18, but modified in the following manner.


Section 6 should have the following text added between the descriptions of 
CLEAR TASK SET and TARGET RESET.

"LOGICAL UNIT RESET (Logical Unit Identifier||) - Reset the specified 
logical unit and terminate all tasks in all task sets. For SCSI targets 
having unique addressing, implementation of this function is a logical 
unit option. All hierarchically addressed SCSI devices shall support 
this function. Resetting of a base logical unit shall reset all 
dependent logical units and terminate their task sets."





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