98-115r0 - Sundry Minor Enhancements for SPC-2

Tom Coughlan coughlan at star.zko.dec.com
Wed Feb 11 06:14:05 PST 1998

* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* coughlan at star.zko.dec.com (Tom Coughlan)
At the risk of making a closet-monster out of a dust bunny...

>Topic 4) concerns Note 53 and its suggestion for SCC virtual devices.  
>Contrary to the comments received, the IEEE Tutorial has as one of its many 
>topics, specific, detailed requirements for how SCC virtual devices should 
>develop the unique IDs returned in the Device Identification VPD page.  The
>ideas presented in the IEEE Tutorial conflict substantially with the vendor-
>specific assignment described by Note 53.
>Please note that topic 4) suggests the removal of Note 53, an idea
>generally held as goodness by several in the working group.  Topic 4)
>does not propose adding any text in place of the removed note.  Anyone
>making IEEE unique IDs should be reading the tutorial and no specific
>reference was thought necessary by whomever left this dust bunny in
>the SPC-2 closet.

Not true.  My reflector message on 16-DEC-1997 did propose a reference to
the tutorial.  I believe that part of the reason the tutorial was created
was to make SCSI implementors aware of the fact that they may need to
generate IEEE unique IDs above-and-beyond what is provided by the
underlying transport.  For this reason, there should be a reference to the
tutorial somewhere in the SCSI documents. 

My original suggestion was:

"NOTE 53 In the case of virtual logical units (e.g., volume sets as defined 
by SCC), the Identifier field (see table 111) should be an IEEE Registered 
Extended name.  The IEEE Registered Extended name shall have an Identifier 
type value of 3h, and an NAA value of 0110b, as defined in FC-PH.  Refer to 
"IEEE Tutorial for SCSI use of IEEE company_id" (97-101r2) for more 

If it is impossible for SPC to refer to 97-101r2, and if the editor is
unable to obtain a suitable reference to the IEEE tutorial, then I would
settle for removal of the last sentence.  I think the remainder of the note
should stay for two reasons:  first, to make amends for the incorrect
guidance that was provided by previous versions of SPC on this topic, and 
second, to provide guidance to implementors on an issue that is critical to
achieving interoperability of storage devices.

I think Gene hinted that this information belongs in SCC, not SPC.  I would
agree, except for the fact that the note providing misleading guidance has
already appeared in SPC.  I think we should update it and leave it in SPC
to help folks recover.

Tom Coughlan
OpenVMS SCSI Project Leader
Digital Equipment Corporation
Nashua, New Hampshire
tom.coughlan at digital.com
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