Tidying up recent changes to the Device Identification Page

Tom Coughlan coughlan at star.zko.dec.com
Tue Dec 16 06:52:24 PST 1997


* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* coughlan at star.zko.dec.com (Tom Coughlan)
*
Two changes approved during the past year or so to the SPC Device 
Identification Page appear to have been slightly incomplete.   These 
problems are evident in the new version of SPC-2 r1.

Problem #1

The note on page 130 of SPC-2 says:

"NOTE 53 In the case of virtual logical units (e.g., volume sets as defined 
by SCC), the Identifier field (see table 111) may be constructed in a 
vendor-specific manner. Vendors should ensure that such identifiers are 
globally unique and have an Identifier type value of 0."

This contradicts document 97-101r2 "IEEE Tutorial for SCSI use of IEEE 
company_id", which says:

"For logical units that are virtual devices (e.g. RAID virtual volumes), it 
is recommended that the FC-PH IEEE Registered Extended name be used."

(The IEEE Registered Extended name has an Identifier type value of 3.)

I recommend that the note be changed to read:

"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 
information."


Problem #2

The paragraph at the top of page 131 of SPC-2 says:

"Each Identification descriptor (see table 111) contains information 
identifying the logical unit. If the logical unit is accessible through any 
other path, it shall return the same identification."

This statement is no longer true, as a result of the "Addition of 
Association field to the Device Identification Page" (96-214r0).  When the 
association field is 1h, then the Identification descriptor applies to the 
port, not the logical unit.

I recommend that the paragraph be moved to immediately after Table 113, 
where the Association field is described, and reworded as follows:

"If a physical or logical device returns an Identification descriptor with 
the Association field set to 0h, it shall return the same descriptor when
it is accessed through any other path."

Tom Coughlan
OpenVMS SCSI Project Leader
Digital Equipment Corporation
110 Spit Brook Rd. ZKO3-4/U14
Nashua, New Hampshire 03062-2698
Telephone: 603-884-0933
Fax.: 	   603-884-0189
Mail: 	   tom.coughlan at digital.com
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