LUN instantiation question

Peter Johansson PJohansson at
Tue Mar 5 09:03:49 PST 2002

* From the T10 Reflector (t10 at, posted by:
* Peter Johansson <PJohansson at>
At 06:07 AM 3/5/2002 -0600, Ralph Weber wrote:

>See 5.8.5 (Unit Attention condition):
>... "In addition, a logical unit shall generate a unit attention condition 
>for each initiator whenever one of the following events occurs:
>f) The logical unit inventory has been changed;

Ralph, what is the history of this requirement? It seems to first appear in 
SAM-2 Revision 11, July 16, 1999.

I have in mind a model where LUs are created at the behest of some client 
application with no intention that they be accessible to anyone save the 
creator. It would be of no use to notify other initiators that a new LU exists.

So, some questions:

1) What is the "logical unit inventory"? Is it only the LUNs reported in 
response to REPORT LUNS? SPC-3 definition 3.1.41 seems to say this. If so, 
are LUNs that exist but are not reported by REPORT LUNS exempt from the 
unit attention requirements of 5.8.5?

2) Could 5.8.5 be revised to provide exemption from the mandatory unit 
attention condition when a LU appears or disappears? I understand the 
importance of this behavior for some applications, but also think it's 
possible to describe a use model where such reporting is unimportant---even 
a burden.


Peter Johansson

Congruent Software, Inc.
98 Colorado Avenue
Berkeley, CA  94707

(510) 527-3926
(510) 527-3856 FAX

PJohansson at

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