Question on Scope: 8-byte vs 2-byte LUNs

George M. Ericson ericson at worldnet.att.net
Wed Apr 8 16:14:16 PDT 1998


* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* "George M. Ericson" <ericson at worldnet.att.net>
*
Ralph, IBM George,

I would not use level as a criteria.

SPC-2 REPORT LUNS says:
	The REPORT LUNS command shall return information
	about only those logical units to which commands may be sent.

If a device aggregates some number of LUs into another LU, then the device
must make a policy decision.  Either it will continue to allow the contained
LUs to be accessed independently to the containing LU, or not.

In particular, we could add words to SCC to say that aggregation of LUs into
Redundancy Groups encapulates them within the Redundancy Group and they are
therefore no longer directly accessible. This would have the desired effect
of making them invisible to REPORT LUNS.

BTW, the last posting of IBM George would allow the use of REPORT LUNS.
It's just that the REPORT LUNS would have to return the 8xxx class LUNs.

Regards,
CLARiiON George

-----Original Message-----
From: owner-t10 at Symbios.COM [mailto:owner-t10 at Symbios.COM]On Behalf Of
George Penokie
Sent: Wednesday, April 08, 1998 3:51 PM
To: t10 at Symbios.COM
Subject: Re: Question on Scope: 8-byte vs 2-byte LUNs


* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* George Penokie <gop at us.ibm.com>
*
I think this bounced so I am sending in again.

Ralph,
I assume asking the IBM George not the DG George this question, although I
think the DG George may have also have an opinion on this. Yes I agree it
makes
sense to limit REPORT LUNs to the first level. But I am not sure how to put
that in the standards. I think the best we could do would be to put a
recommendation in the REPORT LUNs command that application clients only
issue
it to target:LUN=0 devices. This would prevent it from being issued to
devices
in the lower levels.
Bye for now,
George


owner-t10 at Symbios.COM on 04/07/98 08:26:21 AM
Please respond to owner-t10 at Symbios.COM
To: T10 at Symbios.COM
cc:
Subject: Re: Question on Scope: 8-byte vs 2-byte LUNs


* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* ROWEBER at acm.org
*
George,

You've hit on the main point I would have brought up, if I'd been able
to type faster.  The output from the REPORT LUNS command cannot be used
as input to the applicable SCC commands that configure virutal units.

Now that you've worked through all of that, my only remaining issue
concerns recommendations for how application clients should use the
REPORT LUNS command.  When an application client sends a REPORT LUNS
command to a level other than the one it can address directly, the
application client runs the risk of "seeing" levels of the hierarchy
it cannot address.  My preference would be to suggest that the REPORT
LUNS command never be passed through to lower levels and/or that
application clients never sent REPORT LUNS commands to lower levels.

Since we now know that the REPORT PERIPHERAL DEVICE service action
must be used for configuration purposes, there should be no need to
pass the REPORT LUNS command to lower levels.

What do you think?

Ralph...
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