Alternative to: Proposal for Writable Device Identifiers

Ericson, George gericson at clariion.com
Thu Feb 12 11:22:58 PST 1998


* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* "Ericson, George" <gericson at clariion.com>
*


> -----Original Message-----
> From:	Tom Coughlan [SMTP:coughlan at star.ENET.dec.com]
> Sent:	Thursday, February 12, 1998 11:41 AM
> To:	Ericson, George
> Cc:	t10 at symbios.com; coughlan at star.ENET.dec.com
> Subject:	RE: Alternative to: Proposal for Writable Device
> Identifiers
> 
> >	[GME]  Yes.  So minimally, this would require embedding an SCC
> >device within LUN 0 of a peripheral device.
> 
> That seems far more complex and less likely to be implemented than an
> optional mode page whose format is compatible with the Device ID page.
> 
	[GME]  Remember that each device will have to choose to
implement the new functionality.  Since both solutions are optional,
neither would be ubiquitous.   As a result, your code will have to deal
with devices that don't implement this feature.  On the device, the
added complexity associated with setting the SCCS bit is that two
additional, perhaps unneeded, appendages are dragged along.  In
particular:
*	An error case for unknown LUN_V from the Report Storage Array
Configuration service action of the Volume Set(In) command, and
*	Support for the Report Unconfigured Capacity service action of
the Maintenance (In) command.
	So, I would say there is some added complexity.

	I believe you'll agree it is sub-optimal to create multiple
commands to perform essentially the same function.   As a result, I
suggest working towards a single mechanism.  Two possible actions T10
could take:
*	Adopt your new Mode_Select/Sense pages and obsolete the
get/set_peripheral_device/component_identification pages from the
Maintenance_In/Out commands.
	or,  
> *	Move a subset of the maintenance commands from SCC to SPC and
> make them optional unless the SCCS bit is set in the returned inquiry
> data page, If so, follow the SCC rules for command inclusion.
> 
	Bottom line, either is acceptable to me.  Let's hear what others
have to say.

Regards,
George Ericson

CLARiiON                              A Data General Corporation
Coslin Drive, MS-C44              Tel: 508 480-7349 
Southboro, Ma. 01772             Fax: 508 480-7913
   

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