99-179r1 -- commands that must be serviced in foreground mode

Neil T. Wanamaker ntw at crossroads.com
Fri Jun 4 12:09:12 PDT 1999

* From the T10 Reflector (t10 at symbios.com), posted by:
* "Neil T. Wanamaker" <ntw at crossroads.com>
At 02:28 PM 6/4/99 -0400, Bill Dallas wrote:
>* From the T10 Reflector (t10 at symbios.com), posted by:

>The OS environments and SCSI are moving to a dynamic topology model.  To
>track changes in the topology, the tools that SCSI provides to uniquely
>ID a device are the inquiry VPD pages (pages 80 or 83).  The devices that
>reject these commands while in self test can not be id'ed in a single system
>or Cluster environment.  
>Start/Stop commands are used in conjunction with Inquiry commands (VPD) since
>some devices do not return VPD information unless spun up.  While I consider
>a device that can't return VPD information for page 80 or 83 to be seriously
>flawed it is something I have to live with due to history.
>What would really be nice is a new command like inquiry that returns
>a device's unique id no matter what, just like inquiry.  This would allow
>the restriction of Start/Start and VPD info but would allow the OS to track
>the topology while a device is in self-test.

While this seems close, I would think that what you want is the media-id -
the OS normally cares much less about the devices than the data sets.
Antique OSs used to label the media for this purpose. Unfortunately, it is
much harder to design a drive so that the media-id is available during the
self-test...this shouldn't be too hard on a fixed drive, and media changers
can read the cartridge-id while the unit is being self-tested (but the OS
needs to understand the relationship between the changers & devices). 

| Neil T. Wanamaker         Crossroads Systems, Inc.              |
| ntw at crossroads.com        			  		                      	 |    
| (512)794-2727                                                   |
| (512)349-0304 FAX    Web URL - http://www.crossroads.com        |
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