Date:  Nov 25,1993                        X3T9.2/93-191 rev 0


   To:  X3T9.2 Committee (SCSI)

   From:  George Penokie (IBM)

   Subject:  SDA States and Types

   1.0 Overview

   The SCSI-3 Disk Array Model requires the definition of several
   new SCSI device types.  This proposal lists all the new SCSI
   devices types that are required for the SCSI-3 Disk Array
   Model.

   The SCSI-3 Disk Array Model also needs to define the state of
   SCSI devices.  The state of a device is an indication of its
   current operating condition.  The state information gives an
   application client the information required for to do
   configuration services to a SDA.

   2.0 SCSI-3 Device Types

   This proposal requests the following peripheral device
   types be added to the SCSI-3 peripheral device type table:

  +========-====================================================+
  |  Code  | Description                                        |
  |--------+----------------------------------------------------+
  |   0Ch  | SCSI disk array device                             |
  |   0Dh  | Power supply device                                |
  |   0Eh  | Operation panel device                             |
  |   0Fh  | LED device                                         |
  |10h-19h | Vendor Specific                                    |
  +=============================================================+

   These changes would become part of the peripheral device type
   table in the SCC standard.  The new peripheral device type
   table would appear as follows:

                          Table xx - Peripheral device type
  +========-====================================================+
  |  Code  | Description                                        |
  |--------+----------------------------------------------------+
  |   00h  | Direct-access device (e.g. magnetic disk)          |
  |   01h  | Sequential-access device (e.g. magnetic tape)      |
  |   02h  | Printer device                                     |
  |   03h  | Processor device                                   |
  |   04h  | Write-once device (e.g. some optical disks)        |
  |   05h  | CD-ROM device                                      |
  |   06h  | Scanner device                                     |
  |   07h  | Optical memory device (e.g. some optical disks)    |
  |   08h  | Medium changer device (e.g. jukeboxes)             |
  |   09h  | Communications device                              |
  |0Ah-0Bh | Defined by ASC IT8 (Graphic arts pre-press devices)|
 ||   0Ch  | SCSI disk array device                             |
 ||   0Dh  | Power supply device                                |
 ||   0Eh  | Operation panel device                             |
 ||   0Fh  | LED device                                         |
 ||10h-19h | Vendor Specific                                    |
 ||1Ah-1Eh | Reserved                                           |
  |   1Fh  | Unknown or no device type                          |
  +=============================================================+

   3.0 SCSI-3 Disk Array States

   The following is a list of states that shall be returned as
   part of the parameter list returned in SDA service requests.

   Not Available - The selected logical unit is capable of being
   supported but no device is connected.

   Broken - The selected logical unit is capable of being
   supported but it has failed.

   Readying - The selected logical unit is being initialized and
   access to the logical unit is limited.

   Active - The selected logical unit is fully operational.

   Rebuild - The selected logical unit is in the process of a
   rebuild operation.

   Recalculate - The selected logical unit is in the process of a
   recalculate operation.

   Error - Within the selected logical unit a part that does not
   effect performance has failed.  In this state all data is
   still fully protected (e.g.  power supply failure, LED
   failure, etc.).

   Degraded Performance - Within the selected logical unit a part
   that effects performance has failed.  In this state all data
   is still fully protected (e.g.  cache failure, etc.)

   Exposed - Within the selected logical unit data is not
   protected.  In this state all data is still valid.

   Note:  This is a normal state if the logical unit is within a
   redundancy group that has a redundancy type of no redundancy.

   Implememtors Note: A logical unit that has a redundancy type of
   on redundancy should report a state of active rather than
   exposed during normal operations.

   Partial - Within the selected logical unit data has been lost.

   <<Editors note:I do not think this table has any value and would
   like to remove it.  Any comments? - GOP>>

                   P-extent  P-LUI  Redundancy  Volume Set  Spare
                                      Group

   Not Available      Y        Y          N         N         N
   Broken             Y        Y          N         N         Y
   Readying           Y        Y          Y         Y         Y
   Active             Y        Y          Y         Y         Y
   Rebuild            Y        Y          Y         Y         Y
   Recalculate        Y        Y          Y         Y         Y
   Error              Y        Y          Y         Y         Y
   Degraded Perf.     Y        Y          Y         Y         Y
   Exposed            N        N          Y         Y         N
   Partial            N        N          Y         Y         N