SDA States and Type (94-041r3)

George Penokie GOP at rchvmp3.vnet.ibm.com
Fri Apr 8 08:48:56 PDT 1994


   Date:  Mar 16,1994                        X3T10/94-041 rev 3


   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
   type be added to the SCSI-3 peripheral device type table:

  +========-====================================================+
  |  Code  | Description                                        |
  |--------+----------------------------------------------------+
  |   0Ch  | SCSI disk array device                             |
  +=============================================================+

   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:

.pa
                          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-1Eh | Reserved                                           |
  |   1Fh  | Unknown or no device type                          |
  +=============================================================+

   3.0 Reporting of SCSI-3 Disk Array States

   The reasons for reporting states depend on the which logical
   unit is being addressed.  The following sections describe the
   possible states for each of the addressable components within
   an SCSI Disk Array.

   3.1 SCSI Disk Array States (LUN 0)

   The state of the SDA may be determined by using the same
   methods as any other SCSI device(e.g.  TUR followed by Request
   Sense).  However, more detailed state information may be
 | obtained by issuing a state request to the base device address
   of the SDA.

 | All valid base device address states shall be reported within
   a single state request by setting the appropriate bit(s).  If
   all the bits within the state information field are set to
   zero then the SDA is available.

 | The base device address of an SDA may report any of the
   following states under the listed conditions:

   Readying Bit - The selected SDA is being initialized and
   access to the SDA is limited.

   Available - The selected SDA is operational.

   Present Bit - The selected SDA is present but no other status
   is available.

   Component Failure Bit - Within the selected SDA a
   non-addressable part has failed.  In this state all data is
   still fully protected (e.g.  power supply failure, LED
 | failure, cache failure, etc. that are not defined as C-LUIs).
   More information on the failure may be available within the
 | sense data from a Request Sense Command issued to base device
 | address of the SDA.

   Abnormal Bit - Within the selected SDA an addressable device
 | (C-LUI, P-LUI, R-LUI, V-LUI, or S-LUI) is indicating a state
   other than available.  To determine which device is indicating
   it is not available issue a state request to each addressable
   device within the SDA.

   3.2 Volume Set States

 | Only a single volume set state shall be reported within a
 | single state request.

   Volumes set may report any of the following states under the
   listed conditions:

   Not Available - The selected V-LUI is capable of being
   supported but has not been configured.

   Readying - The selected V-LUI is being initialized and access
   to the V-LUI is limited.

   Available - The selected V-LUI is fully operational.

   Rebuild - One or more of the redundancy groups associated with
   the selected V-LUI is in the process of a rebuild operation.
   In this state data is not protected.

   Protected Rebuild - One or more of the redundancy groups
   associated with the selected V-LUI is in the process of a
   rebuild operation.  In this state all data is fully protected.

   Recalculate - The selected V-LUI is in the process of a
   recalculate operation.

   Spare in Use - Within the selected V-LUI a spare is
   being used. In this state all data is still fully protected.

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

   Data Lost - Within the selected V-LUI data has been lost.

   Broken - The selected V-LUI is capable of being supported but
   it has failed.

   3.3 Redundancy Group States

 | Only a single redundancy group state shall be reported
 | within a single state request.

   Redundancy groups may report any of the following states
   under the listed conditions:

   Not Available - The selected redundancy group is capable of being
   supported but has not been configured.

   Available - The selected redundancy group is fully configured.

   Present - The selected redundancy group is present but no other
   status is available.

   Rebuild - The selected redundancy group is in the process of a
   rebuild operation. In this state data is not protected.

   Protected Rebuild - The selected redundancy group is in the
   process of a rebuild operation.  In this state all data is
   fully protected.

   Recalculate - The selected redundancy group is in the process of a
   recalculate operation.

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

   3.4 P-LUI/P-extent States

   The state of the P-LUI may be determined by using the same
   methods as any other SCSI device(e.g.  TUR followed by Request
   Sense).  However, more detailed state information may be
   obtained by issuing a state request to the P-LUI.

 | Only a single P-LUI/P-extent state shall be reported within a
 | single state request.

   P-LUIs and P-extents may report any of the following states
   under the listed conditions:

   Not Available - The selected P-LUI or P-extent is capable of being
   supported but no device is connected.

   Readying - The selected P-LUI or P-extent is being initialized and
   access to the P-LUI or P-extent is limited.

   Available - The selected P-LUI or P-extent is fully operational.

   Present - The selected P-LUI or P-extent is present but no other
   status is available.

   Broken - The selected P-LUI or P-extent is capable of being
   supported but it has failed.

   Not Supported - The SDA is not capable of supporting a device
   on the selected P-LUI or P-extent.

   3.5 Spare States

 | Only a single spare state shall be reported within a single
 | state request.

   Spares may report any of the following states under the listed
   conditions:

   Not Available - The selected spare is capable of being
   supported but has not been configured.

   Available - The selected spare is fully operational.

   Present - The selected spare is present but no other status is
   available.

   Spare in Use - The selected spare is being used.  In this
   state all data is still fully protected.

   Exposed - The selected spare is being used. In this state
   data is not protected.  In this state all data is still valid.

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

   3.6 C-LUI States

 | Only a single C-LUI shall be reported within a single state
 | request.

   Components(C-LUI) may report any of the following states under
   the listed conditions:

   Not Available - The selected C-LUI is capable of being
 | supported but no component is present.

   Readying - The selected C-LUI is being initialized and access
   to the C-LUI is limited.

   Available - The selected C-LUI is fully operational.

   Present - The selected C-LUI is present but no other status is
   available.

   Broken - The selected C-LUI is capable of being supported but
   it has failed.

   Not Supported - The SDA is not capable of supporting a
   component on the selected C-LUI.





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