SDA States and Types (94-041r1)

George Penokie GOP at rchvmp3.vnet.ibm.com
Tue Feb 8 08:19:06 PST 1994


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   Date:  Jan 13,1993                        X3T10/94-041 rev 1


   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:

   <<Editors note:  There have been several requests that the
   power supply, op panel, LED, etc.  not be listed as a
   peripheral device type.  One suggestion was to use the
   Peripheral qualifier for those types.  Another was to use the
   Device-type modifier.  This needs to be thought about so more.
   - GOP>>

.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 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.

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

   Available - The selected logical unit is fully operational.

   Implementors Note: A logical unit that has a redundancy type of
   no redundancy should report a state of available rather than
   exposed during normal operations.

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

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

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

   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 Power - Within the selected logical unit the power
 | is being supplied from an UPS (Uninterruptible Power Supply).

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

   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.

   Data Lost - Within the selected logical unit data has been
   lost.

   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.

   Not Supported - The SDA is not capable of supporting a device
   on the selected logical unit.

 | 4.0 Reporting of 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.
 |
 | 4.1 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 P-LUI 0 of the SDA.
 |
 | P-LUI 0 of an SDA may report any of the following states under
 | the listed conditions:
 |
 | Readying - The selected SDA is being initialized and access to
 | the SDA is limited.
 |
 | Available - The selected SDA is fully operational.
 |
 | Present - The selected SDA is present but no other status is
 | available.
 |
 | Error - Within the selected SDA 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 Power - Within the selected SDA the power is being
 | supplied from an UPS (Uninterruptible Power Supply).
 |
 | Degraded Performance - Within the selected SDA a part that
 | effects performance has failed.  In this state all data is
 | still fully protected (e.g.  cache failure, etc.)
 |
 | 4.2 Volume Set States
 |
 | 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.
 |
 | 4.3 Redundancy Group States
 |
 | 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.
 |
 | 4.4 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.
 |
 | 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.
 |
 | 4.5 Spare States
 |
 | 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.




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