Rev 1 of Device Identification Page Proposal

Lohmeyer, John JLOHMEYE at cosmpdaero.ftcollinsco.ncr.com
Thu Oct 12 15:42:00 PDT 1995


                                                               X3T10/95-240 
r1



     Date: October 12, 1995

       To: X3T10 Committee

     From: John Lohmeyer, Principal member from Symbios Logic

  Subject: Device Identification Page Proposal (Rev 1)


At the July `95 SCSI working group meeting, I presented revision 0 of this
proposal.  Rev 0 principally dealt with retrieving SCAM strings and defined 
an
new mode select/sense page.  With the input I received at that meeting plus
various discussions since the meeting, I have prepared revision 1.  This
proposal would define a new Vital Product Data page and includes the ability
to return multiple identifiers (e.g., a device may have both an X3T10
identifier and an IEEE identifier).

Proposed changes to SPC are to replace the existing section 8.4.3 with the
following paragraphs and to renumber the existing sections 8.4.3--8.4.5 to
8.4.4--8.4.6, respectively.  All references to these sections would need to 
be
adjusted, Table 93 would need to be updated, and subsequent tables would 
need
to be renumbered.

8.3.4 Device identification page

The optional device identification page (see table xx) provides the means to
retrieve zero or more identification descriptors for the logical unit.
Logical units may have more than one identification descriptor if both X3T10
and IEEE identifiers are supported or if group identifiers are supported in
addition to device identifiers.

Device identifiers are intended to be assigned to the device (e.g., a disk
drive) and not to the currently mounted media in the case of removable media
devices.  Media identification is outside the scope of this standard.  It is
expected that operating systems will make use of the device and group
identifiers during system configuration activities to determine whether
alternate paths exist for the same device.

                     Table xx - Device identification page
+=====-========-========-========-========-========-========-========-======  
==+
|  Bit|   7    |   6    |   5    |   4    |   3    |   2    |   1    |   0 
   |
|Byte |        |        |        |        |        |        |        | 
       |
|=====+==========================+==========================================  
==|
| 0   | Peripheral qualifier     |           Peripheral device type 
          |
|-----+---------------------------------------------------------------------  
 --|
| 1   |                           Page code (83h) 
                            |
|-----+---------------------------------------------------------------------  
 --|
| 2   |                           Reserved 
                                   |
|-----+---------------------------------------------------------------------  
 --|
| 3   |                           Page length (n-3) 
                          |
|=====+=====================================================================  
==|
|     |                           Identification descriptor list 
             |
|=====+=====================================================================  
==|
| 4   | (MSB) 
                                                                |
|- - -+- -                        Identification descriptor (0)            - 
 -|
|     | 
                                                                (LSB) |
|-----+---------------------------------------------------------------------  
 --|
|     |                           . 
                                          |
|     |                           . 
                                          |
|     |                           . 
                                          |
|-----+---------------------------------------------------------------------  
 --|
|     | (MSB) 
                                                                |
|- - -+- -                        Identification descriptor (last)         - 
 -|
| n   | 
                                                                (LSB) |
+===========================================================================  
==+

Each Identification descriptor (see table xx+1) contains information
identifying the device or group.

                    Table xx+1 - Identification descriptor
+=====-========-========-========-========-========-========-========-======  
==+
|  Bit|   7    |   6    |   5    |   4    |   3    |   2    |   1    |   0 
   |
|Byte |        |        |        |        |        |        |        | 
       |
|=====+==========================+==========================================  
==|
| 0   |        Identifier category        |         Code set 
                 |
|-----+---------------------------------------------------------------------  
 --|
| 1   |        Reserved                   |         Identifier type 
          |
|-----+---------------------------------------------------------------------  
 --|
| 2   |                           Reserved 
                                   |
|-----+---------------------------------------------------------------------  
 --|
| 3   |                           Identifier length (m-3) 
                    |
|-----+---------------------------------------------------------------------  
 --|
| 4   | (MSB) 
                                                                |
|- - -+- -                        Identifier                               - 
 -|
| m   | 
                                                                (LSB) |
+===========================================================================  
==+

A value of 0 in the identification category field specifies that this
identification descriptor contains an identification for the logical unit. 
 If
the logical unit is accessible through any other path, it shall return the
same identification.

A value of 1 in the identification category field specifies that this
identification descriptor contains a group identification for the logical
unit.  If any other logical unit accessible by the system reports the same
group identification, then it belongs to the same group and manages the same
resources (e.g., it may be an alternate path to the same device or devices).
This standard does not address how group identifiers are established or
managed.

Values of 2 through Fh in the identification category field are reserved.

The code set field specifies the code set used for the identifier field as
described in table xx+2.  This field is intended to be an aid to software 
that
displays the identifier field.

                             Table xx+2 - Code set
+=======+===================================================================  
==+
| Value | Description 
                                                        |
+=======+===================================================================  
==+
|   0   | Reserved 
                                                           |
+-------+-------------------------------------------------------------------  
 --+
|   1   | The identifier field contains binary values. 
                       |
+-------+-------------------------------------------------------------------  
 --+
|   2   | The identifier field only contains ASCII graphic codes (i.e., code 
 |
|       | values 20h through 7Eh). 
                                           |
+-------+-------------------------------------------------------------------  
 --+
| 3-Fh  | Reserved 
                                                           |
+===========================================================================  
==+

The identifier type field specifies the format and assignment authority for
the identifier as described in table xx+3.

                         Table xx+3 - Identifier type
+=======+===================================================================  
==+
| Value | Description 
                                                        |
+=======+===================================================================  
==+
|   0   | No assignment authority was used and consequently the identifier 
   |
|       | may not be globally unique. 
                                        |
+-------+-------------------------------------------------------------------  
 --+
|   1   | The first 8 bytes of the identifier field are an X3T10 Vendor ID 
   |
|       | (see annex C).  The organization assigned to the X3T10 Vendor ID 
is |
|       | responsible for ensuring that the remainder of the identifier 
field |
|       | is unique.  One recommended method of constructing the remainder 
of |
|       | the identifier field is to concatenate the product identification 
  |
|       | field from the standard INQUIRY data field and the product serial 
  |
|       | number field from the unit serial number page. 
                     |
+-------+-------------------------------------------------------------------  
 --+
|   2   | The identifier field contains an IEEE 64-bit identifier.  In this 
  |
|       | case, the identifier length field shall be set to 8.  Note that 
the |
|       | IEEE guidelines for 64-bit global identifiers specifies a method 
   |
|       | for unambiguously encapsulating 48-bit identifiers as 64-bit 
       |
|       | identifiers. 
                                                       |
+-------+-------------------------------------------------------------------  
 --+
|   3   | The identifier field contains an FC-PH 64-bit identifier as 
defined |
|       | in X3.230-1994. 
                                                    |
+-------+-------------------------------------------------------------------  
 --+
| 4-Fh  | Reserved 
                                                           |
+===========================================================================  
==+

The identifier length field specifies the length in bytes of the identifier.
If the allocation length field of the command descriptor block is too small 
to
transfer all of the identifier, the identifier length shall not be adjusted 
to
reflect the truncation.

The identifier field contains the identifier as described by the identifier
category, identifier type, code set, and identifier length fields.


 --
John Lohmeyer             E-Mail:  john.lohmeyer at symbios.com
Symbios Logic Inc.         Voice:  719-573-3362
1635 Aeroplaza Dr.           Fax:  719-573-3037
Colo Spgs, CO 80916     SCSI BBS:  719-574-0424 300--14400 baud




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