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Versions: 00 01 02 03 04 05 06 07 08 09 RFC 7144

Storage Maintenance (StorM) Working Group                  F. Knight
Internet Draft                                                NetApp
Intended status: Standards Track                      M. Chadalapaka
Expires: June 2010                               Hewlett-Packard Co.
Updates: 3720, 5048                                    December 2009


      Internet Small Computer Systems Interface (iSCSI) Update
                  draft-ietf-storm-iscsi-sam-00.txt

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Copyright Notice

   Copyright (c) 2009 IETF Trust and the persons identified as the
   document authors. All rights reserved.




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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents in effect on the date of
   publication of this document (http://trustee.ietf.org/license-
   info). Please review these documents carefully, as they describe
   your rights and restrictions with respect to this document.

Abstract

   Internet Small Computer Systems Interface (iSCSI) is a SCSI
   transport protocol that maps the SCSI family of protocols onto
   TCP/IP. RFC 3720 defines the iSCSI protocol. The current iSCSI
   protocol (RFC 3720 and RFC 5048) is based on the SAM-2 version of
   the SCSI family of protocols). This document defines additions
   and changes to the iSCSI protocol to enabled additional features
   that were added to the SCSI family of protocols through SAM-3,
   SAM-4, and SAM-5.

   This document updates RFC 3720 and RFC 5048 and the text in this
   document supersedes the text in RFC 3720 and RFC 5048 when the
   two differ.




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    Table of Contents
1    Introduction.................................................... 4
2    Definitions, Acronyms, and Document Summary..................... 4
   2.1     Definitions .............................................. 4
   2.2     Acronyms ................................................. 4
   2.3     New Semantics ............................................ 5
3    UML Conventions................................................. 5
   3.2     Multiplicity notation .................................... 5
   3.3     Class diagram conventions ................................ 6
   3.4     Class diagram notation for associations .................. 6
   3.5     Class diagram notation for aggregations .................. 7
   3.6     Class diagram notation for generalizations ............... 8
4    iSCSI UML Model................................................. 9
5    Terminology Mapping............................................ 11
6    Negotiation of New Feature Use................................. 13
7    SCSI Commands.................................................. 13
   7.1     SCSI Command Additions .................................. 13
     7.1.1     Command Priority (byte 2) ........................... 13
   7.2     SCSI Response Additions ................................. 15
     7.2.1     Status Qualifier .................................... 15
     7.2.2     Data Segment - Sense and Response Data Segment ...... 16
8    Task Management Functions...................................... 16
   8.1     Existing Task Management Functions ...................... 16
   8.2     Task Management Function Additions ...................... 16
     8.2.1     LUN field ........................................... 18
     8.2.2     Referenced Task Tag ................................. 18
     8.2.3     RefCmdSN ............................................ 18
   8.3     Task Management Function Responses ...................... 19
     8.3.1     Task Management Function Response Additions ......... 20
   8.4     Task Management Requests Affecting Multiple Tasks ....... 20
9    Login/Text Operational Text Keys............................... 21
   9.1     New Operational Text Keys ............................... 21
     9.1.1     PDUFormatForSAMUpdate ............................... 21
10     IANA Considerations ......................................... 22
11     Security Considerations ..................................... 22
12     References .................................................. 23
13     Acknowledgements ............................................ 24




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1    Introduction

      The original [RFC3720] was built based on the SAM-2 model for
      SCSI. Several new features and capabilities have been added to
      the SCSI Architecture Model in the intervening years (SAM5 is now
      the current version of the SCSI Architecture Model). This
      document is not a complete revision of [RFC3720]. Instead, this
      document is intended as a companion document to [RFC3720] and
      [RFC5048].

      The text in this document, however, updates and supersedes the
      text in [RFC3720] and [RFC5048] whenever there is any conflict.

2     Definitions, Acronyms, and Document Summary

2.1   Definitions

      The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
      NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
      "OPTIONAL" in this document are to be interpreted as described in
      [RFC2119].

      -   iSCSI Node: The iSCSI Node represents a single iSCSI initiator
          or a single iSCSI target or both. There are one or more iSCSI
          Nodes within a Network Entity. The iSCSI Node is accessible
          via one or more Network Portals. An iSCSI Node is identified
          by its iSCSI Name. The separation of the iSCSI Name from the
          addresses used by and for the iSCSI Node allows multiple iSCSI
          Nodes to use the same address, and the same iSCSI Node to use
          multiple addresses.

<Note to reviewers: The above change from "a single iSCSI initiator
or a single iSCSI target" to "a single iSCSI initiator or a single
iSCSI target or both" does not impact the iSCSI MIB - as the "both"
portion is already accommodated there, where it makes statements
such as: "iscsiNode - An iSCSI node can act as an initiator, a
target, or both.", and "A portal can operate in one or both of two
roles: as a target portal and/or an initiator portal.".

In addition, RFCs 3271 also mentions that an iSCSI node may contain
both an iSCSI initiator and an iSCSI target.>

2.2   Acronyms

      SAM4      SCSI Architecture Model - 4
      SAM5      SCSI Architecture Model - 5
      SAM       SAM4 or SAM5
      UML       Unified Modeling Language




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2.3   New Semantics

      This document specifies new iSCSI semantics.   This section
      summarizes the contents of the document.

         Section 3: UML Conventions

         Section 4: The UML diagram of the iSCSI objects

         Section 5: The mapping of iSCSI objects to SAM5 objects

         Section 6: The protocol used to negotiate the use of the new
                    capabilities described in this document.

         Section 7: New Command operations

         Section 8: New Task Management Functions

3     UML Conventions

3.1   UML Conventions overview

      The SCSI Architecture Model (SAM) uses class diagrams and object
      diagrams with notation that is based on the Unified Modeling
      Language [UML]. Therefore, this document also uses UML to model
      the relationships for SCSI and iSCSI objects.

      A treatise on the graphical notation used in UML is beyond the
      scope of this document. However, given the use of ASCII drawing
      for UML static class diagrams, a description of the notational
      conventions used in this document is included in the remainder of
      this section.

3.2   Multiplicity notation

      Not specified   The number of instances of an attribute is not
                      specified.
      1               One instance of the class or attribute exists.
      0..*            Zero or more instances of the class or attribute
                      exist.
      1..*            One or more instances of the class or attribute
                      exist.
      0..1            Zero or one instance of the class or attribute
                      exists.
      n..m            n to m instances of the class or attribute exist
                      (e.g., 2..8).
      x, n..m         Multiple disjoint instances of the class or
                      attribute exist (e.g., 2, 8..15).




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3.3   Class diagram conventions

      +--------------+    +--------------+         +--------------+
      |  Class Name  |    |  Class Name  |         |  Class Name  |
      +--------------+    +--------------+         +--------------+
      |              |    |              |
      +--------------+    +--------------+
      |              |
      +--------------+
      The above three diagrams are examples of a   class with no
      attributes and with no operations.

      +-------------------+    +-------------------+
      |    Class Name     |    |    Class Name     |
      +-------------------+    +-------------------+
      |  attribute 01[1]  |    |  attribute 01[1]  |
      |  attribute 02[1]  |    |  attribute 02[1]  |
      +-------------------+    +-------------------+
      |                   |
      +-------------------+
      The above two diagrams are examples of a class with attributes
      and with no operations.

      +------------------------+
      |      Class Name        |
      +------------------------+
      |    attribute 01[1..*]  |
      |    attribute 02[1]     |
      +------------------------+
      |    operation 01()      |
      |    operation 02()      |
      +------------------------+
      The above diagram is an example of a class with attributes that
      have a specified multiplicity and operations.

3.4   Class diagram notation for associations

      +-----------------+
      |     Class A     |
      +-----------------+  association_name  +-----------------+
      | attribute 01[1] |<------------------>|     Class B     |
      | attribute 02[1] | 1..*          0..1 +-----------------+
      +-----------------+                    | attribute 03[1] |
      |  operation 1()  |                    +-----------------+
      +-----------------+
      The above diagram is an example where Class A knows about Class B
      (i.e., read as "Class A association_name ClassB") and Class B
      knows about Class A (i.e., read as "Class B association_name
      Class A"). The use of association_name is optional. The




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      multiplicity notation (1..* and 0..1) indicate the number of
      instances of the object.

      +--------------------+
      |      Class A       |
      +--------------------+              +--------------------+
      |  attribute 01[1]   |<-------------|      Class B       |
      |  attribute 02[1]   | 1       0..1 +--------------------+
      +--------------------+              |  attribute 03[1]   |
      |   operation 1()    |              +--------------------+
      +--------------------+
      The above diagram is an example where Class B knows about Class A
      (i.e., read as "Class B knows about Class A") but Class A does
      not know about Class B.

      +----------------------+
      |       Class A        |
      +----------------------+            +--------------------+
      |   attribute 01[1]    |----------->|      Class B       |
      |   attribute 02[1]    | 0..*     1 +--------------------+
      +----------------------+            | attribute 03[1]    |
      |    operation 1()     |            +--------------------+
      +----------------------+
      The above diagram is an example where Class A knows about Class B
      (i.e., read as "Class A knows about Class B") but Class B does
      not know about Class A.

3.5   Class diagram notation for aggregations

      +---------+             +--------+
      |  whole  |o------------|  part  |
      +---------+             +--------+
      The above diagram is an example where the part class is part of
      the whole class and may continue to exist even if the whole class
      is removed (i.e., read as "the whole contains the part").

      +---------+             +--------+
      |  whole  |@------------|  part  |
      +---------+             +--------+
      The above diagram is an example where the part class is part of
      the whole class, shall only belong to one whole class, and shall
      not continue to exist if the whole class is removed (i.e., read
      as "the whole contains the part").




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      +-------------+
      |             |
      +-------------+
         |       |
         + =(a)= +
         |       |
      The above diagram is an example where there is a constraint
      between the associations where the (a) footnote describes the
      constraint.

3.6   Class diagram notation for generalizations

      +---------------+
      | Superclass    |
      +-------^-------+
             /_\
              |
      +---------------+
      |    Subclass   |
      +---------------+
      The above diagram is an example where the subclass is a kind of
      superclass. A subclass shares all the attributes and operations
      of the superclass (i.e., the subclass inherits from the
      superclass).




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4   iSCSI UML Model

                 +----------------+
                 | Network Entity |
                 +----------------+
                      @ 1    @ 1
                      |      |
+---------------------+      |
|                            |
|                            | 0..*
|                  +------------------+
|                  |    iSCSI Node    |
|                  +------------------+
|                        @       @
|                        |       |
|           +------------+ =(a)= +------------+
|           |                                 |
|           | 0..1                            | 0..1
| +------------------------+     +----------------------+
| |    iSCSI Target Node   |     | iSCSI Initiator Node |
| +------------------------+     +----------------------+
|            @ 1                          @ 1
|            +---------------+            |
|                       1..* |            | 1..*
|                   +-----------------------------+
|                   |        Portal Group         |
|                   +-----------------------------+
|                                  O 1
|                                  |
|                                  | 1..*
|              1..* +------------------------+
+-------------------|     Network Portal     |
                    +------------------------+

    (a) Each instance of an iSCSI Node class MUST contain one iSCSI
        Target Node instance or one iSCSI Initiator Node instance, or
        both.




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                  +----------------+
                  | Network Entity |
                  +----------------+
                      @ 1        @ 1
                      |          |                 +-------------------+
+---------------------+          |                 |   iSCSI Session   |
|                                |                 +-------------------+
|                                | 0..*            |     SSID[1]       |
|                  +--------------------+          |     ISID[1]       |
|                  |     iSCSI Node     |          +-------------------+
|                  +--------------------+                   @ 1
|                  | iSCSI Node Name[1] |                   |
|                  |    Alias [0..1]    |                   | 0..*
|                  +--------------------+           +------------------+
|                  |                    |           | iSCSI Connection |
|                  +--------------------+           +------------------+
|                        @ 1       @ 1              |      CID[1]      |
|                        |         |                +------------------+
|           +------------+ ==(b)== +-----------+                  | 0..*
|           |                                  |                  |
|           | 1                                | 1                |
| +------------------------+         +------------------------+   |
| |   iSCSI Target Node    |         | iSCSI Initiator Node   |   |
| +------------------------+         +------------------------+   |
| | iSCSI Target name [1] |          |iSCSI Initiator Name [1]|   |
| +------------------------+         +------------------------+   |
|            @ 1                                 @ 1              |
|            |                                   |                |
|            | 1..*                              | 1..*           |
| +--------------------------+       +------------------------+   |
| |   Target Portal Group    |       | Initiator Portal Group |   |
| +--------------------------+       +------------------------+   |
| |Target Portal Group Tag[1]|       | Portal group tag[1]    |   |
| +--------------------------+       +------------------------+   |
|             o 1                                o 1              |
|             |                                  |                |
|             +-----------+            +---------+                |
|                    1..* |            | 1..*                     |
|                 +-------------------------+                     |
|                 |      Network Portal     |                     |
|                 +-------------------------+                     |
|            1..* |      IP Address [1]     | 1                   |
+-----------------|      TCP Port [0..1]    |<--------------------+
                  +-------------------------+

   (b) Each instance of an iSCSI Node class MUST contain one iSCSI
       Target Node instance or one iSCSI Initiator Node instance, or
       both.




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5   Terminology Mapping

    The iSCSI model (defined in [RFC3720]) uses different terminology
    than the SCSI Architecture Model. In some cases, iSCSI uses
    multiple terms to describe what in the SCSI Architecture Model is
    described with a single term. The iSCSI terms and SAM terms are
    not necessarily equivalent, but rather, the iSCSI terms represent
    examples of the objects or classes described in SAM as follows:

    +-----------------------------+---------------------------+
    | RFCxxx Terminology          | SAM Terminology           |
    +-----------------------------+---------------------------+
    | Network Entity              | none                      |
    +-----------------------------+---------------------------+
    | iSCSI Node                  | SCSI Device               |
    +-----------------------------+---------------------------+
    | iSCSI Name                  | SCSI Device Name          |
    +-----------------------------+---------------------------+
    | iSCSI Node Name             | SCSI Device Name          |
    +-----------------------------+---------------------------+
    | iSCSI Initiator Node        | SCSI Initiator Device     |
    +-----------------------------+---------------------------+
    | iSCSI Initiator Name        | SCSI Device Name          |
    +-----------------------------+---------------------------+
    | iSCSI Initiator Port Name   | SCSI Initiator Port Name  |
    | iSCSI Node Name + `,i,' +   |                           |
    | ISID                        |                           |
    +-----------------------------+---------------------------+
    | iSCSI Target Node           | SCSI Target Device        |
    +-----------------------------+---------------------------+
    | iSCSI Target Name           | SCSI Device Name          |
    +-----------------------------+---------------------------+
    | iSCSI Target Port Name      | SCSI Target Port Name     |
    | iSCSI Node Name + `,t,' +   |                           |
    | Target Portal Group Tag     |                           |
    +-----------------------------+---------------------------+
    | iSCSI Target Portal Group   | SCSI Target Port          |
    +-----------------------------+---------------------------+
    | iSCSI Initiator Node +      | SCSI Initiator Port       |
    | active ISID                 |                           |
    +-----------------------------+---------------------------+
    | iSCSI Initiator Name +      | I_T Nexus                 |
    | `,i,' + ISID, iSCSI Target  |                           |
    |   Name + `,t,' + Portal     |                           |
    |   Group Tag                 |                           |
    +-----------------------------+---------------------------+
    | Target Portal Group Tag     | Relative Port ID          |
    +-----------------------------+---------------------------+




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      --------------------------------------------------------
      RFC EDITORS NOTE: The above reference to [RFCxxx] should
      reference this RFC, and this note should be removed.
      --------------------------------------------------------

      The following diagram shows an example of a combination target
      device and initiator device. Such a configuration may exist
      in a target device that implements a SCSI Copy Manager. This
      example shows how a session that shares Network Portals within
      a Portal Group may be established (see Target Portal Group 1).
      In addition, this example shows the Initiator using a
      different Portal Group than the Target Portal Group, but the
      Initiator Portal group sharing Network Portal A with the
      Target Portal Group.


   ----------------------------IP Network---------------------
           |               |                    |
      +----|---------------|------+       +-----|-----------+
      | +----------+ +----------+ |       | +----------+    |
      | | Network  | | Network  | |       | | Network  |    |
      | | Portal A | | Portal B | |       | | Portal A |    |
      | +----------+ +----------+ |       | +----------+    |
      |    |    Target     |      |       |     | Initiator |
      |    |    Portal     |      |       |     | Portal    |
      |    |    Group 1    |      |       |     | Group 2   |
      +----|---------------|------+       +-----|-----------+
           |               |                    |
+----------|---------------|--------------------|--------------------+
| +--------|---------------|----+ +-------------|------------------+ |
| |+-------|---------------|---+| |+------------|-----------------+| |
| ||iSCSI Session (Target side)|| ||iSCSI Session (Initiator side)|| |
| ||                           || ||                              || |
| ||       (TSIH = 56)         || ||         (SSID = 48)          || |
| |+---------------------------+| |+------------------------------+| |
| |                             | |                                | |
| |     iSCSI Target Node       | |      iSCSI Initiator Node      | |
| +-----------------------------+ +--------------------------------+ |
|                          iSCSI Node                                |
|              (within Network Entity, not shown)                    |
+--------------------------------------------------------------------+




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6     Negotiation of New Feature Use

      The PDUFormatForSAMUpdate operational text key (see 9.1.1)
      containing a value of "Yes" MUST be negotiated to enable the use
      of features described in this RFC.

7     SCSI Commands

7.1   SCSI Command Additions

      The format of the SCSI Command PDU is:

    Byte/     0       |       1       |       2       |       3       |
       /              |               |               |               |
      |0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|
      +---------------+---------------+---------------+---------------+
     0|.|I| 0x01      |F|R|W|. .|ATTR | PRI   | Reserved              |
      +---------------+---------------+---------------+---------------+
     4|TotalAHSLength | DataSegmentLength                             |
      +---------------+---------------+---------------+---------------+
     8| Logical Unit Number (LUN)                                     |
      +                                                               +
    12|                                                               |
      +---------------+---------------+---------------+---------------+
    16| Initiator Task Tag                                            |
      +---------------+---------------+---------------+---------------+
    20| Expected Data Transfer Length                                 |
      +---------------+---------------+---------------+---------------+
    24| CmdSN                                                         |
      +---------------+---------------+---------------+---------------+
    28| ExpStatSN                                                     |
      +---------------+---------------+---------------+---------------+
    32/ SCSI Command Descriptor Block (CDB)                           /
     +/                                                               /
      +---------------+---------------+---------------+---------------+
    48/ AHS (Optional)                                                /
      +---------------+---------------+---------------+---------------+
     x/ Header Digest (Optional)                                      /
      +---------------+---------------+---------------+---------------+
     y/ (DataSegment, Command Data) (Optional)                        /
     +/                                                               /
      +---------------+---------------+---------------+---------------+
     z/ Data Digest (Optional)                                        /
      +---------------+---------------+---------------+---------------+

7.1.1 Command Priority (byte 2)




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   The Command Priority (PRI) specifies the relative scheduling
   importance of this task in relation to other SIMPLE tasks already
   in the task set (see [SAM4]).

   As defined in Section 10, iSCSI PDU Formats of [RFC3720],
   compliant senders already set this field to zero. A sender MUST
   NOT set this field to a value other than zero unless the
   PDUFormatForSAMUpdate text key defined in section 9.1.1 has been
   negotiated on the session with a value of "Yes".

   This field MUST be ignored by iSCSI targets unless the
   PDUFormatForSAMUpdate text key with a value of "Yes" as defined
   in section 9.1.1 was negotiated on the session.




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7.2   SCSI Response Additions

      The format of the SCSI Response PDU is:

  Byte/     0       |       1       |       2       |        3      |
     /              |               |               |               |
    |0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|
    +---------------+---------------+---------------+---------------+
   0|.|.| 0x21      |1|. .|o|u|O|U|.| Response      | Status        |
    +---------------+---------------+---------------+---------------+
   4|TotalAHSLength | DataSegmentLength                             |
    +---------------+---------------+---------------+---------------+
   8| Status Qualifier              | Reserved                      |
    +---------------+---------------+---------------+---------------+
  12| Reserved                                                      |
    +---------------+---------------+---------------+---------------+
  16| Initiator Task Tag                                            |
    +---------------+---------------+---------------+---------------+
  20| SNACK Tag or Reserved                                         |
    +---------------+---------------+---------------+---------------+
  24| StatSN                                                        |
    +---------------+---------------+---------------+---------------+
  28| ExpCmdSN                                                      |
    +---------------+---------------+---------------+---------------+
  32| MaxCmdSN                                                      |
    +---------------+---------------+---------------+---------------+
  36| ExpDataSN or Reserved                                         |
    +---------------+---------------+---------------+---------------+
  40| Bidirectional Read Residual Count or Reserved                 |
    +---------------+---------------+---------------+---------------+
  44| Residual Count or Reserved                                    |
    +---------------+---------------+---------------+---------------+
  48| Header-Digest (Optional)                                      |
    +---------------+---------------+---------------+---------------+
    / Data Segment (Optional)                                       /
   +/                                                               /
    +---------------+---------------+---------------+---------------+
    | Data-Digest (Optional)                                        |
    +---------------+---------------+---------------+---------------+

7.2.1 Status Qualifier

      The Status Qualifier provides additional status information (see
      [SAM4]).

      As defined in Section 10, iSCSI PDU Formats of [RFC3720],
      compliant senders already set this field to zero. Compliant
      senders MUST NOT set this field to a value other than zero unless




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      the PDUFormatForSAMUpdate text key with a value of "Yes" as
      defined in section 9.1.1 was negotiated on the session.

      This field MUST be ignored by receivers unless the
      PDUFormatForSAMUpdate text key with a value of "Yes" as defined
      in section 9.1.1 was negotiated on the session.

7.2.2 Data Segment - Sense and Response Data Segment

      Section 10.4.7 of [RFC3720] specifies that iSCSI targets MUST
      support and enable autosense. If Status is CHECK CONDITION
      (0x02), then the Data Segment MUST contain sense data for the
      failed command. While [RFC3720] does not make any statements
      about the state of the Data Segment when the Status is not CHECK
      CONDITION (0x02)(i.e., the Data Segment is not prohibited from
      containing sense data when the Status is not CHECK CONDITION),
      negotiation of the PDUFormatForSAMUpdate text key with a value of
      "Yes" as defined in section 9.1.1 explicitly indicates that the
      Data Segment MAY contain sense data at any time, no matter what
      value is set in the Status field.

8     Task Management Functions

8.1   Existing Task Management Functions

      Section 10.5 of [RFC3720] defines the semantics used to request
      SCSI Task Management Functions be performed. The following task
      management functions are defined:

       1   -   ABORT TASK
       2   -   ABORT TASK SET
       3   -   CLEAR ACA
       4   -   CLEAR TASK SET
       5   -   LOGICAL UNIT RESET
       6   -   TARGET WARM RESET
       7   -   TARGET COLD RESET
       8   -   TASK REASSIGN

8.2   Task Management Function Additions

      Additional task Management function codes are listed below. For
      a more detailed description of SCSI task management, see [SAM5].

           9 - QUERY TASK - determines if the task identified by the
           Referenced Task Tag field is present in the task set.

           10 - QUERY TASK SET - determine if any task is present in the
           task set.




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          11 - I_T NEXUS RESET - perform an I_T nexus loss function for
          the I_T nexus of each logical unit accessible through the I_T
          Nexus on which the task management function was received.

          12 - QUERY ASYNCHRONOUS EVENT - determine if there is a unit
          attention condition or a deferred error pending for the I_T
          nexus on which the task management function was received.

      Any compliant sender MUST NOT send these task management function
      requests unless the PDUFormatForSAMUpdate text key with a value
      of "Yes" as defined in section 9.1.1 was negotiated on the
      session.

      Any compliant initiator that sends any of the new task management
      functions defined in this section MUST also support all new task
      management function responses (see 8.3.1).

      For all of the task management functions detailed in this
      section, the Task Management function response MUST be returned
      as detailed in section 8.3 Task Management Function Response.

      The iSCSI target MUST ensure that no responses for the tasks
      covered by a task management function are delivered to the iSCSI
      initiator after the Task Management response except for a task
      covered by a TASK REASSIGN, QUERY TASK, or QUERY TASK SET.

      If a QUERY TASK is issued for a task created by an immediate
      command then RefCmdSN MUST be that of the Task Management request
      itself (i.e., CmdSN and RefCmdSN are equal); otherwise RefCmdSN
      MUST be set to the CmdSN of the task to be queried (lower than
      CmdSN).

      At the target a QUERY TASK function MUST NOT be executed on a
      Task Management request; such a request MUST result in Task
      Management response of "Function rejected".

      For the I_T NEXUS RESET function, the target device MUST respond
      to the function as defined in [SAM4]. Each logical unit
      accessible via the receiving I_T NEXUS MUST behave as dictated by
      the I_T nexus loss function in [SAM4] for the I_T nexus on which
      the task management function was received. The target device
      MUST drop all connections in the session over which this function
      is recevied. Independent of the DefaultTime2Wait and
      DefaultTime2Retain value applicable to the session over which
      this function is received, the target device MUST consider each
      participating connection in the session to have immediately timed
      out, leading to FREE state. The resulting timeouts cause the
      session timeout event defined in [RFC3720], which in turn
      triggers the I_T nexus loss notification to the SCSI layer as
      described in [RFC3720].



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8.2.1 LUN field

   This field is required for functions that address a specific LU
   (ABORT TASK, CLEAR TASK SET, ABORT TASK SET, CLEAR ACA, LOGICAL
   UNIT RESET, QUERY TASK, QUERY TASK SET, I_T NEXUS RESET, and
   QUERY ASYNCHRONOUS EVENT) and is reserved in all others.

8.2.2 Referenced Task Tag

   The Initiator Task Tag of the task to be aborted for the ABORT
   TASK function, reassigned for the TASK REASSIGN function, or
   queried for the QUERY TASK function. For all other functions
   this field MUST be set to the reserved value 0xffffffff.

8.2.3 RefCmdSN

   If a QUERY TASK is issued for a task created by an immediate
   command then RefCmdSN MUST be that of the Task Management request
   itself (i.e., CmdSN and RefCmdSN are equal).

   For a QUERY TASK of a task created by non-immediate command
   RefCmdSN MUST be set to the CmdSN of the task identified by the
   Referenced Task Tag field. Targets must use this field as
   described in section 10.6.1 of [RFC3720] when the task identified
   by the Referenced Task Tag field is not in the task set.




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8.3    Task Management Function Responses

  Byte/     0       |       1       |       2       |       3       |
     /              |               |               |               |
    |0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|0 1 2 3 4 5 6 7|
    +---------------+---------------+---------------+---------------+
   0|.|.| 0x22      |1| Reserved    | Response      | Reserved      |
    +---------------+---------------+---------------+---------------+
   4|TotalAHSLength | DataSegmentLength                             |
    +-----------------------------------------------+---------------+
   8| Additional Response Information               | Reserved      |
    +-----------------------------------------------+---------------+
  12| Reserved                                                      |
    +---------------+---------------+---------------+---------------+
  16| Initiator Task Tag                                            |
    +---------------+---------------+---------------+---------------+
  20| Reserved                                                      |
    +---------------+---------------+---------------+---------------+
  24| StatSN                                                        |
    +---------------+---------------+---------------+---------------+
  28| ExpCmdSN                                                      |
    +---------------+---------------+---------------+---------------+
  32| MaxCmdSN                                                      |
    +---------------+---------------+---------------+---------------+
  36/ Reserved                                                      /
   +/                                                               /
    +---------------+---------------+---------------+---------------+
  48| Header-Digest (Optional)                                      |
    +---------------+---------------+---------------+---------------+

      Section 10.6 of [RFC3720] defines the semantics used for
      responses to SCSI Task Management Functions. The following
      responses are defined in [RFC3720]:

         0 -   Function Complete.
         1 -   Task does not exist.
         2 -   LUN does not exist.
         3 -   Task still allegiant.
         4 -   Task allegiance reassignment not supported.
         5 -   Task management function not supported.
         6 -   Function authorization failed.
         255   - Function rejected.

      Responses to new task management functions (see 8.3.1) are listed
      below. In addition, a new task Management response is listed
      below. For a more detailed description of SCSI task management
      responses, see [SAM5].




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      For the functions QUERY TASK, QUERY TASK SET, I_T NEXUS RESET,
      and QUERY ASYNCHRONOUS EVENT, the target performs the requested
      Task Management function and sends a Task Management response
      back to the initiator.

8.3.1 Task Management Function Response Additions

      The new response is listed below:

         7 - Function succeeded.

      In symbolic terms Response value 7 maps to the SCSI service
      response of FUNCTION SUCCEEDED.

      The task management function response of function succeeded MUST
      be supported by an initiator that sends any of the new task
      management functions (see 8.2).

      For the QUERY TASK function, if the specified task is in the task
      set, then the target returns a Response value of Function
      succeeded and additional response information is returned as
      specified in [SAM5]. If the specified task is not in the task
      set, then the target returns a Response value of Function
      complete.

      For the QUERY TASK SET function, if there is any command present
      in the task set from the specified I_T_L nexus, then the target
      returns a Response value of Function succeeded. If there are no
      commands present in the task set from the specified I_T_L nexus,
      then the target returns a Response value of Function complete.

      For the I_T NEXUS RESET function, after completion of the events
      described in section 8.2 for this function, the target returns a
      Response value of Function complete. However, because the target
      drops all connections, the Service Response (defined by [SAM2])
      for this SCSI task management function may not be reliably
      delivered to the issuing initiator port.

      For the QUERY ASYNCHRONOUS EVENT, if there is a unit attention
      condition or deferred error pending for the specified I_T nexus,
      then the target returns a Response value of Function succeeded
      and additional response information is returned as specified in
      [SAM5]. If there is no unit attention or deferred error pending
      for the specified I_T nexus then the target returns a Response
      value of Function complete.

8.4   Task Management Requests Affecting Multiple Tasks

      Section 4.1 of [RFC5048] defines the notion of "affected tasks"
      in multi-task abort scenarios. This section adds to the list



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      include in that section by defining the tasks affected by the I_T
      NEXUS RESET function.

         I_T NEXUS RESET: All outstanding tasks received on the I_T
            nexus on which the function request was received for all
            logical units accessible to the I_T nexus.

      Section 4.1.2 of [RFC5048] and section 4.1.3 of [RFC5048]
      identify semantics for task management functions that involve
      multi-task abort operations. If an iSCSI implementation supports
      the I_T NEXUS RESET function, it MUST also support the protocol
      behavior as defined in those sections and follow the sequence of
      actions as described in those sections when processing the I_T
      NEXUS RESET function.

9     Login/Text Operational Text Keys

9.1   New Operational Text Keys

9.1.1 PDUFormatForSAMUpdate

      Use: LO
      Irrelevant when: SessionType = Discovery
      Senders: Initiator and Target
      Scope: SW

      PDUFormatForSAMUpdate=<Boolean-value>

      Default is No.
      Result function is AND.

      This key is used to negotiate the RFC compliance level applicable
      to the iSCSI session once the session is in full feature phase.

      If the negotiation answer is ignored by the acceptor, or the
      answer from the remote iSCSI end point is key=NotUnderstood, then
      the features defined in this RFC MUST NOT be used.

      Note that operational value of "Yes" for this key on an iSCSI
      session does not influence the SCSI level features in any way on
      that I_T nexus. An operational value of "Yes" for this key
      permits the iSCSI-related features defined in this document to be
      used on all connections on this iSCSI session. SCSI level hand-
      shakes (e.g. commands, mode pages) eventually determine the
      existence or lack of various SAM features available for the I_T
      nexus between the two SCSI end points). To summarize,
      negotiation of this key to "Yes" is a necessary but not a
      sufficient condition of SAM-4 compliant feature usage at the SCSI
      protocol level.




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10   Security Considerations

     At the time of writing this document does not introduce any new
     security considerations other than those described in [RFC3720].
     Consequently, all the iSCSI-related security text in [RFC3723] is
     also directly applicable to this document.

11   IANA Considerations

     This document modifies or creates a number of iSCSI-related
     registries. The following iSCSI-related registries are modified:

     1. iSCSI Task Management Functions Codes

        Name of the existing registry: "iSCSI TMF Codes"

        Additional entries:

        9, QUERY TASK, [RFCxxx]

        10, QUERY TASK SET, [RFCxxx]

        11, I_T NEXUS RESET, [RFCxxx]

        12, QUERY ASYNCHRONOUS EVENT, [RFCxxx]

        ---------------------------------------------------------
        RFC EDITORS NOTE: The above reference to [RFCxxx] should
        reference this RFC, and this note should be removed.
        ---------------------------------------------------------

     2. iSCSI Login/Text Keys

        Name of the existing registry: "iSCSI Text Keys"

        Additional entry:

        PDUFormatForSAMUpdate, [RFCxxx]

        ---------------------------------------------------------
        RFC EDITORS NOTE: The above reference to [RFCxxx] should
        reference this RFC, and this note should be removed.
        ---------------------------------------------------------

     This document creates the following iSCSI-related registries for
     IANA to manage.

     3. iSCSI Task Management Response Codes

        Name of new registry: "iSCSI TMF Response Codes"



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       Namespace details: Numerical values that can fit in 8 bits.

       Information that must be provided to assign a new value: An
       IESG-approved specification defining the semantics and
       interoperability requirements of the proposed new value and
       the fields to be recorded in the registry.

       Assignment policy:

       If the requested value is not already assigned, it may be
       assigned to the requester.

       8-254: Range reserved by iANA for assignment in this registry.

       Fields to record in the registry: Assigned value, Operation
       Name, and its associated RFC reference.

       0x0, Function complete, [RFC3720]

       0x1, Task does not exist, [RFC3720]

       0x2, LUN does not exist, [RFC3720]

       0x3, Task still allegiant, [RFC3720]

       0x4, Task allegiance reassignment not supported, [RFC3720]

       0x5, Task management function not supported, [RFC3720]

       0x6, Function authorization failed, [RFC3720]

       0x7, Function succeeded, [RFCxxx]

       255, Function rejected, [RFC3720]

       ------------------------------------------------------------
       RFC EDITORS NOTE: The above reference to [RFCxxx] should
       reference this RFC, and this note should be removed.
       ------------------------------------------------------------

       Allocation Policy:

       Standards Action ([IANA])

12     References

12.1   Normative References




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     [RFC2119]   Bradner, S. "Key Words for use in RFCs to Indicate
                 Requirement Levels", BCP 14, RFC 2119, March 1997.

     [RFC3720]   Satran, J., Meth, K., Sapuntzakis, C., Chadalapaka,
                 M., and E. Zeidner, "Internet Small Computer Systems
                 Interface (iSCSI)", RFC 3720, April 2004.

     [RFC3723]   Aboba, B., Tseng, J., Walker, J., Rangan, V., and
                 Travostino, F., "Securing Block Storage Protocols
                 over IP", RFC 3723, April 2004.

     [RFC5048]   Chadalapaka, M., "Internet Small Computer System
                 Interface (iSCSI) Corrections and Clarifications",
                 RFC 5048, October 2007.

     [IANA]      Narten, T. and H. Alvestrand, "Guidelines for Writing
                 an IANA Considerations Section in RFCs", BCP 26, RFC
                 5226, May 2008.

     [UML]       ISO/IEC 19501, Unified Modeling Language
                 Specification Version 1.4.2.

     [SAM2]      T10/1157D, SCSI Architecture Model - 2 (SAM-2).

     [SAM4]      ISO/IEC 14776-414, SCSI Architecture Model - 4 (SAM-
                 4).

12.2 Informative References

     [SAM5]      T10/2104D rev xxx, SCSI Architecture Model - 5 (SAM-
                 5), Work in Progress. <we still have to figure out
                 what to do with this - normative vs. informative vs.
                 get T10 to stabilize a version for us to reference
                 vs. other ideas...>

12.3 Additional Reference Sources

     For more information on the SCSI Architecture Model, contact the
     T10 group at http://www.t10.org.

     For more information on the UML specification, contact the Object
     Modeling Group at http://www.omg.org.

13   Acknowledgements

     The Storage Maintenance (STORM) Working Group in the Transport
     Area of the IETF has been responsible for defining these
     additions to the iSCSI protocol (apart from other relevant IP
     Storage protocols). The editor acknowledges the contributions of
     the entire working group.



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   The following individuals directly contributed to identifying
   [RFCxxx] issues and/or suggesting resolutions to the issues
   clarified in this document: Mallikarjun Chadalapaka, David Black,
   Rob Elliott. This document benefited from all of these
   contributions.

      ------------------------------------------------------------
      RFC EDITORS NOTE: The above reference to [RFCxxx] should
      reference this RFC, and this note should be removed.
      ------------------------------------------------------------

   Editor's Address
   Frederick Knight
   7301 Kit Creek Road
   P.O. Box 13917
   Research Triangle Park, NC    27709
   Phone: +1-919-476-5362
   Email: knight@netapp.com




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