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+Internet Engineering Task Force (IETF)                         F. Knight
+Request for Comments: 7144                                        NetApp
+Category: Standards Track                                 M. Chadalapaka
+ISSN: 2070-1721                                                Microsoft
+                                                              April 2014
+
+
+            Internet Small Computer System Interface (iSCSI)
+                          SCSI Features Update
+
+Abstract
+
+   Internet Small Computer System Interface (iSCSI) is a SCSI
+   transport protocol that maps the SCSI family of protocols onto
+   TCP/IP.  The iSCSI protocol as specified in RFC 7143 (and as
+   previously specified by the combination of RFC 3720 and RFC
+   5048) is based on the SAM-2 (SCSI Architecture Model - 2)
+   version of the SCSI family of protocols.  This document
+   defines enhancements to the iSCSI protocol to support certain
+   additional features of the SCSI protocol that were defined in
+   SAM-3, SAM-4, and SAM-5.
+
+   This document is a companion document to RFC 7143.
+
+Status of This Memo
+
+   This is an Internet Standards Track document.
+
+   This document is a product of the Internet Engineering Task Force
+   (IETF).  It represents the consensus of the IETF community.  It has
+   received public review and has been approved for publication by
+   the Internet Engineering Steering Group (IESG).  Further
+   information on Internet Standards is available in Section 2 of
+   RFC 5741.
+
+   Information about the current status of this document, any
+   errata, and how to provide feedback on it may be obtained at
+   http://www.rfc-editor.org/info/rfc7144.
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+Knight & Chadalapaka         Standards Track                    [Page 1]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
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+Copyright Notice
+
+   Copyright (c) 2014 IETF Trust and the persons identified as the
+   document authors.  All rights reserved.
+
+   This document is subject to BCP 78 and the IETF Trust's Legal
+   Provisions Relating to IETF Documents
+   (http://trustee.ietf.org/license-info) in effect on the date of
+   publication of this document.  Please review these documents
+   carefully, as they describe your rights and restrictions with respect
+   to this document.  Code Components extracted from this document must
+   include Simplified BSD License text as described in Section 4.e of
+   the Trust Legal Provisions and are provided without warranty as
+   described in the Simplified BSD License.
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+Knight & Chadalapaka         Standards Track                    [Page 2]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+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 ..............................................4
+   3. Terminology Mapping .............................................5
+   4. New Feature Use .................................................7
+      4.1. Negotiation of New Feature Use .............................7
+      4.2. Impact on Standard INQUIRY Data - iSCSI Version
+           Descriptors ................................................8
+   5. SCSI Commands ...................................................9
+      5.1. SCSI Command Additions .....................................9
+           5.1.1. Command Priority (Byte 2) ..........................10
+      5.2. SCSI Response Additions ...................................11
+           5.2.1. Status Qualifier ...................................12
+           5.2.2. Data Segment - Sense and Response Data Segment .....12
+   6. Task Management Functions ......................................13
+      6.1. Task Management Function Request PDU ......................13
+      6.2. Existing Task Management Functions ........................14
+      6.3. Task Management Function Additions ........................14
+           6.3.1. LUN Field ..........................................15
+           6.3.2. Referenced Task Tag ................................16
+           6.3.3. RefCmdSN ...........................................16
+      6.4. Task Management Function Responses ........................17
+           6.4.1. Task Management Function Response PDU ..............17
+           6.4.2. Task Management Function Response Additions ........18
+      6.5. Task Management Requests Affecting Multiple Tasks .........19
+   7. Login/Text Operational Text Keys ...............................19
+      7.1. New Operational Text Keys .................................19
+           7.1.1. iSCSIProtocolLevel .................................19
+   8. Security Considerations ........................................20
+   9. IANA Considerations ............................................21
+   10. References ....................................................24
+      10.1. Normative References .....................................24
+      10.2. Informative References ...................................24
+   11. Acknowledgements ..............................................24
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+Knight & Chadalapaka         Standards Track                    [Page 3]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+1.  Introduction
+
+   The original iSCSI protocol [RFC3720] was built based on the [SAM2]
+   model for SCSI.  Several new features and capabilities have been
+   added to the SCSI Architecture Model in the intervening years (at the
+   time of publication of this document, SAM-5 was 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 RFC 7143; this document may also be used as a
+   companion document to the combination of [RFC3720] and [RFC5048],
+   although both of those RFCs have been obsoleted by [RFC7143].
+
+   For more information on the SCSI Architecture Model and SCSI Primary
+   Commands - 4, contact the INCITS T10 Technical Committee for SCSI
+   Storage Interfaces at <http://www.t10.org>.
+
+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].
+
+2.2.  Acronyms
+
+   ACA      Auto Contingent Allegiance
+   AHS      Additional Header Segment
+   ISID     Initiator Session Identifier
+   LU       Logical Unit
+   PDU      Protocol Data Unit
+   SAM-5    SCSI Architecture Model - 5 (see [SAM5])
+   TSIH     Target Session Identifying Handle
+
+2.3.  New Semantics
+
+   This document specifies new iSCSI semantics.  This section summarizes
+   the contents of the document.
+
+      Section 3:  The mapping of iSCSI objects to SAM-5 objects
+                  The iSCSI node may contain both initiator and target
+                  capabilities.
+
+      Section 4:  New feature use
+                  New features need negotiation for use.  The
+                  negotiation may have an impact on standard INQUIRY
+                  data.
+
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+
+
+Knight & Chadalapaka         Standards Track                    [Page 4]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+      Section 5:  New command operations
+                  The PRI field for SCSI command priority has been added
+                  to the SCSI Command PDU (see Section 5.1.1).  The
+                  Status Qualifier field has been added to the SCSI
+                  Response PDU (see Section 5.2.1).  Sense data may be
+                  returned (via Autosense) for any SCSI status, not just
+                  CHECK CONDITION (see Section 5.2.2).
+
+      Section 6:  New task management functions
+                  Four new task management functions (QUERY TASK, QUERY
+                  TASK SET, I_T NEXUS RESET, and QUERY ASYNCHRONOUS
+                  EVENT) have been added (see Section 6.3).  A new
+                  "Function succeeded" response has been added (see
+                  Section 6.4.2).
+
+      Section 7:  New negotiation key
+                  A new negotiation key has been added to enable the use
+                  of the new features in Sections 5 and 6.
+
+3.  Terminology Mapping
+
+   The iSCSI model (defined in [RFC7143]) 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-5 terms are not
+   necessarily equivalent, but rather, the iSCSI terms represent
+   examples of the objects or classes described in SAM-5 as follows:
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+Knight & Chadalapaka         Standards Track                    [Page 5]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+       Terminology in RFC 7143     | Terminology in SAM-5
+     +-----------------------------+---------------------------+
+     | 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        | SCSI Initiator Port       |
+     | Identifier; (i.e., iSCSI    | Identifier                |
+     | Node Name + ,,,i, + ISID)** |                           |
+     +-----------------------------+---------------------------+
+     | iSCSI Initiator Port Name;  | SCSI Initiator Port Name  |
+     | (i.e., iSCSI Node Name +    |                           |
+     | ,,,i, + ISID)**             |                           |
+     +-----------------------------+---------------------------+
+     | iSCSI Target Node           | SCSI Target Device        |
+     +-----------------------------+---------------------------+
+     | iSCSI Target Name           | SCSI Device Name          |
+     +-----------------------------+---------------------------+
+     | iSCSI Target Port           | SCSI Target Port          |
+     | Identifier; (i.e., iSCSI    | Identifier                |
+     | Node Name + ,,,t, +         |                           |
+     | Target Portal Group Tag)**  |                           |
+     +-----------------------------+---------------------------+
+     | iSCSI Target Port Name;     | SCSI Target Port Name     |
+     | (i.e., iSCSI Node Name +    |                           |
+     | ,,,t, + Target Portal       |                           |
+     | Group Tag)**                |                           |
+     +-----------------------------+---------------------------+
+     | iSCSI Target Portal Group   | SCSI Target Port          |
+     +-----------------------------+---------------------------+
+     | iSCSI Initiator Name +      | I_T Nexus Identifier      |
+     | ',i,' + ISID + iSCSI        |                           |
+     | Target Name + ',t,' +       |                           |
+     | Target Portal Group Tag     |                           |
+     +-----------------------------+---------------------------+
+     | Target Portal Group Tag     | Relative Port ID          |
+     +-----------------------------+---------------------------+
+
+   ** The text encoding of the ISID value and the Target Portal Group
+      Tag value includes an initial ,,0X or ,,0x (see [RFC7143]).
+
+
+
+Knight & Chadalapaka         Standards Track                    [Page 6]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+   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)                    |
+  +--------------------------------------------------------------------+
+
+4.  New Feature Use
+
+4.1.  Negotiation of New Feature Use
+
+   The iSCSIProtocolLevel operational text key (see Section 7.1.1)
+   containing a value of "2" MUST be negotiated to enable the use of
+   features described in this RFC.
+
+   This is an iSCSI negotiation mechanism that enabled iSCSI support for
+   corresponding SCSI capabilities (see [SAM5] and [SPC4]).  For this
+   reason, negotiation of this key to a value of "2" is necessary but
+   not sufficient for use of the SCSI capabilities enabled by the iSCSI
+   features in this RFC.
+
+
+
+Knight & Chadalapaka         Standards Track                    [Page 7]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+   For example, an iSCSI implementation may negotiate this new key to
+   "2" but respond to the new task management functions (see Section
+   6.3) with "Task management function not supported" (which indicates a
+   SCSI error that prevents the function from being performed).  In
+   contrast, if the key is negotiated to "2", an iSCSI implementation
+   MUST NOT reject a Task Management Function Request PDU that requests
+   one of the new task management functions (as such a reject would
+   report an iSCSI protocol error).
+
+4.2.  Impact on Standard INQUIRY Data - iSCSI Version Descriptors
+
+   The negotiated value of the iSCSIProtocolLevel key is an increment
+   from the base iSCSI version descriptor value (0960h); see [SPC4].  If
+   the SCSI device server returns an iSCSI version descriptor in the
+   standard INQUIRY data, then the value returned in that iSCSI version
+   descriptor MUST be set to the sum of the base value (0960h) plus the
+   negotiated value of the iSCSIProtocolLevel key.  (For example, if the
+   negotiated iSCSIProtocolLevel=2, then if an iSCSI version descriptor
+   is returned in the standard INQUIRY data, it is set to 0962h.)
+
+   In support of this functionality, INCITS Technical Committee T10,
+   which is responsible for SCSI standards, has assigned SCSI version
+   descriptor codes 0961h-097Fh to RFC 7144 for IANA to manage via the
+   values 1-31 of the iSCSIProtocolLevel key; see Section 9.  The "No
+   version claimed" description for the value 0 of the
+   iSCSIProtocolLevel key corresponds to the existing T10 assignment of
+   the 0960h SCSI version descriptor code to "iSCSI (no version
+   claimed)" -- for this reason, the assignment of the value 0 in the
+   IANA registry for the iSCSIProtocolLevel key must not be changed.
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+Knight & Chadalapaka         Standards Track                    [Page 8]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+5.  SCSI Commands
+
+5.1.  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)                                        /
+     +---------------+---------------+---------------+---------------+
+
+   The SCSI Command PDU above is duplicated from [RFC7143] for reference
+   to show the PRI field.  For any field other than the PRI field, the
+   text in [RFC7143] supersedes the text in Section 5.1 of this document
+   in the event the two documents conflict.
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+Knight & Chadalapaka         Standards Track                    [Page 9]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+5.1.1.  Command Priority (Byte 2)
+
+   The Command Priority (PRI) is a four-bit field that specifies the
+   relative scheduling importance of this command in relation to other
+   commands already in the task set with SIMPLE task attributes (see
+   [SAM5]).
+
+   Section 11 ("iSCSI PDU Formats") of [RFC7143] requires that senders
+   set this field to zero.  A sender MUST NOT set this field to a value
+   other than zero unless the iSCSIProtocolLevel text key defined in
+   Section 7.1.1 has been negotiated on the session with a value of "2".
+
+   This field MUST be ignored by iSCSI targets unless the
+   iSCSIProtocolLevel text key with a value of "2" as defined in Section
+   7.1.1 was negotiated on the session.
+
+   See [SAM5] for additional considerations on the use of the Command
+   Priority field.
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+Knight & Chadalapaka         Standards Track                   [Page 10]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+5.2.  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)                                        |
+      +---------------+---------------+---------------+---------------+
+
+   The SCSI Response PDU above is duplicated from [RFC7143] for
+   reference to show the Status Qualifier field.  For any field other
+   than the Status field, the Status Qualifier field, and the Data
+   Segment - Sense and Response Data Segment field, the text in
+   [RFC7143] supersedes the text in Section 5.2 of this document in the
+   event the two documents conflict.
+
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+
+Knight & Chadalapaka         Standards Track                   [Page 11]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+5.2.1.  Status Qualifier
+
+   The Status Qualifier provides additional status information (see
+   [SAM5]).
+
+   As defined in Section 11 ("iSCSI PDU Formats") of [RFC7143],
+   compliant senders already set this field to zero.  Compliant senders
+   MUST NOT set this field to a value other than zero unless the
+   iSCSIProtocolLevel text key with a value of "2" as defined in Section
+   7.1.1 was negotiated on the session.
+
+   This field MUST be ignored by receivers unless the iSCSIProtocolLevel
+   text key with a value of "2" as defined in Section 7.1.1 was
+   negotiated on the session.
+
+5.2.2.  Data Segment - Sense and Response Data Segment
+
+   Section 11.4.7 of [RFC7143] 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
+   [RFC7143] 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 iSCSIProtocolLevel text
+   key with a value of "2" as defined in Section 7.1.1 explicitly
+   indicates that the Data Segment MAY contain sense data at any time,
+   no matter what value is set in the Status field.
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+Knight & Chadalapaka         Standards Track                   [Page 12]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+6.  Task Management Functions
+
+6.1.  Task Management Function Request PDU
+
+    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| 0x02      |1| Function    | Reserved                      |
+      +---------------+---------------+---------------+---------------+
+     4|TotalAHSLength | DataSegmentLength                             |
+      +---------------+---------------+---------------+---------------+
+     8| Logical Unit Number (LUN)                                     |
+      +                                                               +
+    12|                                                               |
+      +---------------+---------------+---------------+---------------+
+    16| Initiator Task Tag                                            |
+      +---------------+---------------+---------------+---------------+
+    20| Referenced Task Tag or 0xffffffff                             |
+      +---------------+---------------+---------------+---------------+
+    24| CmdSN                                                         |
+      +---------------+---------------+---------------+---------------+
+    28| ExpStatSN                                                     |
+      +---------------+---------------+---------------+---------------+
+    32| RefCmdSN or Reserved                                          |
+      +---------------+---------------+---------------+---------------+
+    36| ExpDataSN or Reserved                                         |
+      +---------------+---------------+---------------+---------------+
+    40| Reserved                                                      /
+     +/                                                               /
+      +---------------+---------------+---------------+---------------+
+    48| Header-Digest (Optional)                                      |
+      +---------------+---------------+---------------+---------------+
+
+   The Task Management Function Request PDU above is duplicated from
+   [RFC7143] for reference only.  [RFC7143] supersedes the text in
+   Sections 6.1 and 6.2 of this document in the event the two documents
+   conflict.
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+Knight & Chadalapaka         Standards Track                   [Page 13]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+6.2.  Existing Task Management Functions
+
+   Section 11.5 of [RFC7143] defines the semantics used to request that
+   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
+
+6.3.  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 - determine if the command identified by the
+         Referenced Task Tag field is present in the task set.
+
+      10 - QUERY TASK SET - determine if any command is present in the
+         task set for the I_T_L Nexus on which the task management
+         function was received.
+
+      11 - I_T NEXUS RESET - perform an I_T nexus loss function (see
+         [SAM5]) for 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_L
+         nexus on which the task management function was received.
+
+   These task management function requests MUST NOT be sent unless the
+   iSCSIProtocolLevel text key with a value of "2" as defined in Section
+   7.1.1 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 (as specified in Section 6.4.2).
+
+   For all of the task management functions detailed in this section,
+   the Task Management Function Response MUST be returned as detailed in
+   Section 6.4.
+
+
+
+
+
+Knight & Chadalapaka         Standards Track                   [Page 14]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+   The iSCSI target MUST ensure that no responses for the commands
+   covered by a task management function are sent to the iSCSI initiator
+   port after the Task Management response except for commands 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).
+
+   If the connection is still active (it is not undergoing an implicit
+   or explicit logout), QUERY TASK MUST be issued on the same connection
+   to which the task to be queried is allegiant at the time the Task
+   Management request is issued.  If the connection is implicitly or
+   explicitly logged out (i.e., no other request will be issued on the
+   failing connection and no other response will be received on the
+   failing connection), then a QUERY TASK function request may be issued
+   on another connection.  This Task Management request will then
+   establish a new allegiance for the command being queried.
+
+   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 [SAM5].  Each logical unit accessible via
+   the receiving I_T NEXUS MUST behave as dictated by the I_T nexus loss
+   function in [SAM5] 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 received.  Independent of
+   the DefaultTime2Wait and DefaultTime2Retain values 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 [RFC7143], which in turn
+   triggers the I_T nexus loss notification to the SCSI layer as
+   described in [RFC7143].
+
+6.3.1.  LUN Field
+
+   This field is required for functions that address a specific LU
+   (i.e., ABORT TASK, CLEAR TASK SET, ABORT TASK SET, CLEAR ACA, LOGICAL
+   UNIT RESET, QUERY TASK, QUERY TASK SET, and QUERY ASYNCHRONOUS EVENT)
+   and is reserved in all others.
+
+
+
+
+
+
+
+Knight & Chadalapaka         Standards Track                   [Page 15]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+6.3.2.  Referenced Task Tag
+
+   The Reference Task Tag is 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.
+
+6.3.3.  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
+   11.6.1 of [RFC7143] when the task identified by the Referenced Task
+   Tag field is not in the task set.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Knight & Chadalapaka         Standards Track                   [Page 16]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+6.4.  Task Management Function Responses
+
+6.4.1.  Task Management Function Response PDU
+
+    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 11.6 of [RFC7143] defines the semantics used for responses to
+   SCSI task management functions.  The following responses are defined
+   in [RFC7143]:
+
+      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
+
+
+
+
+
+
+
+Knight & Chadalapaka         Standards Track                   [Page 17]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+   The Task Management Function Response PDU above and the list of task
+   management function responses above are duplicated from [RFC7143] for
+   reference only.  [RFC7143] supersedes the text in section 6.4.1 of
+   this document in the event the two documents conflict.
+
+   Responses to new task management functions (see Section 6.4.2) 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].
+
+   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.
+
+6.4.2.  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 in [SAM5].
+
+   The Task Management Function Response of "Function succeeded" MUST be
+   supported by an initiator that sends any of the new task management
+   functions (see Section 6.3).
+
+   For the QUERY TASK function, if the specified task is in the task
+   set, then the logical unit 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 logical unit 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 logical unit
+   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 logical unit returns a Response value of "Function complete".
+
+   For the I_T NEXUS RESET function, after completion of the events
+   described in Section 6.3 for this function, the logical unit returns
+   a Response value of "Function complete".  However, because the target
+   drops all connections, the Service Response (defined by [SAM5]) for
+   this SCSI task management function may not be reliably delivered to
+   the issuing initiator port.
+
+
+
+
+Knight & Chadalapaka         Standards Track                   [Page 18]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+   For the QUERY ASYNCHRONOUS EVENT, if there is a unit attention
+   condition or deferred error pending for the specified I_T_L nexus,
+   then the logical unit 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_L nexus, then the logical unit returns
+   a Response value of "Function complete".
+
+6.5.  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 included
+   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.
+
+   Sections 4.1.2 and 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.
+
+7.  Login/Text Operational Text Keys
+
+7.1.  New Operational Text Keys
+
+7.1.1.  iSCSIProtocolLevel
+
+   Use: LO, IO
+   Irrelevant when: SessionType = Discovery
+   Senders: Initiator and Target
+   Scope: SW
+
+   iSCSIProtocolLevel=<numerical-value-from-0-to-31>
+
+   Default is 1.
+   Result function is Minimum.
+
+   This key is used to negotiate the use of iSCSI features that require
+   different levels of protocol support (e.g., PDU formats, end-node
+   semantics) for proper operation.
+
+
+
+
+
+
+Knight & Chadalapaka         Standards Track                   [Page 19]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+   Negotiation of the iSCSIProtocolLevel key to a value corresponding to
+   an RFC indicates that both negotiating parties are compliant to the
+   RFC in question and agree to support the corresponding PDU formats
+   and semantics on that iSCSI session.  Features using this key are
+   expected to be cumulative.
+
+   An iSCSIProtocolLevel key negotiated to "0" indicates that the
+   implementation does not claim a specific iSCSI protocol level.
+
+   An iSCSIProtocolLevel key negotiated to "1" indicates that the
+   implementation claims compliance with [RFC7143].
+
+   An iSCSIProtocolLevel key negotiated to "2" is required to enable use
+   of features defined in this RFC.
+
+   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, and the features defined in any RFC
+   requiring a key value greater than "2", MUST NOT be used.
+
+8.  Security Considerations
+
+   Command priorities are relative values, not absolute values (see
+   [SAM5], and affect collections of commands, not necessarily
+   individual commands (see [SAM5]).  If command priority is supported,
+   it should be implemented in a fashion that avoids unwanted reduction
+   or denial of service.
+
+   All the iSCSI-related security text in [RFC3723] is directly
+   applicable to this document.  The security text in [RFC7143] is
+   directly applicable as well.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Knight & Chadalapaka         Standards Track                   [Page 20]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+9.  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 Task Management Function
+      Codes"
+
+      The following entries have been added:
+
+         9  - QUERY TASK, RFC 7144
+
+         10 - QUERY TASK SET, RFC 7144
+
+         11 - I_T NEXUS RESET, RFC 7144
+
+         12 - QUERY ASYNCHRONOUS EVENT, RFC 7144
+
+         13-127 - Unassigned
+
+   2. iSCSI Login/Text Keys
+
+      Name of the existing registry: "iSCSI Login/Text Keys"
+
+      Fields to record in the registry: Assigned value and its
+      associated RFC reference.
+
+      The following entry has been added:
+
+         iSCSIProtocolLevel,  RFC 7144
+
+   IANA has created the following iSCSI-related registries.
+
+   3.  iSCSI Protocol Level
+
+      Name of new registry: "iSCSI Protocol Level"
+
+      Namespace details: Numerical values from 0 to 31
+
+      Information that must be provided to assign a new value: An IESG-
+      approved Standards Track specification defining the semantics and
+      interoperability requirements of the proposed new value and the
+      fields to be recorded in the registry.
+
+
+
+
+Knight & Chadalapaka         Standards Track                   [Page 21]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+      Assignment policy:
+
+      The assignments of these values must be coordinated with the
+      INCITS T10 committee; therefore, review by an expert that
+      maintains an association with that committee is required prior to
+      IESG approval of the associated specification.  After creation of
+      the registry, values are to be assigned sequentially (for example,
+      any value greater than 4 will not be assigned until after the
+      value 4 has been assigned).
+
+      Special care must be taken in the assignment of new values in this
+      registry.  Compatibility and interoperability will be adversely
+      impacted if proper care is not exercised.  Features using this key
+      are expected to be cumulative.  For example, since this document
+      explicitly lists only value 2 for the features listed in this
+      document, it is expected that a new RFC assigning value 3 will
+      also have the features listed in this RFC, and therefore such an
+      RFC is expected to either revise or replace this RFC.  Assignments
+      that do not follow this policy should be reviewed and approved by
+      the INCITS T10 committee.
+
+      3-31: range available to IANA for assignment in this registry.
+
+      Fields to record in the registry: Assigned value, description, and
+      its associated RFC reference.
+
+      The following entries have been added:
+
+         Value  Description         Reference
+
+          0     No version claimed  RFC 7144
+
+          1     RFC 7143            [RFC7143]
+
+          2     RFC 7144            RFC 7144
+
+          3-31  Unassigned
+
+      Allocation Policy: Expert Review and Standards Action [RFC5226]
+
+   4.  iSCSI Task Management Function Response Codes
+
+      Name of new registry: "iSCSI Task Management Function Response
+      Codes"
+
+      Namespace details: Numerical values that can fit in 8 bits.
+
+
+
+
+
+Knight & Chadalapaka         Standards Track                   [Page 22]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+      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 available to IANA for assignment in this registry.
+
+      Fields to record in the registry: Assigned value, Operation Name,
+      and its associated RFC reference.
+
+      The following entries have been added:
+
+         0 - Function complete, [RFC7143]
+
+         1 - Task does not exist, [RFC7143]
+
+         2 - LUN does not exist, [RFC7143]
+
+         3 - Task still allegiant, [RFC7143]
+
+         4 - Task allegiance reassignment not supported, [RFC7143]
+
+         5 - Task management function not supported, [RFC7143]
+
+         6 - Function authorization failed, [RFC7143]
+
+         7 - Function succeeded, RFC 7144
+
+         8-254 - Unassigned
+
+         255 - Function rejected, [RFC7143]
+
+      Allocation Policy: Standards Action [RFC5226]
+
+
+
+
+
+
+
+
+
+
+
+
+
+Knight & Chadalapaka         Standards Track                   [Page 23]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+10.  References
+
+10.1.  Normative References
+
+   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
+              Requirement Levels", BCP 14, RFC 2119, March 1997.
+
+   [RFC3723]  Aboba, B., Tseng, J., Walker, J., Rangan, V., and F.
+              Travostino, "Securing Block Storage Protocols over IP",
+              RFC 3723, April 2004.
+
+   [RFC5048]  Chadalapaka, M., Ed., "Internet Small Computer System
+              Interface (iSCSI) Corrections and Clarifications", RFC
+              5048, October 2007.
+
+   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
+              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
+              May 2008.
+
+   [RFC7143]  Chadalapaka, M., Satran, J., Meth, K., and D. Black,
+              "Internet Small Computer System Interface (iSCSI) Protocol
+              (Consolidated)", RFC 7143, April 2014.
+
+   [SAM2]     INCITS Technical Committee T10, "SCSI Architecture Model -
+              2 (SAM-2)", ANSI INCITS 366-2003, ISO/IEC 14776-412, 2003.
+
+   [SAM5]     INCITS Technical Committee T10, "SCSI Architecture Model -
+              5 (SAM-5)", T10/BSR INCITS 515 rev 04, Committee Draft.
+
+   [SPC4]     INCITS Technical Committee T10, "SCSI Primary Commands -
+              4", ANSI INCITS 513-201x.
+
+10.2.  Informative References
+
+   [RFC3720]  Satran, J., Meth, K., Sapuntzakis, C., Chadalapaka, M.,
+              and E. Zeidner, "Internet Small Computer Systems Interface
+              (iSCSI)", RFC 3720, April 2004.
+
+11.  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
+   authors acknowledge the contributions of the entire working group and
+   other IETF reviewers.
+
+
+
+
+
+
+Knight & Chadalapaka         Standards Track                   [Page 24]
+
+RFC 7144               iSCSI SCSI Features Update             April 2014
+
+
+   The following individuals directly contributed to identifying issues
+   and/or suggesting resolutions to the issues clarified in this
+   document: David Black, Rob Elliott.  This document benefited from all
+   of these contributions.
+
+Authors' Addresses
+
+   Frederick Knight
+   7301 Kit Creek Road
+   P.O. Box 13917
+   Research Triangle Park, NC 27709
+   USA
+
+   Phone: +1-919-476-5362
+   EMail: knight@netapp.com
+
+
+   Mallikarjun Chadalapaka
+   Microsoft
+   One Microsoft Way
+   Redmond, WA 98052
+   USA
+
+   EMail: cbm@chadalapaka.com
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Knight & Chadalapaka         Standards Track                   [Page 25]
+