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RFC 4455

 Errata 
Proposed STD
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Definition of Managed Objects for Small Computer System Interface (SCSI) Entities

Part 1 of 4, p. 1 to 18
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Network Working Group                                  M. Hallak-Stamler
Request for Comments: 4455                    Sanrad Intelligent Storage
Category: Standards Track                                       M. Bakke
                                                     Cisco Systems, Inc.
                                                             Y. Lederman
                                                  Siliquent Technologies
                                                              M. Krueger
                                                         Hewlett-Packard
                                                           K. McCloghrie
                                                     Cisco Systems, Inc.
                                                              April 2006


            Definition of Managed Objects for Small Computer
                    System Interface (SCSI) Entities

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   This memo defines a portion of the Management Information Base (MIB),
   for use with network management protocols in the Internet community.
   In particular, it describes managed objects for Small Computer System
   Interface (SCSI) entities, independently of the interconnect
   subsystem layer.

Table of Contents

   1. The Internet-Standard Management Framework ......................3
   2. Requirements Notation ...........................................3
   3. Overview ........................................................3
      3.1. Introduction ...............................................4
      3.2. SCSI Terminology ...........................................6
           3.2.1. SCSI Application Layer ..............................6
           3.2.2. SCSI Device .........................................6
           3.2.3. SCSI Port ...........................................6
           3.2.4. SCSI Initiator Device ...............................7
           3.2.5. SCSI Initiator Port .................................7

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           3.2.6. SCSI Target Device ..................................7
           3.2.7. SCSI Target Port ....................................7
           3.2.8. Logical Units .......................................7
           3.2.9. Logical Unit Number .................................7
           3.2.10. Interconnect Subsystem .............................7
           3.2.11. Device Server ......................................8
           3.2.12. Task Manager .......................................8
           3.2.13. SCSI Instance ......................................8
      3.3. SCSI MIB Module Implementation .............................8
      3.4. Bridging and Virtualization ...............................10
      3.5. SCSI Command MIB Module ...................................11
   4. Structure of the MIB ...........................................11
      4.1. The SCSI Device Group .....................................11
      4.2. The Initiator Group .......................................11
      4.3. The Target Group ..........................................11
      4.4. The Discovery Group .......................................12
      4.5. The LUN Map Group .........................................12
      4.6. The Target Statistic Group ................................12
      4.7. The Target High Speed Statistic Group .....................12
      4.8. The LUN Map Statistics Group ..............................12
      4.9. The LUN Map Statistics High Speed Group ...................13
      4.10. The Initiator Statistics Group ...........................13
      4.11. The Initiator High Speed Statistic Group .................13
      4.12. The Discovery Statistics Group ...........................13
      4.13. The Discovery Statistics High Speed Group ................14
      4.14. The Device Statistics Group ..............................14
   5. Relationships in This MIB ......................................14
   6. Relationship to Other MIBs .....................................16
      6.1. Host Resource MIB .........................................16
      6.2. iSCSI MIB Module ..........................................16
   7. Miscellaneous Details ..........................................16
      7.1. Names and Identifiers .....................................16
      7.2. Logical Unit Number .......................................16
      7.3. Notifications .............................................16
      7.4. SCSI Domains ..............................................17
      7.5. Counters: 32 Bits and 64 Bits .............................17
      7.6. Local versus Remote Entities ..............................18
   8. Abbreviations ..................................................18
   9. Object Definitions .............................................18
   10. Object Population Example: SCSI Target and Initiator
       Devices on a pSCSI Bus ........................................76
      10.1. scsiInstance Table: ......................................77
      10.2. scsiDevice Table: ........................................77
      10.3. scsiPort Table: ..........................................77
      10.4. scsiTransport Table: .....................................77
      10.5. scsiIntrDev Table: .......................................78
      10.6. scsiInitiatorPort Table: .................................78
      10.7. scsiDscTgt Table: ........................................78

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      10.8. scsiDscLUN: ..............................................78
      10.9. scsiDscLUNIdentifier: ....................................79
      10.10. scsiAttTgtPort Table: ...................................79
      10.11. scsiTgtDev Table: .......................................79
      10.12. scsiTgtPort Table: ......................................80
      10.13. scsiLU Table: ...........................................80
      10.14. scsiLuId Table: .........................................80
      10.15. scsiLunMap Table: .......................................81
      10.16. scsiAuthorizedIntr Table: ...............................81
      10.17. scsiAttIntrPort Table: ..................................81
   11. Security Considerations .......................................81
   12. Acknowledgements ..............................................84
   13. IANA Considerations ...........................................84
   14. References ....................................................84
      14.1. Normative References .....................................84
      14.2. Informative References ...................................85

1.  The Internet-Standard Management Framework

   For a detailed overview of the documents that describe the current
   Internet-Standard Management Framework, please refer to section 7 of
   RFC 3410 [RFC3410].

   Managed objects are accessed via a virtual information store, termed
   the Management Information Base or MIB.  MIB objects are generally
   accessed through the Simple Network Management Protocol (SNMP).
   Objects in the MIB are defined using the mechanisms defined in the
   Structure of Management Information (SMI).  This memo specifies a MIB
   module that is compliant to the SMIv2, which is described in STD 58,
   RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579] and STD 58, RFC 2580
   [RFC2580].

2.  Requirements Notation

   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].

3.  Overview

   This memo defines a portion of the Management Information Base (MIB)
   for use with network management protocols in the Internet community.
   In particular, it describes a set of managed objects to configure and
   monitor Small Computer System Interface entities (SCSI entities),
   i.e., SCSI target devices and SCSI initiator devices and SCSI ports.

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   SCSI is a client-server protocol in which application clients within
   a SCSI initiator device (client) issue service requests to logical
   units contained in a SCSI target device(server).

   This MIB module is based on documents defined by the ANSI T10
   Technical Committee, specifically the SCSI Architecture Model - 2
   [SAM2] and SCSI Primary Commands - 2 [SPC2].

   The [SAM2] standard is the primary source for the SCSI architecture
   discussion in this document and the terminology used in this MIB
   module.

3.1.  Introduction

   In the late 1970s, a firm called Shugart Associates started to have
   some considerable success with a peripheral interface definition in
   what became the PC marketplace, and this interface was adopted and
   extended by an open standards committee to form the Small Computer
   Systems Interface (SCSI).  SCSI defines an 8-bit-wide multi-drop
   "bus" structure, which could interconnect a total of eight
   peripherals and computer systems.

   It is important to realize that initially SCSI standardized only the
   "physical connection", i.e., the connectors, cables, and interface
   signals.  Thus, even though a peripheral could be connected to
   multiple systems, the information that flowed across the interface
   was different in each case.  This was addressed some five years later
   by the definition of a Common Command Set, and with this definition
   in place it was possible for the first time to develop a peripheral
   with both a common interface and common operating firmware for
   connection to multiple systems.

   The physical interface of SCSI continued to be developed throughout
   the 1980s with the addition of fast (up to 10 megabytes/s) and wide
   (16 bits) variants, but the distance supported remained a maximum of
   25 meters (from one end of the bus to another), and indeed some of
   the faster variants supported much less than that distance.  The
   command set development continued, with special commands for tapes,
   printers, and even processors being added to the original disk-
   oriented set.  So successful was SCSI in the 1980s that the majority
   of the available Operating Systems incorporated support for the SCSI
   command set as standard.

   However, at the end of the 1980s the distance, speed, and number of
   devices supported by SCSI were starting to become significant
   impediments to systems design, and although the "information
   explosion" had not yet started in earnest, it was already being
   anticipated.  At the same time, the serial interface technologies

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   developed for Local Area Networks such as Ethernet, and the fibre
   optics technologies that were first deployed in telecommunications
   applications were starting to appear sufficiently rugged and low cost
   for use in peripheral interface applications.  Thus, a standards
   project was begun in 1988 to develop a new serial, fibre-optic
   interface to carry the SCSI command sets and other peripheral
   protocols.  This interface eventually became known as Fibre Channel
   (FC), and it is based on an architecture centered around an
   abstractly defined "fabric", which may be a switch or a loop
   connection.  MIB modules for various FC equipments are already in
   existence.

   In order to support the new interfaces, it was necessary to
   completely reorganize the SCSI standards and definitions.  The
   command sets were separated from the physical interface definitions,
   and a SCSI Architectural Model (SAM) was created to define the
   interaction between the various standards.  It is a key to
   understanding SAM to realize that it was first created approximately
   10 years AFTER the first SCSI products were shipped!

   The most recent development in this saga occurred in 2000 when an
   IETF Working Group was formed to address, among other things, a
   definition for transporting the SCSI command sets directly over a
   TCP/IP infrastructure.  This effort is known as iSCSI [RFC3720], and
   an iSCSI MIB module is already under development [ISCSI].

   Most of the projects are in T10, except Fibre Channel, which is
   defined by T11 and IEEE defines 1394.

   The SCSI MIB module represents the SCSI protocol layer common to all
   SCSI command sets and transports.  It does not represent the command
   sets and transports themselves.  These should appear in other MIB
   modules specific to the transport or command set.  The following
   illustration shows the relationships between the various actual and
   possible SCSI-related MIB modules.

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                     +---------------------------------+
       SCSI Command  | Higher-level MIBs, specific to  |
       Sets          | command sets, disk, tape, etc.  |
                     +---------------------------------+
       SCSI          |             SCSI MIB            |
                     +-------+---------+-------+-------+
       SCSI          | iSCSI |   FCP   |  SPI  | Other |
       Transport     |  MIB  |   MIB   |  MIB  |  MIBs |
       Protocols     |       |         |       |       |
                     +-------+---------+-------+-------+
       SCSI          |  TCP  |  Fibre  |    Other      |
       Interconnect  |  MIB  | Channel | Interconnect  |
                     |       |  MIBs   |    MIBs       |
                     +-------+---------+---------------+

   An iSCSI MIB module [ISCSI] and a Fibre Channel interconnect MIB
   module [RFC4044] are currently being developed.  No development is
   currently planned for standard command-set-specific or device-
   specific MIBs.

   The TCP-MIB [RFC4022] is already a proposed standard RFC 4022.

3.2.  SCSI Terminology

   The following sections explain some of the SCSI terminology, which is
   used later in defining the MIB module.  For the authoritative
   definitions of these terms, see SAM-2 [SAM2].

3.2.1.  SCSI Application Layer

   The protocols and procedures that implement or invoke SCSI commands
   and task management functions by using services provided by a SCSI
   transport protocol layer.

3.2.2.  SCSI Device

   A SCSI device is an entity that contains one or more SCSI ports that
   are connected to a service delivery subsystem and supports a SCSI
   application protocol.

3.2.3.  SCSI Port

   A SCSI port is a device-resident entity that connects the application
   client, device server, or task manager to the service delivery
   subsystem through which requests and responses are routed.  A SCSI
   port is synonymous with port and either a SCSI initiator port or a
   SCSI target port.

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3.2.4.  SCSI Initiator Device

   A SCSI initiator device contains application clients and SCSI
   initiator ports that originate device service and task management
   requests to be processed by a SCSI target device.  When used, this
   term refers to SCSI initiator devices or SCSI target/initiator
   devices that are using the SCSI target/initiator port as a SCSI
   initiator port.

3.2.5.  SCSI Initiator Port

   A SCSI initiator port acts as the connection between application
   clients and the service delivery subsystem through which requests and
   responses are routed.  In all cases when this term is used, it refers
   to an initiator port or a SCSI target/initiator port operating as a
   SCSI initiator port.

3.2.6.  SCSI Target Device

   A SCSI target device contains logical units and SCSI target ports
   that receive device service and task management requests for
   processing.  When used, this term refers to SCSI target devices or
   SCSI target/initiator devices that are using the SCSI
   target/initiator port as a SCSI target port.

3.2.7.  SCSI Target Port

   A SCSI target port contains a task router and acts as the connection
   between device servers and task managers and the service delivery
   subsystem through which requests and responses are routed.  When this
   term is used, it refers to a SCSI target port or a SCSI
   target/initiator port operating as a SCSI target port.

3.2.8.  Logical Units

   A logical unit is an entity residing in the SCSI target device that
   implements a device model and processes SCSI commands sent by an
   application client.

3.2.9.  Logical Unit Number

   A Logical Unit Number or LUN is a 64-bit identifier for a logical
   unit.

3.2.10.  Interconnect Subsystem

   An interconnect subsystem is one or more interconnects that appear as
   a single path for the transfer of information between SCSI devices.

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3.2.11.  Device Server

   A device server is an object within the logical unit that processes
   SCSI tasks according to the rules for task management.

3.2.12.  Task Manager

   A task manager is a server within the SCSI target device that
   processes task management functions.

3.2.13.  SCSI Instance

   A "SCSI instance" is a distinct SCSI entity within a managed system.
   Whereas most implementations will have just one SCSI instance, the
   MIB module allows for multiple (virtual) instances, such that a large
   system can be "partitioned" into multiple, distinct virtual systems.

   For example, in a host, it allows multiple vendors' implementations
   of the MIB module to co-exist under a single SNMP agent through each
   vendor's implementation being a different SCSI instance.  It also
   allows a single SNMP agent to represent multiple subsystems each of
   which has its own SCSI instance.

3.3.  SCSI MIB Module Implementation

   The SCSI MIB module is a basic building block to use in the various
   SCSI management scenarios.  This module is intended to be implemented
   in every SCSI entity in a managed system.  A SCSI entity can be a
   SCSI initiator device, SCSI target device or SCSI initiator and
   Target device.  Since SCSI (storage) networking devices may contain
   more than one SCSI entity, it is possible that more than one SCSI
   instance will reside in a single device.

   In small-scale environments, a single network management station
   (NMS) may have SNMP access to both SCSI initiator devices and SCSI
   target devices.  However, if the SCSI target devices, or virtualized
   target devices, are being provided as a service, it is more likely
   that the provider of the service owns and manages the SCSI target
   devices and that the consumer of the service owns and manages the
   SCSI initiator devices.  In this case, the service provider NMS and
   the consumer NMS may have only allowed SNMP access to the SCSI target
   devices and the SCSI initiator devices, respectively.

   The figures in this chapter describe the location of the SCSI MIB
   module implementations in the various SCSI management scenarios.  The
   locations of the SCSI SNMP agent implementing the SCSI MIB module are
   denoted with '*'.

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    +----------+                                       +---------+
    |SCSI      |          SCSI Transport               |SCSI     |
    |Initiator +---------------------------------------+Target   |
    |Device    |                                       |Device   |
    |     *    |                                       |    *    |
    +----------+                                       +---------+
          |                                                 |
          |                                                 |
          |                                                 |
          |                                                 |
          |                                                 |
          |      SNMP        +----------+     SNMP          |
          +------------------|SCSI      |-------------------+
                             |Management|
                             | (NMS)    |
                             +----------+

     Figure 1.  Single SCSI Initiator Device and
                Single SCSI Target Device

   Figure 1 describes a simple SCSI management scenario of a SCSI
   initiator device, a SCSI target device, and a management station.  In
   this scenario, there are two SNMP agents, each containing its SCSI
   instance and its respective objects.  As the SCSI target device and
   SCSI initiator device are interconnected, their target and initiator
   port objects will be complementary.

   +-----------+
   |  +--------+-+          SCSI Transport               +---------+
   |  | SCSI     |---------------------------------------+ SCSI    |
   |* | Initiator+---------------------------------------+ Target  |
   +--| Device   |          SCSI Transport               | Device  |
    | |     *    |                                       |    *    |
    | +----------+                                       +---------+
    |       |                                                 |
    |       |                                                 |
    |       |                                                 |
    |       |                                                 |
    |       |                                                 |
    |SNMP   |      SNMP        +----------+     SNMP          |
    +-------+------------------|SCSI      |-------------------+
                               |Management|
                               | (NMS)    |
                               +----------+

     Figure 2.  Multiple Hosts and a Single Target Device

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   Figure 2 adds another SCSI initiator device, to the SCSI network,
   which connects to the same SCSI target device.  The additional SCSI
   initiator device also has an SNMP agent implementing the SCSI MIB
   module.  In this case, the SCSI target device's MIB module will show
   that two SCSI initiator devices are attached to it.

   +-----------+                                          +----------+
   |  +----------+              +---------------+       +-+-------+  |
   |  |SCSI      |--------------| Virtualization|       | SCSI    |  |
   |* |Initiator +--------------| Device        +-------+ Target  |  |
   +--|Device    | SCSI         |               |       | Device  | *|
    | |     *    |              |            *  |       |    *    |--+
    | +----------+ Transport    +------------+--+       +---------+ |
    |       |                                |              |       |
    |       |                                |              |       |
    |       |                                |              |       |
    |       |                                |              |       |
    |       |                                |              |       |
    |       |      SNMP        +-----------+ |   SNMP       |       |
    +-------+------------------+ SCSI      + +-+------------+-------+
                               | Management|
                               | (NMS)     |
                               +-----------+

     Figure 3.  Multiple Hosts, Virtualization Device and Multiple SCSI
                Target Devices

   Figure 3 adds an in-band virtualization device that encapsulates, and
   possibly modifies, the SCSI target devices' representation to the
   SCSI Initiator devices.  It is common practice for an in-band
   virtualization device to include both SCSI target and initiator
   device functionality.  Therefore, its SCSI MIB module implementation
   includes both the SCSI Target device and Initiator device objects.
   It should be noted that the Virtualization device might implement
   additional proprietary MIB modules, as the SCSI MIB module does not
   distinguish between physical and virtual SCSI entities.

3.4.  Bridging and Virtualization

   Storage virtualization is a concept that abstracts storage resources
   in such a way that, storage entities are provided as pool of logical
   entities.

   Usually, the virtualization process is transparent to the storage
   users (i.e., hosts).  Virtualization normally affects the SCSI
   entities represented to SCSI initiator devices.  However, the SCSI
   MIB module enables the representation of SCSI entities and their
   respective status, including error and performance-monitoring

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   statistics.  It should be possible to perform a limited number of
   configuration modification and diagnostic actions.

   The SCSI entities embodied in the bridging and virtualization devices
   can be represented by the SCSI MIB module.  However, the
   configuration of bridging and virtualization devices is beyond the
   above-described scope and therefore should be provided through other
   MIB modules.

3.5.  SCSI Command MIB Module

   The management of SCSI commands is beyond the scope of this MIB
   module.  Future SCSI Command MIB module can link to this MIB module,
   through the use of Object Identifiers (OIDs) or INDEX values of
   appropriate tables.

4.  Structure of the MIB

   This MIB module contains fourteen conformance groups:

4.1.  The SCSI Device Group

   The scsiDeviceGroup group contains the objects general to each SCSI
   instance: instance, device, and port objects.  It contains also the
   objects referring to the transport(s) used by those SCSI instances.
   This group is mandatory for all SCSI managed system.

   Alias objects are provided for SCSI instances and SCSI devices to
   enable administrators to identify them.  These objects contain
   human-readable administrative text strings, and hence use the
   SnmpAdminString textual convention from [RFC3411].

4.2.  The Initiator Group

   The scsiInitiatorDeviceGroup contains all the managed information
   related to a local SCSI initiator device and port.  In addition, it
   contains the managed objects referring to the monitored attached SCSI
   target devices.  Any managed system acting as a SCSI initiator or
   target/initiator device and port MUST support this group.

4.3.  The Target Group

   The scsiTargetDeviceGroup contains all the managed objects related to
   a local SCSI target device, a local SCSI target port, monitored
   attached initiator ports, logical units, and logical unit
   identifiers.

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   Managed systems acting as a SCSI target or target/initiator device
   and port must support this group.

4.4.  The Discovery Group

   The scsiDiscoveryGroup group is a collection of managed objects
   referring to remote SCSI target devices, remote SCSI target ports,
   remote logical units, and remote logical unit identifiers discovered
   by or configured to a managed system acting as a SCSI initiator
   device.

   Managed systems acting as a SCSI initiator device and port and
   supporting remote SCSI target devices or ports configuration or
   discovery should implement this group.

4.5.  The LUN Map Group

   The scsiLunMapGroup group is a collection of managed objects allowing
   mapping between SCSI target devices, logical units, and logical unit
   numbers in one side to remote authorized SCSI initiator devices or
   ports in another side.

   Managed systems supporting this mapping should implement the
   scsiLunMapGroup.

4.6.  The Target Statistic Group

   The scsiTargetDevStatsGroup group is a collection of managed objects
   representing various statistics referring to a SCSI target device or
   port.  Managed systems acting as a SCSI target device and port
   supporting statistics should implement this group.

4.7.  The Target High Speed Statistic Group

   The scsiTargetDevHSStatsGroup group is a collection of managed
   objects representing various statistics referring to a SCSI target
   device or port.  It provides support for systems that can quickly
   generate countable information because they run at high speed.

   Managed systems acting as a SCSI target device and port and running
   at high speed supporting should implement this group.

4.8.  The LUN Map Statistics Group

   The scsiLunMapStatsGroup group is a collection of managed objects
   representing various statistics referring to remote authorized SCSI
   initiator devices or ports.

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   Managed systems acting as a SCSI target device and port and able to
   gather statistics on remote SCSI initiator devices or ports should
   implement this group.

4.9.  The LUN Map Statistics High Speed Group

   The scsiLunMapHSStatsGroup group is a collection of managed objects
   representing various statistics referring to remote authorized SSCI
   initiator devices or ports.  It provides support for systems that can
   quickly generate countable information because they run at high
   speed.

   Managed systems acting as a SCSI target device and port and able to
   gather statistics on remote SCSI initiator devices or ports and
   running at high speed should implement this group.

4.10.  The Initiator Statistics Group

   The scsiInitiatorDevStatsGroup group is a collection of managed
   objects representing various statistics referring to a SCSI initiator
   device or port.

   Managed systems acting as a SCSI initiator device and port supporting
   statistics should implement this group.

4.11.  The Initiator High Speed Statistic Group

   The scsiInitiatorDevHSStatsGroup group is a collection of managed
   objects representing various statistics referring to a SCSI initiator
   device or port.  It provides support for systems that can quickly
   generate countable information because they run at high speed.

   Managed systems acting as a SCSI initiator device and port and
   running at high speed supporting should implement this group.

4.12.  The Discovery Statistics Group

   The scsiDiscoveryStatsGroup group is a collection of managed objects
   representing various statistics referring to remote discovered or
   configured SCSI target devices or ports.

   Managed systems acting as a SCSI initiator device and port and able
   to gather statistics on remote SCSI target devices or ports should
   implement this group.

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4.13.  The Discovery Statistics High Speed Group

   The scsiDiscoveryHSStatsGroup group is a collection of managed
   objects representing various statistics referring to remote
   discovered or configured SCSI target devices or ports.  It provides
   support for systems that can quickly generate countable information
   because they run at high speed.

   Managed systems acting as a SCSI initiator device and port and able
   to gather statistics on remote SCSI target devices or ports and
   running at high speed should implement this group.

4.14.  The Device Statistics Group

   The scsiDeviceStatGroup group is a collection of managed objects
   representing various statistics referring to a SCSI device.

   Managed systems able to gather device statistics should implement
   this group.

5.  Relationships in This MIB

   This section outlines the functionality and the dependency between
   the MIB tables providing the required management functionality for
   SCSI initiator and target devices.  For specific usage of these
   tables, the reader should refer to the description of the tables and
   their respective table entries and attributes.

   Following is a list of required SCSI initiator-related features, and
   the respective tables facilitating this functionality:

   o  List all the SCSI initiator ports that should be managed through
      this MIB module.  The table scsiIntrPortTable maintains all the
      SCSI initiator ports for the SCSI initiator devices in the MIB
      module.

   o  Provide a list of all SCSI target ports or SCSI target devices to
      which a SCSI initiator port can attach.  This should prevent a
      SCSI initiator device or port from attaching to SCSI target
      devices that should be either invisible or inaccessible to it.
      The entries in this list can be created either manually or by
      automatic discovery mechanisms (e.g., SLP, iSNS).  The
      ScsiDscTgtTable provides this information.  The entries in this
      table point to the SCSI initiator port, and indicate that the SCSI
      initiator port can only attach to SCSI target ports or SCSI target
      devices provided in the respective entries of the ScsiDscTgtTable.

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      This MIB module permits, but does not require, this table to be
      written via SNMP.  There are significant security considerations
      in allowing writes to this table; see Section 11.

   o  The information, for the aforementioned SCSI target ports or SCSI
      target devices, about the LUs and their respective LUN Ids should
      be provided.  The scsiDscLunTable and scsiDscLunIdTable maintain
      this information.

   o  The scsiAttTgtPortTable provides the information about the SCSI
      target ports each SCSI initiator port is currently communicating
      with.  This table should be dynamically updated to reflect those
      connections.

   Following is a list of required SCSI target device-related features,
   and the respective tables facilitating this functionality:

   o  List all the SCSI target ports that should be managed through this
      MIB module.  The table scsiTgtPortTable maintains all the SCSI
      target ports for the SCSI target devices in the MIB module.

   o  Provide a list of valid SCSI initiator ports or SCSI initiator
      devices authorized to attach to a SCSI target port.  This list
      should feature the concept of "access lists", which are common in
      IP routers and switches.  The ScsiAuthorizedIntr table provides
      this information.  This MIB module permits, but does not require
      this table to be written via SNMP.  There are significant security
      considerations in allowing writes to this table; see Section 11.

   o  It should be possible to specify the list of LUNs exposed to each
      SCSI initiator port or device, when it is attached to the SCSI
      target device.  SCSI target devices must provide a default list of
      LUNs.  This list of LUNs can either be a unique list for each SCSI
      initiator device or be the default list.  For each entry in the
      ScsiAuthorizedIntr table, a pointer, named
      scsiAuthIntrLunMapIndex, indexing the ScsiLunMapTable facilitates
      this feature.

   o  Provide means to monitor all the SCSI initiator ports currently
      attached to this SCSI target port.  The scsiAttIntrPortTable
      provides this information.  This table should be dynamically
      updated to reflect those connections.

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6.  Relationship to Other MIBs

6.1.  Host Resource MIB

   The SCSI MIB module extends objects defined in the host resource MIB
   module to SCSI-specific entities but does not contain information on
   software modules such as device drivers.  If MIB objects are required
   for installed packages of SCSI software, then the hrSWInstalledGroup
   of the Host Resources MIB [RFC2790] are the standard MIB objects to
   use.

6.2.  iSCSI MIB Module

   The SCSI MIB module defines managed objects for the SCSI protocol
   layer.  The SCSI layer can run on top of several transport layers;
   iSCSI is one of them.  The ISCSI-MIB [ISCSI] is the MIB portion
   defining the managed objects for the transport called iSCSI.  In the
   same way, a fibre channel or parallel SCSI MIB module would define
   managed objects for a transport called, respectively, fibre channel
   or parallel SCSI.

   The relationship between the SCSI MIB module and any valid transport
   MIB module is determined via the SCSI port managed table that has an
   object pointing to the corresponding row, if any, of the relevant
   table in a transport MIB module.

7.  Miscellaneous Details

7.1.  Names and Identifiers

   The names and the identifiers of the SCSI devices, ports, and logical
   units depend on the underlying transport protocols; their format and
   length vary accordingly.  Please refer to SAM-2 [SAM2] for more
   details.

7.2.  Logical Unit Number

   The Logical Unit Number is a 64-bit integer.  This type does not
   exist in SMI and therefore, this MIB contains a textual convention
   defining LUN as an OCTET STRING.

7.3.  Notifications

   Separate SNMP notifications may be enabled/disabled to notify of a
   change in any of the SCSI device status variables.  A notification
   will be generated theoretically for each occurrence (see restriction

Top      ToC       Page 17 
   below) of the abnormal status (e.g., if the SCSI device's current
   status is abnormal and another logical unit changes its status from
   available to abnormal another notification will occur).

   To avoid sending an excessive number of notifications due to multiple
   errors counted, an SNMP agent implementing the SCSI MIB module should
   not send more than three SCSI notifications in any 10-second period.

   The 3-in-10 rule was chosen because one notification every three
   seconds was deemed often enough, but if and when two or three
   different notifications happen at the same time, it would not be
   desirable to suppress them.  Three notifications in 10 seconds is a
   happy medium, where a short burst of notifications is allowed,
   without inundating the network and/or destination host with a large
   number of notifications.

   The ultimate control on sending of notifications is in command of the
   notification generator module specified in [RFC3413].

7.4.  SCSI Domains

   SAM-2 [SAM2] specifies that devices belong to a domain.  However, it
   is not usually possible to determine this from within a system, so
   domains are not represented within this MIB module.

7.5.  Counters: 32 Bits and 64 Bits

   Some counters, in (newer) high-performance systems, can increase at a
   fast enough rate such that their representation as Counter32s can
   cause them to "wrap" in less than an hour.  The SMIv2 provides
   Counter64 as the syntax for such counters.  However, (older) SNMPv1
   implementations cannot support Counter64s.  Thus, this MIB module
   defines such counters as both Counter32s and Counter64's.

   The counters in this MIB module that count data are defined in terms
   of megabytes (i.e., as the number of megabytes of data), such that
   Counter64s are not required.

   However, the counters in this MIB module that count commands, when in
   use at 5 GBit/second with 512-byte read/write operations, could wrap
   within an hour.  Therefore, each of these counters will be defined as
   both a Counter32 and a Counter64, with the latter being mandatory,
   for system speeds of 4 Gbit/second or higher.

   A possible (but not required) implementation strategy is to have the
   value of each Counter32 be the same value as the low-order 32 bits of
   the corresponding Counter64.

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7.6.  Local versus Remote Entities

   This MIB module qualifies often SCSI entities as local or remote.
   The local entities are the ones for which the agent is reporting.
   The remote entities are the ones that the local entities are in
   communication with via the SCSI protocol.

8.  Abbreviations

   This MIB module will use the following abbreviations:

      Inst = Instance

      Dev = SCSI Device

      Tgt = SCSI Target Device

      Intr = SCSI Initiator Device

      Att = Attached

      Id = Identifier

      Dsc = Discovered

      pSCSI = Parallel SCSI



(page 18 continued on part 2)

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