RFC 3783 (rfc3783) - Page 1 of 14

Small Computer Systems Interface (SCSI) Command Ordering Considerations with iSCSI

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Network Working Group                                     M. Chadalapaka
Request for Comments: 3783                                    R. Elliott
Category: Informational                              Hewlett-Packard Co.
                                                                May 2004


                Small Computer Systems Interface (SCSI)
               Command Ordering Considerations with iSCSI

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2004).  All Rights Reserved.

Abstract

   Internet Small Computer Systems Interface (iSCSI) is a Small Computer
   Systems Interface (SCSI) transport protocol designed to run on top of
   TCP.  The iSCSI session abstraction is equivalent to the classic SCSI
   "I_T nexus", which represents the logical relationship between an
   Initiator and a Target (I and T) required in order to communicate via
   the SCSI family of protocols.  The iSCSI session provides an ordered
   command delivery from the SCSI initiator to the SCSI target.  This
   document goes into the design considerations that led to the iSCSI
   session model as it is defined today, relates the SCSI command
   ordering features defined in T10 specifications to the iSCSI
   concepts, and finally provides guidance to system designers on how
   true command ordering solutions can be built based on iSCSI.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Definitions and Acronyms . . . . . . . . . . . . . . . . . . .  3
       2.1.  Definitions. . . . . . . . . . . . . . . . . . . . . . .  3
       2.2.  Acronyms . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Overview of the iSCSI Protocol . . . . . . . . . . . . . . . .  4
       3.1.  Protocol Mapping Description . . . . . . . . . . . . . .  4
       3.2.  The I_T Nexus Model. . . . . . . . . . . . . . . . . . .  5
       3.3.  Ordered Command Delivery . . . . . . . . . . . . . . . .  6
             3.3.1.  Questions. . . . . . . . . . . . . . . . . . . .  6
             3.3.2.  The Session Guarantee. . . . . . . . . . . . . .  6
             3.3.3.  Ordering Onus. . . . . . . . . . . . . . . . . .  7
             3.3.4.  Design Intent. . . . . . . . . . . . . . . . . .  7



Chadalapaka & Elliott        Informational
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