RPC-over-RDMA Version One Implementation Experience
draft-ietf-nfsv4-rfc5666-implementation-experience-02

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Document Type Active Internet-Draft (nfsv4 WG)
Last updated 2016-04-17 (latest revision 2016-04-08)
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Network File System Version 4                                   C. Lever
Internet-Draft                                                    Oracle
Intended status: Informational                             April 8, 2016
Expires: October 10, 2016

          RPC-over-RDMA Version One Implementation Experience
         draft-ietf-nfsv4-rfc5666-implementation-experience-02

Abstract

   This document details experiences and challenges implementing the
   RPC-over-RDMA Version One protocol.  Specification changes are
   recommended to address avoidable interoperability failures.

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   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on October 10, 2016.

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   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Lever                   Expires October 10, 2016                [Page 1]
Internet-Draft     RFC 5666 Implementation Experience         April 2016

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Purpose Of This Document  . . . . . . . . . . . . . . . .   3
     1.2.  Updating RFC 5666 . . . . . . . . . . . . . . . . . . . .   3
     1.3.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   2.  RPC-Over-RDMA Essentials  . . . . . . . . . . . . . . . . . .   4
     2.1.  Arguments And Results . . . . . . . . . . . . . . . . . .   4
     2.2.  Remote Direct Memory Access . . . . . . . . . . . . . . .   5
     2.3.  Transfer Models . . . . . . . . . . . . . . . . . . . . .   6
     2.4.  Upper Layer Binding Specifications  . . . . . . . . . . .   7
     2.5.  On-The-Wire Protocol  . . . . . . . . . . . . . . . . . .   8
   3.  Specification Issues  . . . . . . . . . . . . . . . . . . . .  14
     3.1.  Extensibility Considerations  . . . . . . . . . . . . . .  14
     3.2.  XDR Clarifications  . . . . . . . . . . . . . . . . . . .  15
     3.3.  Additional XDR Issues . . . . . . . . . . . . . . . . . .  18
     3.4.  The Position Zero Read Chunk  . . . . . . . . . . . . . .  19
     3.5.  RDMA_NOMSG Call Messages  . . . . . . . . . . . . . . . .  21
     3.6.  RDMA_MSG Call with Position Zero Read Chunk . . . . . . .  22
     3.7.  Padding Inline Content After A Chunk  . . . . . . . . . .  23
     3.8.  Write Chunk XDR Roundup . . . . . . . . . . . . . . . . .  25
     3.9.  Write List Error Cases  . . . . . . . . . . . . . . . . .  27
   4.  Operational Considerations  . . . . . . . . . . . . . . . . .  30
     4.1.  Computing Request Buffer Requirements . . . . . . . . . .  30
     4.2.  Default Inline Buffer Size  . . . . . . . . . . . . . . .  31
     4.3.  When To Use Reply Chunks  . . . . . . . . . . . . . . . .  31
     4.4.  Computing Credit Values . . . . . . . . . . . . . . . . .  32
     4.5.  Race Windows  . . . . . . . . . . . . . . . . . . . . . .  33
     4.6.  Detection Of Unsupported Protocol Versions  . . . . . . .  33
   5.  Pre-requisites For NFSv4  . . . . . . . . . . . . . . . . . .  34
     5.1.  Bi-directional Operation  . . . . . . . . . . . . . . . .  34
   6.  Considerations For Upper Layer Binding Specifications . . . .  35
     6.1.  Organization Of Binding Specification Requirements  . . .  35
     6.2.  RDMA-Eligibility  . . . . . . . . . . . . . . . . . . . .  35
     6.3.  Inline Threshold Requirements . . . . . . . . . . . . . .  37
     6.4.  Violations Of Binding Rules . . . . . . . . . . . . . . .  38
     6.5.  Binding Specification Completion Assessment . . . . . . .  39
   7.  Unimplemented Protocol Features . . . . . . . . . . . . . . .  39
     7.1.  Unimplemented Features To Be Removed  . . . . . . . . . .  39
     7.2.  Unimplemented Features To Be Retained . . . . . . . . . .  41
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  43
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