Using Remote Invalidation With RPC-Over-RDMA Transport Protocols
draft-cel-nfsv4-reminv-design-01

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Network File System Version 4                                   C. Lever
Internet-Draft                                                    Oracle
Intended status: Informational                            August 8, 2016
Expires: February 9, 2017

    Using Remote Invalidation With RPC-Over-RDMA Transport Protocols
                    draft-cel-nfsv4-reminv-design-01

Abstract

   Remote Invalidation relieves requesters/initiators of some of the
   burden of preparing memory to be accessed remotely, thus reducing the
   latency of transactions that require the use of explicit RDMA
   operations.  This document considers how to introduce Remote
   Invalidation to RPC-over-RDMA transport protocols.

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Lever                   Expires February 9, 2017                [Page 1]
Internet-Draft    Remote Invalidation And RPC-over-RDMA      August 2016

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  General Requirements  . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Memory Management Extensions  . . . . . . . . . . . . . .   4
     2.2.  Registration Types  . . . . . . . . . . . . . . . . . . .   4
     2.3.  Selecting STags To Invalidate Remotely  . . . . . . . . .   5
     2.4.  Future Enhancements . . . . . . . . . . . . . . . . . . .   5
   3.  Remote Invalidation In Operation  . . . . . . . . . . . . . .   6
     3.1.  Determining Remote Invalidation Support Status  . . . . .   6
     3.2.  Selection Of Which STag To Invalidate Remotely  . . . . .   7
     3.3.  Backward-Direction Operation  . . . . . . . . . . . . . .   7
   4.  Protocol Elements . . . . . . . . . . . . . . . . . . . . . .   8
     4.1.  Per Protocol Version Remote Invalidation  . . . . . . . .   8
     4.2.  Per Connection Remote Invalidation  . . . . . . . . . . .   9
     4.3.  Fixed Protocol Remote Invalidation  . . . . . . . . . . .   9
     4.4.  Per RPC Remote Invalidation (Single STag) . . . . . . . .  10
     4.5.  Per RPC Remote Invalidation (Multiple STags)  . . . . . .  11
     4.6.  Inter-RPC Remote Invalidation . . . . . . . . . . . . . .  12
   5.  Recommendations . . . . . . . . . . . . . . . . . . . . . . .  12
     5.1.  General Considerations  . . . . . . . . . . . . . . . . .  13
     5.2.  Analysis And Discussion . . . . . . . . . . . . . . . . .  13
     5.3.  Example Remote Invalidation Protocol  . . . . . . . . . .  14
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  15
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  16
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  16
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  16
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  17
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Introduction

   Like other RDMA-enabled storage protocols, RPC-over-RDMA Version Two
   [I-D.cel-nfsv4-rpcrdma-version-two] employs a Read-Write transfer
   model when using explicit RDMA operations to transfer data.  This
   means an RPC-over-RDMA requester exposes regions of its memory to an
   RPC-over-RDMA responder, which then uses RDMA Read and Write
   operations to transfer bulk data payloads.

   In preparation for such a transfer, a requester asks its RNIC to
   assign a steering tag, or STag, to a region of memory containing the
   data to be moved.  At this time, access rights are granted that allow
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