Using Remote Invalidation With RPC-Over-RDMA Transports
draft-cel-nfsv4-reminv-design-04

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Network File System Version 4                                   C. Lever
Internet-Draft                                                    Oracle
Intended status: Informational                        September 21, 2016
Expires: March 25, 2017

        Using Remote Invalidation With RPC-Over-RDMA Transports
                    draft-cel-nfsv4-reminv-design-04

Abstract

   Remote Invalidation relieves RDMA 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 RDMA Read and
   Write operations.  This document considers how to introduce Remote
   Invalidation to RPC-over-RDMA transport protocols.

Requirements Language

   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].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on March 25, 2017.

Copyright Notice

   Copyright (c) 2016 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

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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  General Requirements  . . . . . . . . . . . . . . . . . . . .   4
   3.  Remote Invalidation In Operation  . . . . . . . . . . . . . .   6
   4.  Protocol Elements . . . . . . . . . . . . . . . . . . . . . .   8
   5.  Recommendations . . . . . . . . . . . . . . . . . . . . . . .  13
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  16
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .  17
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  18

1.  Introduction

   Like other RDMA-enabled storage protocols, RPC-over-RDMA Version One
   [I-D.ietf-nfsv4-rfc5666bis] 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 a bulk data 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
   the RNIC to access or update that memory on behalf of a remote peer.
   This act is referred to as "memory registration."  The RNIC uses this
   STag to steer data to and from the registered memory region.

   When data movement is complete, each STag is dissociated from its
   memory region.  This act is referred to as "memory invalidation."  It
   prevents further responder access to that memory region by revoking
   its remote access rights.  Invalidation should be done before RPC
   applications on the requester are allowed access to memory that was
   involved in an explicit RDMA operation.

   Remote Invalidation is a technique by which an RDMA peer can request
   that a remote RNIC invalidate an STag associated with memory on that
   remote peer [RFC5042].  An RDMA consumer requests Remote Invalidation
   by posting an RDMA Send With Invalidate Work Request in place of an
   RDMA Send Work Request.  RDMA Send With Invalidate is similar to RDMA

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