Parallel NFS (pNFS) Flexible File Layout
draft-ietf-nfsv4-flex-files-14

Document Type Active Internet-Draft (nfsv4 WG)
Last updated 2017-09-05
Stream IETF
Intended RFC status Proposed Standard
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NFSv4                                                          B. Halevy
Internet-Draft
Intended status: Standards Track                               T. Haynes
Expires: March 9, 2018                                      Primary Data
                                                      September 05, 2017

                Parallel NFS (pNFS) Flexible File Layout
                   draft-ietf-nfsv4-flex-files-14.txt

Abstract

   The Parallel Network File System (pNFS) allows a separation between
   the metadata (onto a metadata server) and data (onto a storage
   device) for a file.  The flexible file layout type is defined in this
   document as an extension to pNFS which allows the use of storage
   devices in a fashion such that they require only a quite limited
   degree of interaction with the metadata server, using already
   existing protocols.  Client-side mirroring is also added to provide
   replication of files.

Status of This Memo

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

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   This Internet-Draft will expire on March 9, 2018.

Copyright Notice

   Copyright (c) 2017 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
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect

Halevy & Haynes           Expires March 9, 2018                 [Page 1]
Internet-Draft              Flex File Layout              September 2017

   to this document.  Code Components extracted from this document must
   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  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Definitions . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Requirements Language . . . . . . . . . . . . . . . . . .   6
   2.  Coupling of Storage Devices . . . . . . . . . . . . . . . . .   6
     2.1.  LAYOUTCOMMIT  . . . . . . . . . . . . . . . . . . . . . .   6
     2.2.  Fencing Clients from the Storage Device . . . . . . . . .   6
       2.2.1.  Implementation Notes for Synthetic uids/gids  . . . .   8
       2.2.2.  Example of using Synthetic uids/gids  . . . . . . . .   8
     2.3.  State and Locking Models  . . . . . . . . . . . . . . . .   9
       2.3.1.  Loosely Coupled Locking Model . . . . . . . . . . . .  10
       2.3.2.  Tightly Coupled Locking Model . . . . . . . . . . . .  11
   3.  XDR Description of the Flexible File Layout Type  . . . . . .  13
     3.1.  Code Components Licensing Notice  . . . . . . . . . . . .  13
   4.  Device Addressing and Discovery . . . . . . . . . . . . . . .  15
     4.1.  ff_device_addr4 . . . . . . . . . . . . . . . . . . . . .  15
     4.2.  Storage Device Multipathing . . . . . . . . . . . . . . .  16
   5.  Flexible File Layout Type . . . . . . . . . . . . . . . . . .  17
     5.1.  ff_layout4  . . . . . . . . . . . . . . . . . . . . . . .  18
       5.1.1.  Error Codes from LAYOUTGET  . . . . . . . . . . . . .  22
       5.1.2.  Client Interactions with FF_FLAGS_NO_IO_THRU_MDS  . .  22
     5.2.  Interactions Between Devices and Layouts  . . . . . . . .  22
     5.3.  Handling Version Errors . . . . . . . . . . . . . . . . .  23
   6.  Striping via Sparse Mapping . . . . . . . . . . . . . . . . .  23
   7.  Recovering from Client I/O Errors . . . . . . . . . . . . . .  24
   8.  Mirroring . . . . . . . . . . . . . . . . . . . . . . . . . .  24
     8.1.  Selecting a Mirror  . . . . . . . . . . . . . . . . . . .  25
     8.2.  Writing to Mirrors  . . . . . . . . . . . . . . . . . . .  26
       8.2.1.  Single Storage Device Updates Mirrors . . . . . . . .  26
       8.2.2.  Single Storage Device Updates Mirrors . . . . . . . .  26
       8.2.3.  Handling Write Errors . . . . . . . . . . . . . . . .  26
       8.2.4.  Handling Write COMMITs  . . . . . . . . . . . . . . .  27
     8.3.  Metadata Server Resilvering of the File . . . . . . . . .  27
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