Parallel NFS (pNFS) Flexible File Layout
draft-ietf-nfsv4-flex-files-12
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NFSv4 B. Halevy
Internet-Draft
Intended status: Standards Track T. Haynes
Expires: January 21, 2018 Primary Data
July 20, 2017
Parallel NFS (pNFS) Flexible File Layout
draft-ietf-nfsv4-flex-files-12.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 January 21, 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 January 21, 2018 [Page 1]
Internet-Draft Flex File Layout July 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. Difference Between a Data Server and a Storage Device . . 5
1.3. 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 . . . . 7
2.2.2. Example of using Synthetic uids/gids . . . . . . . . 8
2.3. State and Locking Models . . . . . . . . . . . . . . . . 9
2.3.1. Loosely Coupled Locking Model . . . . . . . . . . . . 9
2.3.2. Tighly Coupled Locking Model . . . . . . . . . . . . 11
3. XDR Description of the Flexible File Layout Type . . . . . . 12
3.1. Code Components Licensing Notice . . . . . . . . . . . . 13
4. Device Addressing and Discovery . . . . . . . . . . . . . . . 14
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 . . . . . . . . . . . . . 21
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 . . . . . . . . . . . . . . . . . 22
6. Striping via Sparse Mapping . . . . . . . . . . . . . . . . . 23
7. Recovering from Client I/O Errors . . . . . . . . . . . . . . 23
8. Mirroring . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8.1. Selecting a Mirror . . . . . . . . . . . . . . . . . . . 25
8.2. Writing to Mirrors . . . . . . . . . . . . . . . . . . . 25
8.2.1. Single Storage Device Updates Mirrors . . . . . . . . 25
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
9. Flexible Files Layout Type Return . . . . . . . . . . . . . . 27
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