draft-ietf-nfsv4-scsi-layout-03.txt   draft-ietf-nfsv4-scsi-layout-04.txt 
NFSv4 C. Hellwig NFSv4 C. Hellwig
Internet-Draft November 03, 2015 Internet-Draft November 04, 2015
Intended status: Standards Track Intended status: Standards Track
Expires: May 6, 2016 Expires: May 7, 2016
Parallel NFS (pNFS) SCSI Layout Parallel NFS (pNFS) SCSI Layout
draft-ietf-nfsv4-scsi-layout-03.txt draft-ietf-nfsv4-scsi-layout-04.txt
Abstract Abstract
The Parallel Network File System (pNFS) allows a separation between The Parallel Network File System (pNFS) allows a separation between
the metadata (onto a metadata server) and data (onto a storage the metadata (onto a metadata server) and data (onto a storage
device) for a file. The SCSI Layout Type is defined in this document device) for a file. The SCSI Layout Type is defined in this document
as an extension to pNFS to allow the use SCSI based block storage as an extension to pNFS to allow the use SCSI based block storage
devices. devices.
Status of this Memo Status of this Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 6, 2016. This Internet-Draft will expire on May 7, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions Used in This Document . . . . . . . . . . . . 4 1.1. Conventions Used in This Document . . . . . . . . . . . . 4
1.2. General Definitions . . . . . . . . . . . . . . . . . . . 4 1.2. General Definitions . . . . . . . . . . . . . . . . . . . 4
1.3. Code Components Licensing Notice . . . . . . . . . . . . . 4 1.3. Code Components Licensing Notice . . . . . . . . . . . . . 4
1.4. XDR Description . . . . . . . . . . . . . . . . . . . . . 4 1.4. XDR Description . . . . . . . . . . . . . . . . . . . . . 4
2. SCSI Layout Description . . . . . . . . . . . . . . . . . . . 6 2. SCSI Layout Description . . . . . . . . . . . . . . . . . . . 6
2.1. Background and Architecture . . . . . . . . . . . . . . . 6 2.1. Background and Architecture . . . . . . . . . . . . . . . 6
2.2. layouttype4 . . . . . . . . . . . . . . . . . . . . . . . 7 2.2. layouttype4 . . . . . . . . . . . . . . . . . . . . . . . 8
2.3. GETDEVICEINFO . . . . . . . . . . . . . . . . . . . . . . 8 2.3. GETDEVICEINFO . . . . . . . . . . . . . . . . . . . . . . 8
2.3.1. Volume Identification . . . . . . . . . . . . . . . . 8 2.3.1. Volume Identification . . . . . . . . . . . . . . . . 8
2.3.2. Volume Topology . . . . . . . . . . . . . . . . . . . 9 2.3.2. Volume Topology . . . . . . . . . . . . . . . . . . . 9
2.4. Data Structures: Extents and Extent Lists . . . . . . . . 12 2.4. Data Structures: Extents and Extent Lists . . . . . . . . 12
2.4.1. Layout Requests and Extent Lists . . . . . . . . . . . 14 2.4.1. Layout Requests and Extent Lists . . . . . . . . . . . 15
2.4.2. Layout Commits . . . . . . . . . . . . . . . . . . . . 16 2.4.2. Layout Commits . . . . . . . . . . . . . . . . . . . . 16
2.4.3. Layout Returns . . . . . . . . . . . . . . . . . . . . 16 2.4.3. Layout Returns . . . . . . . . . . . . . . . . . . . . 16
2.4.4. Client Copy-on-Write Processing . . . . . . . . . . . 17 2.4.4. Client Copy-on-Write Processing . . . . . . . . . . . 17
2.4.5. Extents are Permissions . . . . . . . . . . . . . . . 18 2.4.5. Extents are Permissions . . . . . . . . . . . . . . . 18
2.4.6. End-of-file Processing . . . . . . . . . . . . . . . . 19 2.4.6. End-of-file Processing . . . . . . . . . . . . . . . . 19
2.4.7. Layout Hints . . . . . . . . . . . . . . . . . . . . . 20 2.4.7. Layout Hints . . . . . . . . . . . . . . . . . . . . . 20
2.4.8. Client Fencing . . . . . . . . . . . . . . . . . . . . 20 2.4.8. Client Fencing . . . . . . . . . . . . . . . . . . . . 20
2.5. Crash Recovery Issues . . . . . . . . . . . . . . . . . . 22 2.5. Crash Recovery Issues . . . . . . . . . . . . . . . . . . 22
2.6. Recalling Resources: CB_RECALL_ANY . . . . . . . . . . . . 22 2.6. Recalling Resources: CB_RECALL_ANY . . . . . . . . . . . . 22
2.7. Transient and Permanent Errors . . . . . . . . . . . . . . 23 2.7. Transient and Permanent Errors . . . . . . . . . . . . . . 23
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Serial Attached SCSI (SAS). pNFS SCSI layout requires block based Serial Attached SCSI (SAS). pNFS SCSI layout requires block based
SCSI command sets, for example SCSI Block Commands ([SBC3]). While SCSI command sets, for example SCSI Block Commands ([SBC3]). While
SCSI command set for non-block based access exist these are not SCSI command set for non-block based access exist these are not
supported by the SCSI layout type, and all future references to SCSI supported by the SCSI layout type, and all future references to SCSI
storage devices will imply a block based SCSI command set. storage devices will imply a block based SCSI command set.
The Server to Storage System protocol, called the "Control Protocol", The Server to Storage System protocol, called the "Control Protocol",
is not of concern for interoperability, although it will typically be is not of concern for interoperability, although it will typically be
the same SCSI based storage protocol. the same SCSI based storage protocol.
This document is based on and updates [RFC5663] to provide a better This document is based on [RFC5663] and makes changes to the block
pNFS layout protocol for SCSI based storage devices, and functionally layout type to provide a better pNFS layout protocol for SCSI based
obsoletes [RFC6688] by providing mandatory disk access protection as storage devices. Despite these changes, [RFC5663] remains the
part of the protocol. Unlike [RFC5663] this document can make use of defining document for the existing block layout type. [RFC6688] is
SCSI protocol features and thus can provide reliable fencing by using unnecessary in the context of the SCSI layout type because the new
SCSI Persistent Reservations, and it can provide reliable and layout type provides mandatory disk access protection as part of the
layout type definition. Unlike [RFC5663], this document can make use
of SCSI protocol features and thus can provide reliable fencing by
using SCSI Persistent Reservations, and it can provide reliable and
efficient device discovery by using SCSI device identifiers instead efficient device discovery by using SCSI device identifiers instead
of having to rely on probing all devices potentially attached to a of having to rely on probing all devices potentially attached to a
client for a signature. The document also optimizes the I/O path by client for a signature. This new layout type also optimizes the I/O
reducing the size of the LAYOUTCOMMIT payload. path by reducing the size of the LAYOUTCOMMIT payload
1.1. Conventions Used in This Document 1.1. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
1.2. General Definitions 1.2. General Definitions
The following definitions are provided for the purpose of providing The following definitions are provided for the purpose of providing
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