draft-ietf-nfsv4-pnfs-block-05.txt   draft-ietf-nfsv4-pnfs-block-06.txt 
NFSv4 Working Group David L. Black NFSv4 Working Group David L. Black
Internet Draft Stephen Fridella Internet Draft Stephen Fridella
Expires: May 21, 2008 Jason Glasgow Expires: August 25, 2008 Jason Glasgow
Intended Status: Proposed Standard EMC Corporation Intended Status: Proposed Standard EMC Corporation
November 18, 2007 February 25, 2008
pNFS Block/Volume Layout pNFS Block/Volume Layout
draft-ietf-nfsv4-pnfs-block-05.txt draft-ietf-nfsv4-pnfs-block-06.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that By submitting this Internet-Draft, each author represents that
any applicable patent or other IPR claims of which he or she is any applicable patent or other IPR claims of which he or she is
aware have been or will be disclosed, and any of which he or she aware have been or will be disclosed, and any of which he or she
becomes aware will be disclosed, in accordance with Section 6 of becomes aware will be disclosed, in accordance with Section 6 of
BCP 79. BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
skipping to change at page 2, line 17 skipping to change at page 2, line 17
Conventions used in this document 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 RFC-2119 [RFC2119]. document are to be interpreted as described in RFC-2119 [RFC2119].
Table of Contents Table of Contents
1. Introduction...................................................3 1. Introduction...................................................3
1.1. General Definitions.......................................3 1.1. General Definitions.......................................3
2. Block Layout Description.......................................4 1.2. XDR Description of NFSv4.1 block layout...................4
2.1. Background and Architecture...............................4 2. Block Layout Description.......................................5
2.2. GETDEVICELIST and GETDEVICEINFO...........................5 2.1. Background and Architecture...............................5
2.2.1. Volume Identification................................5 2.2. GETDEVICELIST and GETDEVICEINFO...........................6
2.2.2. Volume Topology......................................6 2.2.1. Volume Identification................................6
2.2.2. Volume Topology......................................7
2.2.3. GETDEVICELIST and GETDEVICEINFO deviceid4............9 2.2.3. GETDEVICELIST and GETDEVICEINFO deviceid4............9
2.3. Data Structures: Extents and Extent Lists.................9 2.3. Data Structures: Extents and Extent Lists................10
2.3.1. Layout Requests and Extent Lists....................12 2.3.1. Layout Requests and Extent Lists....................12
2.3.2. Layout Commits......................................13 2.3.2. Layout Commits......................................13
2.3.3. Layout Returns......................................13 2.3.3. Layout Returns......................................14
2.3.4. Client Copy-on-Write Processing.....................14 2.3.4. Client Copy-on-Write Processing.....................14
2.3.5. Extents are Permissions.............................15 2.3.5. Extents are Permissions.............................16
2.3.6. End-of-file Processing..............................17 2.3.6. End-of-file Processing..............................17
2.3.7. Layout Hints........................................17 2.3.7. Layout Hints........................................18
2.3.8. Client Fencing......................................18 2.3.8. Client Fencing......................................18
2.4. Crash Recovery Issues....................................20 2.4. Crash Recovery Issues....................................20
2.5. Recalling resources: CB_RECALL_ANY.......................20 2.5. Recalling resources: CB_RECALL_ANY.......................21
2.6. Transient and Permanent Errors...........................21 2.6. Transient and Permanent Errors...........................21
3. Security Considerations.......................................21 3. Security Considerations.......................................22
4. Conclusions...................................................23 4. Conclusions...................................................23
5. IANA Considerations...........................................23 5. IANA Considerations...........................................23
6. Acknowledgments...............................................23 6. Acknowledgments...............................................23
7. References....................................................23 7. References....................................................24
7.1. Normative References.....................................23 7.1. Normative References.....................................24
7.2. Informative References...................................24 7.2. Informative References...................................24
Author's Addresses...............................................24 Authors' Addresses...............................................24
Intellectual Property Statement..................................25 Intellectual Property Statement..................................25
Disclaimer of Validity...........................................25 Disclaimer of Validity...........................................25
Copyright Statement..............................................25 Copyright Statement..............................................26
Acknowledgment...................................................25 Acknowledgment...................................................26
1. Introduction 1. Introduction
Figure 1 shows the overall architecture of a pNFS system: Figure 1 shows the overall architecture of a pNFS system:
+-----------+ +-----------+
|+-----------+ +-----------+ |+-----------+ +-----------+
||+-----------+ | | ||+-----------+ | |
||| | NFSv4.1 + pNFS | | ||| | NFSv4.1 + pNFS | |
+|| Clients |<------------------------------>| Server | +|| Clients |<------------------------------>| Server |
skipping to change at page 4, line 19 skipping to change at page 4, line 19
logic to access the NFS server directly. The client may also be logic to access the NFS server directly. The client may also be
the traditional operating system client that provides remote file the traditional operating system client that provides remote file
system services for a set of applications. system services for a set of applications.
Server Server
The "Server" is the entity responsible for coordinating client The "Server" is the entity responsible for coordinating client
access to a set of file systems and is identified by a Server access to a set of file systems and is identified by a Server
owner. owner.
1.2. XDR Description
This document contains the XDR ([XDR]) description of the NFSv4.1
block layout protocol. The XDR description is embeded in this
document in a way that makes it simple for the reader to extract into
ready to compile form. The reader can feed this document into the
following shell script to produce the machine readable XDR
description of the NFSv4.1 block layout:
#!/bin/sh
grep "^ *///" | sed 's?^ *///??'
I.e. if the above script is stored in a file called "extract.sh", and
this document is in a file called "spec.txt", then the reader can do:
sh extract.sh < spec.txt > nfs4_block_layout_spec.x
The effect of the script is to remove both leading white space and a
sentinel sequence of "///" from each matching line.
The XDR header description, with the sentinel sequence follows, with
additional pieces throughout the document:
////*
/// * This file was machine generated for
/// * draft-ietf-nfsv4-pnfs-block-06
/// * Last updated Tue Jan 29 02:57:06 CST 2008
/// */
////*
/// * Copyright (C) The IETF Trust (2007-2008)
/// * All Rights Reserved.
/// *
/// * Copyright (C) The Internet Society (1998-2006).
/// * All Rights Reserved.
/// */
///
////*
/// * nfs4_block_layout_prot.x
/// */
///
///%#include "nfsv41.h"
///
2. Block Layout Description 2. Block Layout Description
2.1. Background and Architecture 2.1. Background and Architecture
The fundamental storage abstraction supported by block/volume storage The fundamental storage abstraction supported by block/volume storage
is a storage volume consisting of a sequential series of fixed size is a storage volume consisting of a sequential series of fixed size
blocks. This can be thought of as a logical disk; it may be realized blocks. This can be thought of as a logical disk; it may be realized
by the Storage System as a physical disk, a portion of a physical by the Storage System as a physical disk, a portion of a physical
disk or something more complex (e.g., concatenation, striping, RAID, disk or something more complex (e.g., concatenation, striping, RAID,
and combinations thereof) involving multiple physical disks or and combinations thereof) involving multiple physical disks or
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2.2. GETDEVICELIST and GETDEVICEINFO 2.2. GETDEVICELIST and GETDEVICEINFO
2.2.1. Volume Identification 2.2.1. Volume Identification
Storage Systems such as storage arrays can have multiple physical Storage Systems such as storage arrays can have multiple physical
network ports that need not be connected to a common network, network ports that need not be connected to a common network,
resulting in a pNFS client having simultaneous multipath access to resulting in a pNFS client having simultaneous multipath access to
the same storage volumes via different ports on different networks. the same storage volumes via different ports on different networks.
The networks may not even be the same technology - for example, The networks may not even be the same technology - for example,
access to the same volume via both iSCSI and Fibre Channel is access to the same volume via both iSCSI and Fibre Channel is
possible, hence network address are difficult to use for volume possible, hence network addresses are difficult to use for volume
identification. For this reason, this pNFS block layout identifies identification. For this reason, this pNFS block layout identifies
storage volumes by content, for example providing the means to match storage volumes by content, for example providing the means to match
(unique portions of) labels used by volume managers. Any block pNFS (unique portions of) labels used by volume managers. Any block pNFS
system using this layout MUST support a means of content-based unique system using this layout MUST support a means of content-based unique
volume identification that can be employed via the data structure volume identification that can be employed via the data structure
given here. given here.
struct pnfs_block_sig_component4 { /* disk signature component */ ///struct pnfs_block_sig_component4 { /* disk signature component */
/// int64_t sig_offset; /* byte offset of component
int64_t sig_offset; /* byte offset of component on /// on volume*/
volume*/ /// opaque contents<>; /* contents of this component
/// of the signature */
opaque contents<>; /* contents of this component of ///};
the signature (this is ///
opaque) */
};
Note that the opaque "contents" field in the Note that the opaque "contents" field in the
"pnfs_block_sig_component4" structure MUST NOT be interpreted as a "pnfs_block_sig_component4" structure MUST NOT be interpreted as a
zero-terminated string, as it may contain embedded zero-valued bytes. zero-terminated string, as it may contain embedded zero-valued bytes.
There are no restrictions on alignment (e.g., neither sig_offset nor There are no restrictions on alignment (e.g., neither sig_offset nor
the length are required to be multiples of 4). The sig_offset is a the length are required to be multiples of 4). The sig_offset is a
signed quantity which when positive represents an byte offset from signed quantity which when positive represents an byte offset from
the start of the volume, and when negative represents an byte offset the start of the volume, and when negative represents an byte offset
from the end of the volume. from the end of the volume.
Negative offsets are permitted in order to simplify the client Negative offsets are permitted in order to simplify the client
implementation on systems where the device label is found at a fixed implementation on systems where the device label is found at a fixed
offset from the end of the volume. If the server uses negative offset from the end of the volume. If the server uses negative
offsets to describe the signature, then the client and server MUST offsets to describe the signature, then the client and server MUST
NOT see different volume sizes. Negative offsets SHOULD NOT be used NOT see different volume sizes. Negative offsets SHOULD NOT be used
in systems that dynamically resize volumes unless care is taken to in systems that dynamically resize volumes unless care is taken to
ensure that the device label is always present at the offset from the ensure that the device label is always present at the offset from the
end of the volume as seen by the clients. end of the volume as seen by the clients.
A signature is an array up to "PNFS_BLOCK_MAX_SIG_COMP" (defined A signature is an array of up to "PNFS_BLOCK_MAX_SIG_COMP" (defined
below) signature components. The client MUST NOT assume that all below) signature components. The client MUST NOT assume that all
signature components are colocated within a single sector on a block signature components are colocated within a single sector on a block
device. device.
The pNFS client block layout driver uses this volume identification The pNFS client block layout driver uses this volume identification
to map pnfs_block_volume_type4 PNFS_BLOCK_VOLUME_SIMPLE deviceid4s to to map pnfs_block_volume_type4 PNFS_BLOCK_VOLUME_SIMPLE deviceid4s to
its local view of a LUN. its local view of a LUN.
2.2.2. Volume Topology 2.2.2. Volume Topology
The pNFS block server volume topology is expressed as an arbitrary The pNFS block server volume topology is expressed as an arbitrary
combination of base volume types enumerated in the following data combination of base volume types enumerated in the following data
structures. structures.
enum pnfs_block_volume_type4 { ///enum pnfs_block_volume_type4 {
/// PNFS_BLOCK_VOLUME_SIMPLE = 0, /* volume maps to a single
PNFS_BLOCK_VOLUME_SIMPLE = 0, /* volume maps to a single LU */ /// LU */
/// PNFS_BLOCK_VOLUME_SLICE = 1, /* volume is a slice of
PNFS_BLOCK_VOLUME_SLICE = 1, /* volume is a slice of another /// another volume */
volume */ /// PNFS_BLOCK_VOLUME_CONCAT = 2, /* volume is a
/// concatenation of
PNFS_BLOCK_VOLUME_CONCAT = 2, /* volume is a concatenation of /// multiple volumes */
multiple volumes */ /// PNFS_BLOCK_VOLUME_STRIPE = 3 /* volume is striped across
/// multiple volumes */
PNFS_BLOCK_VOLUME_STRIPE = 3 /* volume is striped across ///};
multiple volumes */ ///
///const PNFS_BLOCK_MAX_SIG_COMP = 16; /* maximum components per
}; /// signature */
///struct pnfs_block_simple_volume_info4 {
const PNFS_BLOCK_MAX_SIG_COMP = 16; /* maximum components per ///pnfs_block_sig_component4 ds<PNFS_BLOCK_MAX_SIG_COMP>;
signature */ /// /* disk signature */
///};
struct pnfs_block_simple_volume_info4 { ///
///
deviceid4 vol_id; /* this volume id */ ///struct pnfs_block_slice_volume_info4 {
pnfs_block_sig_component4 ds<PNFS_BLOCK_MAX_SIG_COMP>; /// offset4 start; /* offset of the start of the
/* disk signature */ /// slice in bytes */
/// length4 length; /* length of slice in bytes */
}; /// uint32_t volume; /* array index of sliced
/// volume */
struct pnfs_block_slice_volume_info4 { ///};
///
deviceid4 vol_id; /* this volume id */ ///struct pnfs_block_concat_volume_info4 {
/// uint32_t volumes<>; /* array index of volumes
offset4 start; /* offset of the start of the /// which are concatenated */
slice in bytes */ ///};
///
length4 length; /* length of slice in bytes */ ///struct pnfs_block_stripe_volume_info4 {
/// length4 stripe_unit; /* size of stripe in bytes */
deviceid4 volume; /* volume which is sliced */ /// uint32_t volumes<>; /* array indices of volumes
/// which are striped across --
}; /// MUST be same size */
///};
struct pnfs_block_concat_volume_info4 { ///
///union pnfs_block_volume4 switch (pnfs_block_volume_type4 type) {
deviceid4 vol_id; /* this volume id */ /// case PNFS_BLOCK_VOLUME_SIMPLE:
/// pnfs_block_simple_volume_info4 simple_info;
deviceid4 volumes<>; /* volumes which are /// case PNFS_BLOCK_VOLUME_SLICE:
concatenated */ /// pnfs_block_slice_volume_info4 slice_info;
/// case PNFS_BLOCK_VOLUME_CONCAT:
}; /// pnfs_block_concat_volume_info4 concat_info;
/// case PNFS_BLOCK_VOLUME_STRIPE:
struct pnfs_block_stripe_volume_info4 { /// pnfs_block_stripe_volume_info4 stripe_info;
///};
deviceid4 vol_id; /* this volume id */ ///
///struct pnfs_block_deviceaddr4 {
length4 stripe_unit; /* size of stripe in octects */ /// pnfs_block_volume4 volumes<>; /* array of volumes */
///};
deviceid4 volumes<>; /* volumes which are striped ///
across -- MUST be same size
*/
};
union pnfs_block_volume4 switch (pnfs_block_volume_type4 type) {
case PNFS_BLOCK_VOLUME_SIMPLE:
pnfs_block_simple_volume_info4 simple_info;
case PNFS_BLOCK_VOLUME_SLICE:
pnfs_block_slice_volume_info4 slice_info;
case PNFS_BLOCK_VOLUME_CONCAT:
pnfs_block_concat_volume_info4 concat_info;
case PNFS_BLOCK_VOLUME_STRIPE:
pnfs_block_stripe_volume_info4 stripe_info;
};
struct pnfs_block_deviceaddr4 {
pnfs_block_volume4 volumes<>; /* array of volumes */
};
The "pnfs_block_deviceaddr4" data structure is a structure that The "pnfs_block_deviceaddr4" data structure is a structure that
allows arbitrarily complex nested volume structures to be encoded. allows arbitrarily complex nested volume structures to be encoded.
The types of aggregations that are allowed are stripes, The types of aggregations that are allowed are stripes,
concatenations, and slices. Note that the volume topology expressed concatenations, and slices. Note that the volume topology expressed
in the pnfs_block_deviceaddr4 data structure will always resolve to a in the pnfs_block_deviceaddr4 data structure will always resolve to a
set of pnfs_block_volume_type4 PNFS_BLOCK_VOLUME_SIMPLE. The array set of pnfs_block_volume_type4 PNFS_BLOCK_VOLUME_SIMPLE. The array
of volumes is ordered such that the root volume is the last element of volumes is ordered such that the root of the volume hierarchy is
of the array. Concat, slice and stripe volumes MUST refer to volumes the last element of the array. Concat, slice and stripe volumes MUST
defined by lower indexed elements of the array. refer to volumes defined by lower indexed elements of the array.
The "pnfs_block_device_addr4" data structure is returned by the The "pnfs_block_device_addr4" data structure is returned by the
server as the storage-protocol-specific opaque field da_addr_body in server as the storage-protocol-specific opaque field da_addr_body in
the "device_addr4" structure by successful GETDEVICELIST and the "device_addr4" structure by a successful GETDEVICELIST operation.
GETDEVICEINFO operations. [NFSV4.1]. Typically the server in [NFSV4.1].
response to a GETDEVICELIST request will return a single
"devlist_item4" in the gdlr_devinfo_list array. This is because the
"opaque da_addr_body" field inside the "device_addr4" encodes the
entire volume hierarchy. In the case of copy-on-write file systems,
the "gdlr_devinfo_list" array will contain two devices_item4's, one
describing the read-only volume hierarchy, and one describing the
writable volume hierarchy. There is no required ordering of the
readable and writable volumes in the array as the volumes are
uniquely identified by their deviceid4, and are referred to by
layouts using the deviceid4. Another example of the server returning
multiple device items occurs when the file handle represents the root
of a name space spanning multiple physical file systems on the
server, each with a different volume hierarchy.
As noted above, all device_addr4 structures eventually resolve to a As noted above, all device_addr4 structures eventually resolve to a
set of volumes of type PNFS_BLOCK_VOLUME_SIMPLE. These volumes are set of volumes of type PNFS_BLOCK_VOLUME_SIMPLE. These volumes are
each uniquely identified by a set of signature components. each uniquely identified by a set of signature components.
Complicated volume hierarchies may be composed of dozens of volumes Complicated volume hierarchies may be composed of dozens of volumes
each with several signature components, thus the device address may each with several signature components, thus the device address may
require several kilobytes. The client SHOULD be prepared to allocate require several kilobytes. The client SHOULD be prepared to allocate
a large buffer to contain the result, and in the case of the server a large buffer to contain the result. In the case of the server
returning NFS4ERR_TOOSMALL the client SHOULD be prepared to allocate returning NFS4ERR_TOOSMALL the client SHOULD allocate a buffer of at
a large enough buffer to contain the expected result. least gdir_mincount_bytes to contain the expected result and retry
the GETDEVICEINFO request.
2.2.3. GETDEVICELIST and GETDEVICEINFO deviceid4 2.2.3. GETDEVICELIST and GETDEVICEINFO deviceid4
The "deviceid4 dli_id" returned in the devlist_item4 of a successful The server in response to a GETDEVICELIST request typically will
GETDEVICELIST operation is a shorthand id used to reference the whole return a single "deviceid4" in the gdlr_deviceid_list array. This is
volume topology. Decoding the "pnfs_block_deviceaddr4" results in a because the deviceid4 when passed to GETDEVICEINFO will return a
flat ordering of data blocks mapped to PNFS_BLOCK_VOLUME_SIMPLE "device_addr4" which encodes the entire volume hierarchy. In the
deviceid4s. Combined with the deviceid4 mapping to a client LUN case of copy-on-write file systems, the "gdlr_deviceid_list" array
described in 2.2.1 Volume Identification, a logical volume offset can may contain two deviceid4's, one referencing the read-only volume
be mapped to a block on a pNFS client LUN. [NFSV4.1] With the hierarchy, and one referencing the writable volume hierarchy. There
exception of the root volume id, the device ids returned in the is no required ordering of the readable and writable ids in the array
volumes array of a pnfs_block_deviceaddr4 data structure should not as the volumes are uniquely identified by their deviceid4, and are
be passed as arguments in a GETDEVICEINFO request. These non-root referred to by layouts using the deviceid4. Another example of the
volume device ids are never returned by LAYOUTGET in the server returning multiple device items occurs when the file handle
"pnfs_block_layout4 vol_id" field. If a non-root device id is passed represents the root of a name space spanning multiple physical file
as an argument in a GETDEVICEINFO request, the server SHOULD return systems on the server, each with a different volume hierarchy. In
NFS4ERR_INVAL. this example a server implementation may return either a list of
deviceids used by each of the physical file systems, or it may return
an empty list.
Each deviceid4 returned by a successful GETDEVICELIST operation is a
shorthand id used to reference the whole volume topology. These
device ids, as well as device ids return in extents of a LAYOUTGET
operation, can be used as input to the GETDEVICEINFO operation.
Decoding the "pnfs_block_deviceaddr4" results in a flat ordering of
data blocks mapped to PNFS_BLOCK_VOLUME_SIMPLE volumes. Combined
with the mapping to a client LUN described in 2.2.1 Volume
Identification, a logical volume offset can be mapped to a block on a
pNFS client LUN. [NFSV4.1]
2.3. Data Structures: Extents and Extent Lists 2.3. Data Structures: Extents and Extent Lists
A pNFS block layout is a list of extents within a flat array of data A pNFS block layout is a list of extents within a flat array of data
blocks in a logical volume. The details of the volume topology can blocks in a logical volume. The details of the volume topology can
be determined by using the GETDEVICEINFO or GETDEVICELIST operation be determined by using the GETDEVICEINFO operation (see discussion of
(see discussion of volume identification, section 2.2 above). The volume identification, section 2.2 above). The block layout
block layout describes the individual block extents on the volume describes the individual block extents on the volume that make up the
that make up the file. The offsets and length contained in an extent file. The offsets and length contained in an extent are specified in
are specified in units of bytes. units of bytes.
enum pnfs_block_extent_state4 {
PNFS_BLOCK_READWRITE_DATA = 0, /* the data located by this
extent is valid
for reading and writing. */
PNFS_BLOCK_READ_DATA = 1, /* the data located by this
extent is valid for reading
only; it may not be written.
*/
PNFS_BLOCK_INVALID_DATA = 2, /* the location is valid; the
data is invalid. It is a
newly (pre-) allocated
extent. There is physical
space on the volume. */
PNFS_BLOCK_NONE_DATA = 3 /* the location is invalid. It
is a hole in the file. There
is no physical space on the
volume. */
};
struct pnfs_block_extent4 {
deviceid4 vol_id; /* id of logical volume on which
extent of file is stored. */
offset4 file_offset; /* the starting byte offset in
the file */
length4 extent_length; /* the size in bytes of the
extent */
offset4 storage_offset; /* the starting byte offset in
the volume */
pnfs_block_extent_state4 es; /* the state of this extent */
};
struct pnfs_block_layout4 {
pnfs_block_extent4 extents<>; /* extents which make up this
layout. */
}; ///enum pnfs_block_extent_state4 {
/// PNFS_BLOCK_READWRITE_DATA = 0, /* the data located by this
/// extent is valid
/// for reading and writing. */
/// PNFS_BLOCK_READ_DATA = 1, /* the data located by this
/// extent is valid for reading
/// only; it may not be
/// written. */
/// PNFS_BLOCK_INVALID_DATA = 2, /* the location is valid; the
/// data is invalid. It is a
/// newly (pre-) allocated
/// extent. There is physical
/// space on the volume. */
/// PNFS_BLOCK_NONE_DATA = 3 /* the location is invalid. It
/// is a hole in the file.
/// There is no physical space
/// on the volume. */
///};
///
///struct pnfs_block_extent4 {
/// deviceid4 vol_id; /* id of logical volume on
/// which extent of file is
/// stored. */
/// offset4 file_offset; /* the starting byte offset in
/// the file */
/// length4 extent_length; /* the size in bytes of the
/// extent */
/// offset4 storage_offset; /* the starting byte offset in
/// the volume */
/// pnfs_block_extent_state4 es; /* the state of this extent */
///};
///
///struct pnfs_block_layout4 {
/// pnfs_block_extent4 extents<>; /* extents which make up this
/// layout. */
///};
///
The block layout consists of a list of extents which map the logical The block layout consists of a list of extents which map the logical
regions of the file to physical locations on a volume. The "storage regions of the file to physical locations on a volume. The "storage
offset" field within each extent identifies a location on the logical offset" field within each extent identifies a location on the logical
volume specified by the "vol_id" field in the extent. The vol_id volume specified by the "vol_id" field in the extent. The vol_id
itself is shorthand for the whole topology of the logical volume on itself is shorthand for the whole topology of the logical volume on
which the file is stored. The client is responsible for translating which the file is stored. The client is responsible for translating
this logical offset into an offset on the appropriate underlying SAN this logical offset into an offset on the appropriate underlying SAN
logical unit. In most cases all extents in a layout will reside on logical unit. In most cases all extents in a layout will reside on
the same volume and thus have the same vol_id. In the case of copy the same volume and thus have the same vol_id. In the case of copy
on write file systems, the PNFS_BLOCK_READ_DATA extents may have a on write file systems, the PNFS_BLOCK_READ_DATA extents may have a
different vol_id from the writable extents. different vol_id from the writable extents.
Each extent maps a logical region of the file onto a portion of the Each extent maps a logical region of the file onto a portion of the
specified logical volume. The file_offset, extent_length, and es specified logical volume. The file_offset, extent_length, and es
fields for an extent returned from the server are always valid. The fields for an extent returned from the server are valid for all
interpretation of the storage_offset field depends on the value of es extents. In contrast, the interpretation of the storage_offset field
as follows (in increasing order): depends on the value of es as follows (in increasing order):
o PNFS_BLOCK_READ_WRITE_DATA means that storage_offset is valid, and o PNFS_BLOCK_READ_WRITE_DATA means that storage_offset is valid, and
points to valid/initialized data that can be read and written. points to valid/initialized data that can be read and written.
o PNFS_BLOCK_READ_DATA means that storage_offset is valid and points o PNFS_BLOCK_READ_DATA means that storage_offset is valid and points
to valid/ initialized data which can only be read. Write to valid/ initialized data which can only be read. Write
operations are prohibited; the client may need to request a read- operations are prohibited; the client may need to request a read-
write layout. write layout.
o PNFS_BLOCK_INVALID_DATA means that storage_offset is valid, but o PNFS_BLOCK_INVALID_DATA means that storage_offset is valid, but
points to invalid un-initialized data. This data must not be points to invalid un-initialized data. This data must not be
physically read from the disk until it has been initialized. A physically read from the disk until it has been initialized. A
read request for a PNFS_BLOCK_INVALID_DATA extent must fill the read request for a PNFS_BLOCK_INVALID_DATA extent must fill the
user buffer with zeros. Write requests must write whole server- user buffer with zeros, unless the extent is covered by a
sized blocks to the disk; bytes not initialized by the user must PNFS_BLOCK_READ_DATA extent of a copy-on-write file system. Write
be set to zero. Any write to storage in a PNFS_BLOCK_INVALID_DATA requests must write whole server-sized blocks to the disk; bytes
extent changes the written portion of the extent to not initialized by the user must be set to zero. Any write to
PNFS_BLOCK_READ_WRITE_DATA; the pNFS client is responsible for storage in a PNFS_BLOCK_INVALID_DATA extent changes the written
reporting this change via LAYOUTCOMMIT. portion of the extent to PNFS_BLOCK_READ_WRITE_DATA; the pNFS
client is responsible for reporting this change via LAYOUTCOMMIT.
o PNFS_BLOCK_NONE_DATA means that storage_offset is not valid, and o PNFS_BLOCK_NONE_DATA means that storage_offset is not valid, and
this extent may not be used to satisfy write requests. Read this extent may not be used to satisfy write requests. Read
requests may be satisfied by zero-filling as for requests may be satisfied by zero-filling as for
PNFS_BLOCK_INVALID_DATA. PNFS_BLOCK_NONE_DATA extents may be PNFS_BLOCK_INVALID_DATA. PNFS_BLOCK_NONE_DATA extents may be
returned by requests for readable extents; they are never returned returned by requests for readable extents; they are never returned
if the request was for a writeable extent. if the request was for a writeable extent.
An extent list lists all relevant extents in increasing order of the An extent list lists all relevant extents in increasing order of the
file_offset of each extent; any ties are broken by increasing order file_offset of each extent; any ties are broken by increasing order
skipping to change at page 12, line 34 skipping to change at page 12, line 46
PNFS_BLOCK_READ_DATA or PNFS_BLOCK_NONE_DATA extents (but not PNFS_BLOCK_READ_DATA or PNFS_BLOCK_NONE_DATA extents (but not
PNFS_BLOCK_INVALID_DATA or PNFS_BLOCK_READ_WRITE_DATA extents). PNFS_BLOCK_INVALID_DATA or PNFS_BLOCK_READ_WRITE_DATA extents).
o A request for a writeable layout returns o A request for a writeable layout returns
PNFS_BLOCK_READ_WRITE_DATA or PNFS_BLOCK_INVALID_DATA extents (but PNFS_BLOCK_READ_WRITE_DATA or PNFS_BLOCK_INVALID_DATA extents (but
not PNFS_BLOCK_NONE_DATA extents). It may also return not PNFS_BLOCK_NONE_DATA extents). It may also return
PNFS_BLOCK_READ_DATA extents only when the offset ranges in those PNFS_BLOCK_READ_DATA extents only when the offset ranges in those
extents are also covered by PNFS_BLOCK_INVALID_DATA extents to extents are also covered by PNFS_BLOCK_INVALID_DATA extents to
permit writes. permit writes.
o The first extent in the list MUST contain the starting offset. o The first extent in the list MUST contain the requested starting
offset.
o The total size of extents in the extent list MUST cover at least o The total size of extents within the requested range MUST cover at
the minimum size. One exception is allowed: the total size MAY be least the minimum size. One exception is allowed: the total size
smaller if only readable extents were requested and EOF is MAY be smaller if only readable extents were requested and EOF is
encountered. encountered.
o Extents in the extent list MUST be logically contiguous for a o Extents in the extent list MUST be logically contiguous for a
read-only layout. For a read-write layout, the set of writable read-only layout. For a read-write layout, the set of writable
extents (i.e., excluding PNFS_BLOCK_READ_DATA extents) MUST be extents (i.e., excluding PNFS_BLOCK_READ_DATA extents) MUST be
logically contiguous. Every PNFS_BLOCK_READ_DATA extent in a logically contiguous. Every PNFS_BLOCK_READ_DATA extent in a
read-write layout MUST be covered by a PNFS_BLOCK_INVALID_DATA read-write layout MUST be covered by one or more
extent. This overlap of PNFS_BLOCK_READ_DATA and PNFS_BLOCK_INVALID_DATA extents. This overlap of
PNFS_BLOCK_INVALID_DATA extents is the only permitted extent PNFS_BLOCK_READ_DATA and PNFS_BLOCK_INVALID_DATA extents is the
overlap. only permitted extent overlap.
o Extents MUST be ordered in the list by starting offset, with o Extents MUST be ordered in the list by starting offset, with
PNFS_BLOCK_READ_DATA extents preceding PNFS_BLOCK_INVALID_DATA PNFS_BLOCK_READ_DATA extents preceding PNFS_BLOCK_INVALID_DATA
extents in the case of equal file_offsets. extents in the case of equal file_offsets.
2.3.2. Layout Commits 2.3.2. Layout Commits
struct pnfs_block_layoutupdate4 { struct pnfs_block_layoutupdate4 {
pnfs_block_extent4 commit_list<>; /* list of extents which now pnfs_block_extent4 commit_list<>; /* list of extents which now
contain valid data. */ contain valid data. */
}; };
The "pnfs_block_layoutupdate4" structure is used by the client as the The "pnfs_block_layoutupdate4" structure is used by the client as the
block-protocol specific argument in a LAYOUTCOMMIT operation. The block-protocol specific argument in a LAYOUTCOMMIT operation. The
"commit_list" field is an extent list covering regions of the file "commit_list" field is an extent list covering regions of the file
layout that were previously in the PNFS_BLOCK_INVALID_DATA state, but layout that were previously in the PNFS_BLOCK_INVALID_DATA state, but
have been written by the client and should now be considered in the have been written by the client and should now be considered in the
PNFS_BLOCK_READ_WRITE_DATA state. The es field of each extent in the PNFS_BLOCK_READ_WRITE_DATA state. The es field of each extent in the
commit_list MUST be set to PNFS_BLOCK_READ_WRITE_DATA. Implementers commit_list MUST be set to PNFS_BLOCK_READ_WRITE_DATA. The extents
in the commit list MUST be disjoint and MUST be sorted by
file_offset. The storage_offset field is unused. Implementers
should be aware that a server may be unable to commit regions at a should be aware that a server may be unable to commit regions at a
granularity smaller than a file-system block (typically 4KB or 8KB). granularity smaller than a file-system block (typically 4KB or 8KB).
As noted above, the block-size that the server uses is available as As noted above, the block-size that the server uses is available as
an NFSv4 attribute, and any extents included in the "commit_list" an NFSv4 attribute, and any extents included in the "commit_list"
MUST be aligned to this granularity and have a size that is a MUST be aligned to this granularity and have a size that is a
multiple of this granularity. If the client believes that its multiple of this granularity. If the client believes that its
actions have moved the end-of-file into the middle of a block being actions have moved the end-of-file into the middle of a block being
committed, the client MUST write zeroes from the end-of-file to the committed, the client MUST write zeroes from the end-of-file to the
end of that block before committing the block. Failure to do so may end of that block before committing the block. Failure to do so may
result in junk (uninitialized data) appearing in that area if the result in junk (uninitialized data) appearing in that area if the
skipping to change at page 17, line 49 skipping to change at page 18, line 20
the current end-of-file, or extended explicitly by a SETATTR request, the current end-of-file, or extended explicitly by a SETATTR request,
the server need not recall any portions of any pNFS layouts. the server need not recall any portions of any pNFS layouts.
2.3.7. Layout Hints 2.3.7. Layout Hints
The SETATTR operation supports a layout hint attribute [NFSv4.1]. The SETATTR operation supports a layout hint attribute [NFSv4.1].
When the client sets a layout hint (data type layouthint4) with a When the client sets a layout hint (data type layouthint4) with a
layout type of LAYOUT4_BLOCK_VOLUME (the loh_type field), the layout type of LAYOUT4_BLOCK_VOLUME (the loh_type field), the
loh_body field contains a value of data type pnfs_block_layouthint4. loh_body field contains a value of data type pnfs_block_layouthint4.
struct pnfs_block_layouthint4 { ///struct pnfs_block_layouthint4 {
uint64_t maximum_io_time; /* maximum i/o time in seconds /// uint64_t maximum_io_time; /* maximum i/o time in seconds
*/ /// */
///};
}; ///
The block layout client uses the layout hint data structure to The block layout client uses the layout hint data structure to
communicate to the server the maximum time that it may take an I/O to communicate to the server the maximum time that it may take an I/O to
execute on the client. Clients using block layouts it MUST set the execute on the client. Clients using block layouts it MUST set the
layout hint attribute before using LAYOUTGET operations. layout hint attribute before using LAYOUTGET operations.
2.3.8. Client Fencing 2.3.8. Client Fencing
The pNFS block protocol must handle situations in which a system The pNFS block protocol must handle situations in which a system
failure, typically a network connectivity issue, requires the server failure, typically a network connectivity issue, requires the server
skipping to change at page 23, line 30 skipping to change at page 23, line 47
This draft specifies the block/volume layout type for pNFS and This draft specifies the block/volume layout type for pNFS and
associated functionality. associated functionality.
5. IANA Considerations 5. IANA Considerations
There are no IANA considerations in this document. All pNFS IANA There are no IANA considerations in this document. All pNFS IANA
Considerations are covered in [NFSV4.1]. Considerations are covered in [NFSV4.1].
6. Acknowledgments 6. Acknowledgments
This draft draws extensively on the authors' familiarity with the 7. This draft draws extensively on the authors' familiarity with the
mapping functionality and protocol in EMC's HighRoad system mapping functionality and protocol in EMC's HighRoad system
[HighRoad]. The protocol used by HighRoad is called FMP (File [HighRoad]. The protocol used by HighRoad is called FMP (File
Mapping Protocol); it is an add-on protocol that runs in parallel Mapping Protocol); it is an add-on protocol that runs in parallel
with file system protocols such as NFSv3 to provide pNFS-like with file system protocols such as NFSv3 to provide pNFS-like
functionality for block/volume storage. While drawing on HighRoad functionality for block/volume storage. While drawing on HighRoad
FMP, the data structures and functional considerations in this draft FMP, the data structures and functional considerations in this draft
differ in significant ways, based on lessons learned and the differ in significant ways, based on lessons learned and the
opportunity to take advantage of NFSv4 features such as COMPOUND opportunity to take advantage of NFSv4 features such as COMPOUND
operations. The design to support pNFS client participation in copy- operations. The design to support pNFS client participation in copy-
on-write is based on text and ideas contributed by Craig Everhart on-write is based on text and ideas contributed by Craig Everhart
(formerly with IBM). (formerly with IBM).References
7. References
7.1. Normative References 7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[NFSV4.1] Shepler, S., Eisler, M., and Noveck, D. ed., "NFSv4 Minor [NFSV4.1] Shepler, S., Eisler, M., and Noveck, D. ed., "NFSv4 Minor
Version 1", draft-ietf-nfsv4-minorversion1-14.txt, Internet Version 1", draft-ietf-nfsv4-minorversion1-14.txt, Internet
Draft, July 2007. Draft, July 2007.
[XDR] Eisler, M., "XDR: External Data Representation Standard",
STD 67, RFC 4506, May 2006.
7.2. Informative References 7.2. Informative References
[HighRoad] EMC Corporation, "EMC Celerra HighRoad", EMC C819.1 white [HighRoad] EMC Corporation, "EMC Celerra HighRoad", EMC C819.1 white
paper, available at: paper, available at:
http://www.emc.com/pdf/products/celerra_file_server/HighRoad_wp.pdf http://www.emc.com/pdf/products/celerra_file_server/HighRoad_wp.pdf
link checked 29 August 2006. link checked 29 August 2006.
[SMIS] SNIA, "SNIA Storage Management Initiative Specification", [SMIS] SNIA, "SNIA Storage Management Initiative Specification",
version 1.0.2, available at: version 1.0.2, available at:
http://www.snia.org/smi/tech_activities/smi_spec_pr/spec/SMIS_1_0_2_f http://www.snia.org/smi/tech_activities/smi_spec_pr/spec/SMIS_1_0_2_f
inal.pdf inal.pdf
Author's Addresses Authors' Addresses
David L. Black David L. Black
EMC Corporation EMC Corporation
176 South Street 176 South Street
Hopkinton, MA 01748 Hopkinton, MA 01748
Phone: +1 (508) 293-7953 Phone: +1 (508) 293-7953
Email: black_david@emc.com Email: black_david@emc.com
Stephen Fridella Stephen Fridella
EMC Corporation EMC Corporation
228 South Street 228 South Street
Hopkinton, MA 01748 Hopkinton, MA 01748
Phone: +1 (508) 249-3528 Phone: +1 (508) 249-3528
Email: fridella_stephen@emc.com Email: fridella_stephen@emc.com
Jason Glasgow Jason Glasgow
EMC Corporation EMC Corporation
skipping to change at page 25, line 41 skipping to change at page 26, line 11
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement Copyright Statement
Copyright (C) The IETF Trust (2007). Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
Acknowledgment Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is currently provided by the
Internet Society. Internet Society.
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