< draft-ietf-nfsv4-rfc5667bis-05.txt   draft-ietf-nfsv4-rfc5667bis-06.txt >
Network File System Version 4 C. Lever, Ed. Network File System Version 4 C. Lever, Ed.
Internet-Draft Oracle Internet-Draft Oracle
Obsoletes: 5667 (if approved) February 3, 2017 Obsoletes: 5667 (if approved) February 24, 2017
Intended status: Standards Track Intended status: Standards Track
Expires: August 7, 2017 Expires: August 28, 2017
Network File System (NFS) Upper Layer Binding To RPC-Over-RDMA Network File System (NFS) Upper Layer Binding To RPC-Over-RDMA Version
draft-ietf-nfsv4-rfc5667bis-05 One
draft-ietf-nfsv4-rfc5667bis-06
Abstract Abstract
This document specifies Upper Layer Bindings of Network File System This document specifies Upper Layer Bindings of Network File System
(NFS) protocol versions to RPC-over-RDMA. Upper Layer Bindings are (NFS) protocol versions to RPC-over-RDMA Version One. Upper Layer
required to enable RPC-based protocols, such as NFS, to use Direct Bindings are required in order to enable RPC-based protocols such as
Data Placement on RPC-over-RDMA. This document obsoletes RFC 5667. NFS to use Direct Data Placement on RPC-over-RDMA Version One. This
document obsoletes RFC 5667.
Requirements Language Requirements Language
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].
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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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 August 7, 2017. This Internet-Draft will expire on August 28, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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modifications of such material outside the IETF Standards Process. modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling Without obtaining an adequate license from the person(s) controlling
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outside the IETF Standards Process, and derivative works of it may outside the IETF Standards Process, and derivative works of it may
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than English. than English.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conveying NFS Operations On RPC-Over-RDMA . . . . . . . . . . 3 2. Reply Size Estimation . . . . . . . . . . . . . . . . . . . . 3
3. Upper Layer Binding For NFS Versions 2 And 3 . . . . . . . . 4 2.1. Short Reply Chunk Retry . . . . . . . . . . . . . . . . . 4
4. Upper Layer Binding For NFS Version 4 . . . . . . . . . . . . 6 3. Upper Layer Binding for NFS Versions 2 and 3 . . . . . . . . 5
5. Extending NFS Upper Layer Bindings . . . . . . . . . . . . . 12 3.1. Reply Size Estimation . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 3.2. RPC Binding Considerations . . . . . . . . . . . . . . . 5
7. Security Considerations . . . . . . . . . . . . . . . . . . . 13 4. Upper Layer Bindings for NFS Version 2 and 3 Auxiliary
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Appendix A. Changes Since RFC 5667 . . . . . . . . . . . . . . . 15 4.1. MOUNT, NLM, and NSM Protocols . . . . . . . . . . . . . . 6
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 17 4.2. NFSACL Protocol . . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 17 5. Upper Layer Binding For NFS Version 4 . . . . . . . . . . . . 7
5.1. DDP-Eligibility . . . . . . . . . . . . . . . . . . . . . 7
5.2. Reply Size Estimation . . . . . . . . . . . . . . . . . . 8
5.3. RPC Binding Considerations . . . . . . . . . . . . . . . 9
5.4. NFS COMPOUND Requests . . . . . . . . . . . . . . . . . . 10
5.5. NFS Callback Requests . . . . . . . . . . . . . . . . . . 11
5.6. Session-Related Considerations . . . . . . . . . . . . . 12
5.7. Transport Considerations . . . . . . . . . . . . . . . . 13
6. Extending NFS Upper Layer Bindings . . . . . . . . . . . . . 14
7. Security Considerations . . . . . . . . . . . . . . . . . . . 14
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.1. Normative References . . . . . . . . . . . . . . . . . . 15
9.2. Informative References . . . . . . . . . . . . . . . . . 16
Appendix A. Changes Since RFC 5667 . . . . . . . . . . . . . . . 17
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 18
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction 1. Introduction
An RPC-over-RDMA transport, such as the one defined in An RPC-over-RDMA Version One transport may employ direct data
[I-D.ietf-nfsv4-rfc5666bis], may employ direct data placement to placement to convey certain data payloads associated with RPC
convey data payloads associated with RPC transactions. To enable transactions [I-D.ietf-nfsv4-rfc5666bis]. To enable successful
successful interoperation, RPC client and server implementations must interoperation, implementations of RPC Programs running on RPC-over-
agree as to which XDR data items in what particular RPC procedures RDMA must agree as to which XDR data items in what particular RPC
are eligible for direct data placement (DDP). procedures are eligible for direct data placement (DDP). This
agreement is specified in an Upper Layer Binding.
This document contains material required of Upper Layer Bindings, as This document contains material required of Upper Layer Bindings, as
specified in [I-D.ietf-nfsv4-rfc5666bis], for the following NFS specified in [I-D.ietf-nfsv4-rfc5666bis], for the following NFS
protocol versions: protocol versions:
o NFS Version 2 [RFC1094] o NFS Version 2 [RFC1094]
o NFS Version 3 [RFC1813] o NFS Version 3 [RFC1813]
o NFS Version 4.0 [RFC7530] o NFS Version 4.0 [RFC7530]
o NFS Version 4.1 [RFC5661] o NFS Version 4.1 [RFC5661]
o NFS Version 4.2 [RFC7862] o NFS Version 4.2 [RFC7862]
Upper Layer Bindings specified in this document apply to all versions This document assumes the reader is already familiar with concepts
of RPC-over-RDMA. and terminology defined in [I-D.ietf-nfsv4-rfc5666bis] and the
documents it references.
2. Conveying NFS Operations On RPC-Over-RDMA 2. Reply Size Estimation
Definitions of terminology and a general discussion of how RPC-over- On an RPC-over-RDMA Version One transport, during the construction of
RDMA is used to convey RPC transactions can be found in each RPC Call message, a requester is responsible for allocating
[I-D.ietf-nfsv4-rfc5666bis]. In this section, these general appropriate resources for receiving the matching Reply message.
principles are applied in the context of conveying NFS procedures on
RPC-over-RDMA. Some issues common to all NFS protocol versions are
introduced.
2.1. DDP Eligibility Violations An overrun of these resources can result in corruption of the Reply
message or termination of the transport connection. Therefore
reliable reply size estimation is necessary to ensure successful
interoperation. This is particularly critical, for example, when
allocating a Reply chunk.
To report a DDP-eligibity violation, an NFS server MUST return one In most cases, the NFS protocol's XDR definition provides enough
of: information to enable an NFS client to predict the maximum size of
the expected Reply message. If there are variable-size data items in
the result, the maximum size of the RPC Reply message can be
estimated as follows:
o An RPC-over-RDMA message of type RDMA_ERROR, with the rdma_xid o The client requests only a specific portion of an object (for
field set to the XID of the matching NFS Call, and the rdma_error example, using the "count" and "offset" fields in an NFS READ).
field set to ERR_CHUNK; or
o An RPC message (via an RDMA_MSG message) with the xid field set to o The client has already cached the size of the whole object it is
the XID of the matching NFS Call, the mtype field set to REPLY, about to request (say, via a previous NFS GETATTR request).
the stat field set to MSG_ACCEPTED, and the accept_stat field set
to GARBAGE_ARGS.
Subsequent sections of this document describe further considerations o The client and server have negotiated a maximum size for all calls
particular to specific NFS protocols or procedures. and responses (using a CREATE_SESSION operation, for instance).
2.2. Reply Size Estimation 2.1. Short Reply Chunk Retry
During the construction of each RPC Call message, an NFS client is In a few cases, either the size of one or more returned data items or
responsible for allocating appropriate resources for receiving the the number of returned data items cannot be known in advance of
matching Reply message. A Reply buffer overrun can result in forming an RPC Call.
corruption of the Reply message or termination of the transport
connection. Therefore reliable reply size estimation is necessary to
ensure successful interoperation. This is particularly critical, for
example, when allocating a Reply chunk.
In many cases the Upper Layer Protocol's XDR definition provides A requester uses a Reply chunk to handle an RPC transaction where the
enough information to enable the client to make a reliable prediction expected RPC Reply message might be larger than the requester's
of the maximum size of the expected Reply message. If there are inline threshold. If an actual RPC Reply message does not fit in a
variable-size data items in the result, the maximum size of the RPC client-provided Reply chunk, the NFS server responds with an
Reply message can be reliably estimated in most cases: RDMA_ERROR message with the rdma_err field set to ERR_CHUNK, or it
could even break the transport connection.
o The client requests only a specific portion of an object (for In response, an NFS client can choose to:
example, using the "count" and "offset" fields in an NFS READ).
o The client has already cached the size of the whole object it is o Terminate the RPC transaction with an error, or
about to request (say, via a previous NFS GETATTR request).
o The client and server have negotiated a maximum size for all calls o Allocate a larger Reply chunk and send the same request as a new
and responses. RPC transaction (to avoid hitting in a Duplicate Reply Cache).
The NFS client should avoid retrying the request indefinitely
because a responder may return ERR_CHUNK for a variety of reasons.
Subsequent sections of this document describe considerations The latter choice is considered heroic recovery, and is only a real
particular to specific NFS procedures where it is not possible to choice for the few operations where it is not possible for an NFS
determine the maximum Reply message size based solely on the above client to predict the size of the Reply message in advance.
criteria.
3. Upper Layer Binding For NFS Versions 2 And 3 Subsequent sections of this document discuss exactly which operations
might have ultimate difficulty with Reply size estimation. These
operations are eligible for "short Reply chunk retry." Unless
explicitly mentioned as applicable, short Reply chunk retry should
not be used.
This Upper Layer Binding specification applies to NFS Version 2 3. Upper Layer Binding for NFS Versions 2 and 3
[RFC1094] and NFS Version 3 [RFC1813]. For brevity, in this section
a "legacy NFS client" refers to an NFS client using NFS version 2 or The Upper Layer Binding specification in this section applies to NFS
NFS version 3 to communicate with an NFS server. Likewise, a "legacy Version 2 [RFC1094] and NFS Version 3 [RFC1813]. For brevity, in
NFS server" is an NFS server communicating with clients using NFS this document a "Legacy NFS client" refers to an NFS client using the
version 2 or NFS version 3. NFS version 2 or NFS version 3 RPC Programs (100003) to communicate
with an NFS server. Likewise, a "Legacy NFS server" is an NFS server
communicating with clients using NFS version 2 or NFS version 3.
The following XDR data items in NFS versions 2 and 3 are DDP- The following XDR data items in NFS versions 2 and 3 are DDP-
eligible: eligible:
o The opaque file data argument in the NFS WRITE procedure o The opaque file data argument in the NFS WRITE procedure
o The pathname argument in the NFS SYMLINK procedure o The pathname argument in the NFS SYMLINK procedure
o The opaque file data result in the NFS READ procedure o The opaque file data result in the NFS READ procedure
o The pathname result in the NFS READLINK procedure o The pathname result in the NFS READLINK procedure
All other argument or result data items in NFS versions 2 and 3 are All other argument or result data items in NFS versions 2 and 3 are
not DDP-eligible. not DDP-eligible.
A legacy server's response to a DDP-eligibility violation (described A Legacy NFS client MUST NOT send a reduced Payload stream in a Long
in Section 2.1) does not give an indication to legacy clients of Call. A Legacy NFS client MUST NOT enable a Legacy NFS server to
whether the server has processed the arguments of the RPC Call, or send a reduced Payload stream in a Long Reply.
whether the server has accessed or modified client memory associated
with that RPC.
A legacy NFS client determines the maximum reply size for each A Legacy server's response to a DDP-eligibility violation does not
operation using the basic criteria outlined in Section 2.2. give an indication to Legacy clients of whether the server has
processed the arguments of the RPC Call, or whether the server has
accessed or modified client memory associated with that RPC.
3.1. Auxiliary Protocols 3.1. Reply Size Estimation
A Legacy NFS client determines the maximum reply size for each
operation using the criteria outlined in Section 2. There are no
operations in NFS version 2 or 3 that benefit from short Reply chunk
retry.
3.2. RPC Binding Considerations
Legacy NFS servers traditionally listen for clients on UDP and TCP
port 2049. Additionally, they register these ports with a local
portmapper [RFC1833] service.
A Legacy NFS server supporting RPC-over-RDMA Version One on such a
network and registering itself with the RPC portmapper MAY choose an
arbitrary port, or MAY use the alternative well-known port number for
its RPC-over-RDMA service (see Section 8). The chosen port MAY be
registered with the RPC portmapper under the netids assigned in
[I-D.ietf-nfsv4-rfc5666bis].
4. Upper Layer Bindings for NFS Version 2 and 3 Auxiliary Protocols
NFS versions 2 and 3 are typically deployed with several other NFS versions 2 and 3 are typically deployed with several other
protocols, sometimes referred to as "NFS auxiliary protocols." These protocols, sometimes referred to as "NFS auxiliary protocols." These
are separate RPC programs that define procedures which are not part are distinct RPC Programs that define procedures which are not part
of the NFS version 2 or version 3 RPC programs. These include: of the NFS version 2 or version 3 RPC Programs. The Upper Layer
Bindings in this section apply to:
o The MOUNT and NLM protocols, introduced in an appendix of o The MOUNT and NLM protocols, introduced in an appendix of
[RFC1813] [RFC1813]
o The NSM protocol, described in Chapter 11 of [NSM] o The NSM protocol, described in Chapter 11 of [NSM]
o The NFSACL protocol, which does not have a public definition o The NFSACL protocol, which does not have a public definition.
(NFSACL here is treated as a de facto standard as there are NFSACL is treated in this document as a de facto standard, as
several interoperating implementations). there are several interoperating implementations.
RPC-over-RDMA considers these programs as distinct Upper Layer RPC-over-RDMA Version One considers these RPC Programs as separate
Protocols [I-D.ietf-nfsv4-rfc5666bis]. To enable the use of these Upper Layer Protocols [I-D.ietf-nfsv4-rfc5666bis]. Therefore a
ULPs on an RPC-over-RDMA transport, an Upper Layer Binding separate Upper Layer Binding, provided here, is required for each of
specification is provided here for each. these.
3.1.1. MOUNT, NLM, And NSM Protocols 4.1. MOUNT, NLM, and NSM Protocols
Typically MOUNT, NLM, and NSM are conveyed via TCP, even in Typically MOUNT, NLM, and NSM are conveyed via TCP, even in
deployments where NFS operations on RPC-over-RDMA. When a legacy deployments where the NFS RPC Program operates on RPC-over-RDMA
server supports these programs on RPC-over-RDMA, it advertises the Version One. When a Legacy server supports these RPC Programs on
port address via the usual rpcbind service [RFC1833]. RPC-over-RDMA Version One, it advertises the port address via the
usual rpcbind service [RFC1833].
No operation in these protocols conveys a significant data payload, No operation in these protocols conveys a significant data payload,
and the size of RPC messages in these protocols is uniformly small. and the size of RPC messages in these protocols is uniformly small.
Therefore, no XDR data items in these protocols are DDP-eligible. Therefore, no XDR data items in these protocols are DDP-eligible.
The largest variable-length XDR data item is an xdr_netobj. In most The largest variable-length XDR data item is an xdr_netobj. In most
implementations this data item is not larger than 1024 bytes, making implementations this data item is never larger than 1024 bytes,
reliable reply size estimation straightforward using the criteria making reliable reply size estimation straightforward using the
outlined in Section 2.2. criteria outlined in Section 2. There are no operations in these
protocols that benefit from short Reply chunk retry.
3.1.2. NFSACL Protocol 4.2. NFSACL Protocol
Legacy clients and servers that support the NFSACL RPC program Legacy clients and servers that support the NFSACL RPC Program
typically convey NFSACL procedures on the same connection as the NFS typically convey NFSACL procedures on the same connection as NFS RPC
RPC program. This obviates the need for separate rpcbind queries to Programs. This obviates the need for separate rpcbind queries to
discover server support for this RPC program. discover server support for this RPC Program.
ACLs are typically small, but even large ACLs must be encoded and ACLs are typically small, but even large ACLs must be encoded and
decoded to some degree. Thus no data item in this Upper Layer decoded to some degree. Thus no data item in this Upper Layer
Protocol is DDP-eligible. Protocol is DDP-eligible.
For procedures whose replies do not include an ACL object, the size For procedures whose replies do not include an ACL object, the size
of a reply is determined directly from the NFSACL program's XDR of a reply is determined directly from the NFSACL RPC Program's XDR
definition. definition.
There is no protocol-wide size limit for NFS version 3 ACLs, and There is no protocol-specified size limit for NFS version 3 ACLs, and
there is no mechanism in either the NFSACL or NFS programs for a there is no mechanism in either the NFSACL or NFS RPC Programs for a
legacy client to ascertain the largest ACL a legacy server can store. Legacy client to ascertain the largest ACL a Legacy server can
Legacy client implementations should choose a maximum size for ACLs return. Legacy client implementations should choose a maximum size
based on their own internal limits. A recommended lower bound for for ACLs based on their own internal limits.
this maximum is 32,768 bytes.
When an especially large ACL is expected, a Reply chunk might be
required. If a legacy NFS server indicates that it cannot return an
NFSACL GETACL response because the legacy NFS client has not provided
a large enough Reply chunk to receive that response, the legacy NFS
client can choose to
o Terminate the NFSACL GETACL with an error, or
o Allocate a larger Reply chunk and send the same NFSACL GETACL Because an NFSACL client cannot know in advance how large a returned
request as a new RPC transaction. The NFS client should avoid ACL will be, it can use short Reply chunk retry when an NFSACL GETACL
retrying the request indefinitely. operation encounters a transport error.
4. Upper Layer Binding For NFS Version 4 5. Upper Layer Binding For NFS Version 4
This Upper Layer Binding specification applies to all protocols The Upper Layer Binding specification in this section applies to RPC
defined in NFS Version 4.0 [RFC7530], NFS Version 4.1 [RFC5661], and Programs defined in NFS Version 4.0 [RFC7530], NFS Version 4.1
NFS Version 4.2 [RFC7862]. [RFC5661], and NFS Version 4.2 [RFC7862].
4.1. DDP-Eligibility 5.1. DDP-Eligibility
Only the following XDR data items in the COMPOUND procedure of all Only the following XDR data items in the COMPOUND procedure of all
NFS version 4 minor versions are DDP-eligible: NFS version 4 minor versions are DDP-eligible:
o The opaque data field in the WRITE4args structure o The opaque data field in the WRITE4args structure
o The linkdata field of the NF4LNK arm in the createtype4 union o The linkdata field of the NF4LNK arm in the createtype4 union
o The opaque data field in the READ4resok structure o The opaque data field in the READ4resok structure
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Only the following XDR data items in the COMPOUND procedure of all Only the following XDR data items in the COMPOUND procedure of all
NFS version 4 minor versions are DDP-eligible: NFS version 4 minor versions are DDP-eligible:
o The opaque data field in the WRITE4args structure o The opaque data field in the WRITE4args structure
o The linkdata field of the NF4LNK arm in the createtype4 union o The linkdata field of the NF4LNK arm in the createtype4 union
o The opaque data field in the READ4resok structure o The opaque data field in the READ4resok structure
o The linkdata field in the READLINK4resok structure o The linkdata field in the READLINK4resok structure
o In minor version 2 and newer, the rpc_data field of the o In minor version 2 and newer, the rpc_data field of the
read_plus_content union (further restrictions on the use of this read_plus_content union (further restrictions on the use of this
data item follow below). data item follow below).
4.1.1. READ_PLUS Replies 5.1.1. READ_PLUS Replies
The NFS version 4.2 READ_PLUS operation returns a complex data type The NFS version 4.2 READ_PLUS operation returns a complex data type
[RFC7862]. The rpr_contents field in the result of this operation is [RFC7862]. The rpr_contents field in the result of this operation is
an array of read_plus_content unions, one arm of which contains an an array of read_plus_content unions, one arm of which contains an
opaque byte stream (d_data). opaque byte stream (d_data).
The size of d_data is limited to the value of the rpa_count field, The size of d_data is limited to the value of the rpa_count field,
but the protocol does not bound the number of elements which can be but the protocol does not bound the number of elements which can be
returned in the rpr_contents array. In order to make the size of returned in the rpr_contents array. In order to make the size of
READ_PLUS replies predictable by NFS version 4.2 clients, the READ_PLUS replies predictable by NFS version 4.2 clients, the
following restrictions are placed on the use of the READ_PLUS following restrictions are placed on the use of the READ_PLUS
operation on RPC-over-RDMA transports: operation on an RPC-over-RDMA Version One transport:
o An NFS version 4.2 client MUST NOT provide more than one Write o An NFS version 4.2 client MUST NOT provide more than one Write
chunk for any READ_PLUS operation. When providing a Write chunk chunk for any READ_PLUS operation. When providing a Write chunk
for a READ_PLUS operation, an NFS version 4.2 client MUST provide for a READ_PLUS operation, an NFS version 4.2 client MUST provide
a Write chunk that is either empty (which forces all result data a Write chunk that is either empty (which forces all result data
items for this operation to be returned inline) or large enough to items for this operation to be returned inline) or large enough to
receive rpa_count bytes in a single element of the rpr_contents receive rpa_count bytes in a single element of the rpr_contents
array. array.
o If the Write chunk provided for a READ_PLUS operation by an NFS o If the Write chunk provided for a READ_PLUS operation by an NFS
skipping to change at page 7, line 42 skipping to change at page 8, line 39
use that chunk for the first element of the rpr_contents array use that chunk for the first element of the rpr_contents array
that has an rpc_data arm. that has an rpc_data arm.
o An NFS version 4.2 server MUST NOT return more than two elements o An NFS version 4.2 server MUST NOT return more than two elements
in the rpr_contents array of any READ_PLUS operation. It returns in the rpr_contents array of any READ_PLUS operation. It returns
as much of the requested byte range as it can fit within these two as much of the requested byte range as it can fit within these two
elements. If the NFS version 4.2 server has not asserted rpr_eof elements. If the NFS version 4.2 server has not asserted rpr_eof
in the reply, the NFS version 4.2 client SHOULD send additional in the reply, the NFS version 4.2 client SHOULD send additional
READ_PLUS requests for any remaining bytes. READ_PLUS requests for any remaining bytes.
4.2. NFS Version 4 Reply Size Estimation 5.2. Reply Size Estimation
Within NFS version 4, there are certain variable-length result data Within NFS version 4, there are certain variable-length result data
items whose maximum size cannot be estimated by clients reliably items whose maximum size cannot be estimated by clients reliably
because there is no protocol-specified size limit on these arrays. because there is no protocol-specified size limit on these arrays.
These include: These include:
o The attrlist4 field o The attrlist4 field
o Fields containing ACLs such as fattr4_acl, fattr4_dacl, o Fields containing ACLs such as fattr4_acl, fattr4_dacl,
fattr4_sacl fattr4_sacl
o Fields in the fs_locations4 and fs_locations_info4 data structures o Fields in the fs_locations4 and fs_locations_info4 data structures
o Fields opaque to the NFS version 4 protocol which pertain to pNFS o Fields opaque to the NFS version 4 protocol which pertain to pNFS
layout metadata, such as loc_body, loh_body, da_addr_body, layout metadata, such as loc_body, loh_body, da_addr_body,
lou_body, lrf_body, fattr_layout_types and fs_layout_types, lou_body, lrf_body, fattr_layout_types and fs_layout_types,
4.2.1. Reply Size Estimation For Minor Version 0 5.2.1. Reply Size Estimation for Minor Version 0
The NFSv4.0 protocol itself does not impose any bound on the size of The NFS version 4.0 protocol itself does not impose any bound on the
NFS calls or responses. size of NFS calls or responses.
Some of the data items enumerated in Section 4.2 (in particular, the Some of the data items enumerated in Section 5.2 (in particular, the
items related to ACLs and fs_locations) make it difficult to predict items related to ACLs and fs_locations) make it difficult to predict
the maximum size of NFSv4.0 GETATTR replies that interrogate the maximum size of NFS version 4.0 replies that interrogate
variable-length attributes. As discussed in Section 2.2, client variable-length fattr4 attributes. As discussed in Section 2, client
implementations can rely on their own internal architectural limits implementations can rely on their own internal architectural limits
to bound the reply size, but such limits are not always guaranteed to to constrain the reply size, but such limits are not always
be reliable. guaranteed to be reliable.
When an especially large NFSv4.0 GETATTR result is expected, a Reply
chunk might be required. If an NFSv4.0 server indicates that it
cannot return an NFSv4.0 GETATTR response because the requesting
NFSv4.0 client has not provided a large enough Reply chunk to receive
that response, the NFSv4.0 client can choose to
o Terminate the NFSv4.0 GETATTR with an error, or
o Allocate a larger Reply chunk and send the same NFSv4.0 GETATTR When an especially large fattr4 result is expected, a Reply chunk
request as a new RPC transaction. The NFS client should avoid might be required. An NFS version 4.0 client can use short Reply
retrying the request indefinitely. chunk retry when an NFS COMPOUND containing a GETATTR operation
encounters a transport error.
The use of NFS COMPOUND operations raises the possibility of requests The use of NFS COMPOUND operations raises the possibility of requests
that combine a non-idempotent operation (eg. NFS WRITE) with an that combine a non-idempotent operation (e.g. WRITE) with a GETATTR
NFSv4.0 GETATTR that requests one or more variable length results. operation that requests one or more variable-length results. This
This combination should be avoided by ensuring that any NFSv4.0 combination should be avoided by ensuring that any GETATTR operation
GETATTR operation that might return a result of unpredictable length that requests a result of unpredictable length is sent in an NFS
is sent in an NFS COMPOUND by itself. COMPOUND by itself.
4.2.2. Reply Size Estimation For Minor Version 1 And Newer 5.2.2. Reply Size Estimation for Minor Version 1 and Newer
In NFS version 4.1 and newer minor versions, the csa_fore_chan_attrs In NFS version 4.1 and newer minor versions, the csa_fore_chan_attrs
argument of the CREATE_SESSION operation contains a argument of the CREATE_SESSION operation contains a
ca_maxresponsesize field. The value in this field can be taken as ca_maxresponsesize field. The value in this field can be taken as
the absolute maximum size of replies generated by a replying NFS the absolute maximum size of replies generated by an NFS version 4.1
version 4 server. server.
This value can be used in cases where it is not possible to estimate This value can be used in cases where it is not possible to estimate
a reply size upper bound precisely. In practice, objects such as a reply size upper bound precisely. In practice, objects such as
ACLs, named attributes, layout bodies, and security labels are much ACLs, named attributes, layout bodies, and security labels are much
smaller than this maximum. smaller than this maximum.
4.3. NFS Version 4 COMPOUND Requests 5.3. RPC Binding Considerations
NFS version 4 servers are required to listen on TCP port 2049, and
they are not required to register with an rpcbind service [RFC7530].
Therefore, an NFS version 4 server supporting RPC-over-RDMA Version
One MUST use the alternative well-known port number for its RPC-over-
RDMA service (see Section 8). Clients SHOULD connect to this well-
known port without consulting the RPC portmapper (as for NFS version
4 on TCP transports).
5.4. NFS COMPOUND Requests
5.4.1. Long Calls and Replies
Each NFS version 4 COMPOUND procedure contains an array of operations
which may be larger than a connection's inline thresholds, even after
reduction of DDP-elibible payloads. Therefore, an NFS version 4
client MAY send a reduced Payload stream in a Long Call. An NFS
version 4 client MAY enable an NFS version 4 server to send a reduced
Payload stream in a Long Reply.
5.4.2. Multiple DDP-eligible Data Items
The NFS version 4 COMPOUND procedure allows the transmission of more The NFS version 4 COMPOUND procedure allows the transmission of more
than one DDP-eligible data item per Call and Reply message. An NFS than one DDP-eligible data item per Call and Reply message. An NFS
version 4 client provides XDR Position values in each Read chunk to version 4 client provides XDR Position values in each Read chunk to
disambiguate which chunk is associated with which argument data item. disambiguate which chunk is associated with which argument data item.
However NFS version 4 server and client implementations must agree in However NFS version 4 server and client implementations must agree in
advance on how to pair Write chunks with returned result data items. advance on how to pair Write chunks with returned result data items.
The mechanism specified in Section 4.3.2 of The mechanism specified in Section 4.3.2 of
[I-D.ietf-nfsv4-rfc5666bis]) is applied here, with additional [I-D.ietf-nfsv4-rfc5666bis]) is applied here, with additional
restrictions that appear below. In the following list, an "NFS Read" restrictions that appear below.
operation refers to any NFS Version 4 operation which has a DDP-
eligible result data item (i.e., either a READ, READ_PLUS, or In the following list, an "NFS Read" operation refers to any NFS
READLINK operation). Version 4 operation which has a DDP-eligible result data item (i.e.,
either a READ, READ_PLUS, or READLINK operation).
o If an NFS version 4 client wishes all DDP-eligible items in an NFS o If an NFS version 4 client wishes all DDP-eligible items in an NFS
reply to be conveyed inline, it leaves the Write list empty. reply to be conveyed inline, it leaves the Write list empty.
o The first chunk in the Write list MUST be used by the first READ o The first chunk in the Write list MUST be used by the first READ
operation in an NFS version 4 COMPOUND procedure. The next Write operation in an NFS version 4 COMPOUND procedure. The next Write
chunk is used by the next READ operation, and so on. chunk is used by the next READ operation, and so on.
o If an NFS version 4 client has provided a matching non-empty Write o If an NFS version 4 client has provided a matching non-empty Write
chunk, then the corresponding READ operation MUST return its DDP- chunk, then the corresponding READ operation MUST return its DDP-
skipping to change at page 10, line 5 skipping to change at page 11, line 14
o If a READ operation returns a union arm which does not contain a o If a READ operation returns a union arm which does not contain a
DDP-eligible result, and the NFS version 4 client has provided a DDP-eligible result, and the NFS version 4 client has provided a
matching non-empty Write chunk, an NFS version 4 server MUST matching non-empty Write chunk, an NFS version 4 server MUST
return an empty Write chunk in that Write list position. return an empty Write chunk in that Write list position.
o If there are more READ operations than Write chunks, then o If there are more READ operations than Write chunks, then
remaining NFS Read operations in an NFS version 4 COMPOUND that remaining NFS Read operations in an NFS version 4 COMPOUND that
have no matching Write chunk MUST return their results inline. have no matching Write chunk MUST return their results inline.
4.3.1. NFS Version 4 COMPOUND Example 5.4.3. NFS Version 4 COMPOUND Example
The following example shows a Write list with three Write chunks, A, The following example shows a Write list with three Write chunks, A,
B, and C. The NFS version 4 server consumes the provided Write B, and C. The NFS version 4 server consumes the provided Write
chunks by writing the results of the designated operations in the chunks by writing the results of the designated operations in the
compound request (READ and READLINK) back to each chunk. compound request (READ and READLINK) back to each chunk.
Write list: Write list:
A --> B --> C A --> B --> C
skipping to change at page 10, line 27 skipping to change at page 11, line 36
PUTFH LOOKUP READ PUTFH LOOKUP READLINK PUTFH LOOKUP READ PUTFH LOOKUP READ PUTFH LOOKUP READLINK PUTFH LOOKUP READ
| | | | | |
v v v v v v
A B C A B C
If the NFS version 4 client does not want to have the READLINK result If the NFS version 4 client does not want to have the READLINK result
returned via RDMA, it provides an empty Write chunk for buffer B to returned via RDMA, it provides an empty Write chunk for buffer B to
indicate that the READLINK result must be returned inline. indicate that the READLINK result must be returned inline.
4.4. NFS Version 4 Callback 5.5. NFS Callback Requests
The NFS version 4 protocols support server-initiated callbacks to The NFS version 4 family of protocols support server-initiated
notify clients of events such as recalled delegations. callbacks to notify NFS version 4 clients of events such as recalled
delegations.
4.4.1. NFS Version 4.0 Callback 5.5.1. NFS Version 4.0 Callback
NFS version 4.0 implementations typically employ a separate TCP NFS version 4.0 implementations typically employ a separate TCP
connection to handle callback operations, even when the forward connection to handle callback operations, even when the forward
channel uses a RPC-over-RDMA transport. channel uses an RPC-over-RDMA Version One transport.
No operation in the NFS version 4.0 callback RPC program conveys a No operation in the NFS version 4.0 callback RPC Program conveys a
significant data payload. Therefore, no XDR data items in this RPC significant data payload. Therefore, no XDR data items in this RPC
program is DDP-eligible. Program is DDP-eligible.
A CB_RECALL reply is small and fixed in size. The CB_GETATTR reply A CB_RECALL reply is small and fixed in size. The CB_GETATTR reply
contains a variable-length fattr4 data item. See Section 4.2.1 for a contains a variable-length fattr4 data item. See Section 5.2.1 for a
discussion of reply size prediction for this data item. discussion of reply size prediction for this data item.
An NFS version 4.0 client advertises netids and ad hoc port addresses An NFS version 4.0 client advertises netids and ad hoc port addresses
for contacting its NFS version 4.0 callback service using the for contacting its NFS version 4.0 callback service using the
SETCLIENTID operation. SETCLIENTID operation.
4.4.2. NFS Version 4.1 Callback 5.5.2. NFS Version 4.1 Callback
In NFS version 4.1 and newer minor versions, callback operations may In NFS version 4.1 and newer minor versions, callback operations may
appear on the same connection as is used for NFS version 4 forward appear on the same connection as is used for NFS version 4 forward
channel client requests. NFS version 4 clients and servers MUST use channel client requests. NFS version 4 clients and servers MUST use
the mechanism described in [I-D.ietf-nfsv4-rpcrdma-bidirection] when the mechanism described in [I-D.ietf-nfsv4-rpcrdma-bidirection] when
backchannel operations are conveyed on RPC-over-RDMA transports. backchannel operations are conveyed on RPC-over-RDMA Version One
transports.
The csa_back_chan_attrs argument of the CREATE_SESSION operation The csa_back_chan_attrs argument of the CREATE_SESSION operation
contains a ca_maxresponsesize field. The value in this field can be contains a ca_maxresponsesize field. The value in this field can be
taken as the absolute maximum size of backchannel replies generated taken as the absolute maximum size of backchannel replies generated
by a replying NFS version 4 client. by a replying NFS version 4 client.
There are no DDP-eligible data items in callback procedures defined There are no DDP-eligible data items in callback procedures defined
in NFS version 4.1 or NFS version 4.2. However, some callback in NFS version 4.1 or NFS version 4.2. However, some callback
operations, such as messages that convey device ID information, can operations, such as messages that convey device ID information, can
be large, in which case a Long Call or Reply might be required. be large, in which case a Long Call or Reply might be required.
When an NFS version 4.1 client can support Long Calls in its When an NFS version 4.1 client can support Long Calls in its
backchannel, it reports a backchannel ca_maxrequestsize that is backchannel, it reports a backchannel ca_maxrequestsize that is
larger than the connection's inline thresholds. Otherwise an NFS larger than the connection's inline thresholds. Otherwise an NFS
version 4 server MUST use only Short messages to convey backchannel version 4 server MUST use only Short messages to convey backchannel
operations. operations.
4.5. Session-Related Considerations 5.6. Session-Related Considerations
Typically the presence of an NFS session [RFC5661] has no effect on The presence of an NFS session (defined in [RFC5661]) has no effect
the operation of RPC-over-RDMA. None of the operations introduced to on the operation of RPC-over-RDMA Version One. None of the
support NFS sessions (eg. SEQUENCE) contain DDP-eligible data items. operations introduced to support NFS sessions (e.g. the SEQUENCE
There is no need to match the number of session slots with the number operation) contain DDP-eligible data items. There is no need to
of available RPC-over-RDMA credits. match the number of session slots with the number of available RPC-
over-RDMA credits.
When an NFS session operates on an RPC-over-RDMA transport, there are However, there are a few new cases where an RPC transaction can fail.
a few additional cases where an RPC transaction can fail. For For example, a requester might receive, in response to an RPC
example, a requester might receive, in response to an RPC request, an request, an RDMA_ERROR message with an rdma_err value of ERR_CHUNK,
RDMA_ERROR message with an rdma_err value of ERR_CHUNK, or an or an RDMA_MSG containing an RPC_GARBAGEARGS reply. These situations
RDMA_MSG containing an RPC_GARBAGEARGS reply. These situations are are no different from existing RPC errors which an NFS session
no different from existing RPC errors which an NFS session
implementation is already prepared to handle for other transports. implementation is already prepared to handle for other transports.
As with other transports during such a failure, there might be no And as with other transports during such a failure, there might be no
SEQUENCE result available to the requester to distinguish whether SEQUENCE result available to the requester to distinguish whether
failure occurred before or after the requested operations were failure occurred before or after the requested operations were
executed on the responder. When a transport error occurs (eg. executed on the responder.
RDMA_ERROR), the requester proceeds as usual to match the incoming
XID value to a waiting RPC Call. The RPC transaction is terminated,
and the result status is reported to the Upper Layer Protocol. The
requester's session implementation then determines the session ID and
slot for the failed request, and performs slot recovery to make that
slot usable again. If this is not done, that slot could be rendered
permanently unavailable.
4.6. Retransmission And Keep-Alive When a transport error occurs (e.g. RDMA_ERROR), the requester
proceeds as usual to match the incoming XID value to a waiting RPC
Call. The RPC transaction is terminated, and the result status is
reported to the Upper Layer Protocol. The requester's session
implementation then determines the session ID and slot for the failed
request, and performs slot recovery to make that slot usable again.
If this is not done, that slot could be rendered permanently
unavailable.
5.7. Transport Considerations
5.7.1. Congestion Avoidance
Section 3.1 of [RFC7530] states:
Where an NFSv4 implementation supports operation over the IP
network protocol, the supported transport layer between NFS and IP
MUST be an IETF standardized transport protocol that is specified
to avoid network congestion; such transports include TCP and the
Stream Control Transmission Protocol (SCTP).
Section 2.9.1 of [RFC5661] further states:
Even if NFSv4.1 is used over a non-IP network protocol, it is
RECOMMENDED that the transport support congestion control.
It is permissible for a connectionless transport to be used under
NFSv4.1; however, reliable and in-order delivery of data combined
with congestion control by the connectionless transport is
REQUIRED. As a consequence, UDP by itself MUST NOT be used as an
NFSv4.1 transport.
RPC-over-RDMA Version One is constructed on a platform of RDMA
Reliable Connections [I-D.ietf-nfsv4-rfc5666bis] [RFC5041]. RDMA
Reliable Connections are reliable, connection-oriented transports
that guarantee in-order delivery, meeting all above requirements for
NFS version 4 transports.
5.7.2. Retransmission and Keep-alive
NFS version 4 client implementations often rely on a transport-layer NFS version 4 client implementations often rely on a transport-layer
keep-alive mechanism to detect when an NFS version 4 server has keep-alive mechanism to detect when an NFS version 4 server has
become unresponsive. When an NFS server is no longer responsive, become unresponsive. When an NFS server is no longer responsive,
client-side keep-alive terminates the connection, which in turn client-side keep-alive terminates the connection, which in turn
triggers reconnection and RPC retransmission. triggers reconnection and RPC retransmission.
Some RDMA transports (such as Reliable Connections on InfiniBand) Some RDMA transports (such as Reliable Connections on InfiniBand)
have no keep-alive mechanism. Without a disconnect or new RPC have no keep-alive mechanism. Without a disconnect or new RPC
traffic, such connections can remain alive long after an NFS server traffic, such connections can remain alive long after an NFS server
skipping to change at page 12, line 30 skipping to change at page 14, line 21
available RPC-over-RDMA credits on that transport connection, it will available RPC-over-RDMA credits on that transport connection, it will
forever await a reply before sending another RPC request. forever await a reply before sending another RPC request.
NFS version 4 clients SHOULD reserve one RPC-over-RDMA credit to use NFS version 4 clients SHOULD reserve one RPC-over-RDMA credit to use
for periodic server or connection health assessment. This credit can for periodic server or connection health assessment. This credit can
be used to drive an RPC request on an otherwise idle connection, be used to drive an RPC request on an otherwise idle connection,
triggering either a quick affirmative server response or immediate triggering either a quick affirmative server response or immediate
connection termination. connection termination.
In addition to network partition and request loss scenarios, RPC- In addition to network partition and request loss scenarios, RPC-
over-RDMA connections can be terminated when a Transport header is over-RDMA transport connections can be terminated when a Transport
malformed, messages are larger than receive resources, or when too header is malformed, Reply messages are larger than receive
many RPC-over-RDMA messages are sent at once. In such cases: resources, or when too many RPC-over-RDMA messages are sent at once.
In such cases:
o If there is a transport error indicated (ie, RDMA_ERROR) before o If there is a transport error indicated (ie, RDMA_ERROR) before
the disconnect or instead of a disconnect, the requester MUST the disconnect or instead of a disconnect, the requester MUST
respond to that error as prescribed by the specification of the respond to that error as prescribed by the specification of the
RPC transport. Then the NFS version 4 rules for handling RPC transport. Then the NFS version 4 rules for handling
retransmission apply. retransmission apply.
o If there is a transport disconnect and the responder has provided o If there is a transport disconnect and the responder has provided
no other response for a request, then only the NFS version 4 rules no other response for a request, then only the NFS version 4 rules
for handling retransmission apply. for handling retransmission apply.
5. Extending NFS Upper Layer Bindings 6. Extending NFS Upper Layer Bindings
RPC programs such as NFS are required to have an Upper Layer Binding RPC Programs such as NFS are required to have an Upper Layer Binding
specification to interoperate on RPC-over-RDMA transports specification to interoperate on RPC-over-RDMA Version One transports
[I-D.ietf-nfsv4-rfc5666bis]. Via standards action, the Upper Layer [I-D.ietf-nfsv4-rfc5666bis]. Via standards action, the Upper Layer
Binding specified in this document can be extended to cover versions Binding specified in this document can be extended to cover versions
of the NFS version 4 protocol specified after NFS version 4 minor of the NFS version 4 protocol specified after NFS version 4 minor
version 2, or separately published extensions to an existing NFS version 2, or separately published extensions to an existing NFS
version 4 minor version, as described in [I-D.ietf-nfsv4-versioning]. version 4 minor version, as described in [I-D.ietf-nfsv4-versioning].
6. IANA Considerations
NFS use of direct data placement introduces a need for an additional
NFS port number assignment for networks that share traditional UDP
and TCP port spaces with RDMA services. The iWARP [RFC5041]
[RFC5040] protocol is such an example (InfiniBand is not).
NFS servers for versions 2 and 3 [RFC1094] [RFC1813] traditionally
listen for clients on UDP and TCP port 2049, and additionally, they
register these with the portmapper and/or rpcbind [RFC1833] service.
However, [RFC7530] requires NFS version 4 servers to listen on TCP
port 2049, and they are not required to register.
An NFS version 2 or version 3 server supporting RPC-over-RDMA on such
a network and registering itself with the RPC portmapper MAY choose
an arbitrary port, or MAY use the alternative well-known port number
for its RPC-over-RDMA service. The chosen port MAY be registered
with the RPC portmapper under the netid assigned by the requirement
in [I-D.ietf-nfsv4-rfc5666bis].
An NFS version 4 server supporting RPC-over-RDMA on such a network
MUST use the alternative well-known port number for its RPC-over-RDMA
service. Clients SHOULD connect to this well-known port without
consulting the RPC portmapper (as for NFS version 4 on TCP
transports).
The port number assigned to an NFS service over an RPC-over-RDMA
transport is available from the IANA port registry [RFC3232].
7. Security Considerations 7. Security Considerations
RPC-over-RDMA supports all RPC security models, including RPCSEC_GSS RPC-over-RDMA Version One supports all RPC security models, including
security and transport-level security [RFC2203]. The choice of what RPCSEC_GSS security and transport-level security [RFC2203]. The
Direct Data Placement mechanism to convey RPC argument and results choice of what Direct Data Placement mechanism to convey RPC argument
does not affect this, since it changes only the method of data and results does not affect this, since it changes only the method of
transfer. Specifically, the requirements of data transfer. Specifically, the requirements of
[I-D.ietf-nfsv4-rfc5666bis] ensure that this choice does not [I-D.ietf-nfsv4-rfc5666bis] ensure that this choice does not
introduce new vulnerabilities. introduce new vulnerabilities.
Because this document defines only the binding of the NFS protocols Because this document defines only the binding of the NFS protocols
atop [I-D.ietf-nfsv4-rfc5666bis], all relevant security atop [I-D.ietf-nfsv4-rfc5666bis], all relevant security
considerations are therefore to be described at that layer. considerations are therefore to be described at that layer.
8. References 8. IANA Considerations
8.1. Normative References The use of direct data placement in NFS introduces a need for an
additional port number assignment for networks that share traditional
UDP and TCP port spaces with RDMA services. The iWARP protocol is
such an example [RFC5041] [RFC5040].
For this purpose, a set of transport protocol port number assignments
is specified by this document. IANA has assigned the following ports
for NFS/RDMA in the IANA port registry, according to the guidelines
described in [RFC6335].
nfsrdma 20049/tcp Network File System (NFS) over RDMA
nfsrdma 20049/udp Network File System (NFS) over RDMA
nfsrdma 20049/sctp Network File System (NFS) over RDMA
This document should be listed as the reference for the nfsrdma port
assignments. This document does not alter these assignments.
9. References
9.1. Normative References
[I-D.ietf-nfsv4-rfc5666bis] [I-D.ietf-nfsv4-rfc5666bis]
Lever, C., Simpson, W., and T. Talpey, "Remote Direct Lever, C., Simpson, W., and T. Talpey, "Remote Direct
Memory Access Transport for Remote Procedure Call, Version Memory Access Transport for Remote Procedure Call, Version
One", draft-ietf-nfsv4-rfc5666bis-09 (work in progress), One", draft-ietf-nfsv4-rfc5666bis-10 (work in progress),
January 2017. February 2017.
[I-D.ietf-nfsv4-rpcrdma-bidirection] [I-D.ietf-nfsv4-rpcrdma-bidirection]
Lever, C., "Bi-directional Remote Procedure Call On RPC- Lever, C., "Bi-directional Remote Procedure Call On RPC-
over-RDMA Transports", draft-ietf-nfsv4-rpcrdma- over-RDMA Transports", draft-ietf-nfsv4-rpcrdma-
bidirection-06 (work in progress), January 2017. bidirection-07 (work in progress), February 2017.
[RFC1833] Srinivasan, R., "Binding Protocols for ONC RPC Version 2", [RFC1833] Srinivasan, R., "Binding Protocols for ONC RPC Version 2",
RFC 1833, DOI 10.17487/RFC1833, August 1995, RFC 1833, DOI 10.17487/RFC1833, August 1995,
<http://www.rfc-editor.org/info/rfc1833>. <http://www.rfc-editor.org/info/rfc1833>.
[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, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC2203] Eisler, M., Chiu, A., and L. Ling, "RPCSEC_GSS Protocol [RFC2203] Eisler, M., Chiu, A., and L. Ling, "RPCSEC_GSS Protocol
Specification", RFC 2203, DOI 10.17487/RFC2203, September Specification", RFC 2203, DOI 10.17487/RFC2203, September
1997, <http://www.rfc-editor.org/info/rfc2203>. 1997, <http://www.rfc-editor.org/info/rfc2203>.
[RFC5661] Shepler, S., Ed., Eisler, M., Ed., and D. Noveck, Ed., [RFC5661] Shepler, S., Ed., Eisler, M., Ed., and D. Noveck, Ed.,
"Network File System (NFS) Version 4 Minor Version 1 "Network File System (NFS) Version 4 Minor Version 1
Protocol", RFC 5661, DOI 10.17487/RFC5661, January 2010, Protocol", RFC 5661, DOI 10.17487/RFC5661, January 2010,
<http://www.rfc-editor.org/info/rfc5661>. <http://www.rfc-editor.org/info/rfc5661>.
[RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
Cheshire, "Internet Assigned Numbers Authority (IANA)
Procedures for the Management of the Service Name and
Transport Protocol Port Number Registry", BCP 165,
RFC 6335, DOI 10.17487/RFC6335, August 2011,
<http://www.rfc-editor.org/info/rfc6335>.
[RFC7530] Haynes, T., Ed. and D. Noveck, Ed., "Network File System [RFC7530] Haynes, T., Ed. and D. Noveck, Ed., "Network File System
(NFS) Version 4 Protocol", RFC 7530, DOI 10.17487/RFC7530, (NFS) Version 4 Protocol", RFC 7530, DOI 10.17487/RFC7530,
March 2015, <http://www.rfc-editor.org/info/rfc7530>. March 2015, <http://www.rfc-editor.org/info/rfc7530>.
[RFC7862] Haynes, T., "Network File System (NFS) Version 4 Minor [RFC7862] Haynes, T., "Network File System (NFS) Version 4 Minor
Version 2 Protocol", RFC 7862, DOI 10.17487/RFC7862, Version 2 Protocol", RFC 7862, DOI 10.17487/RFC7862,
November 2016, <http://www.rfc-editor.org/info/rfc7862>. November 2016, <http://www.rfc-editor.org/info/rfc7862>.
8.2. Informative References 9.2. Informative References
[I-D.ietf-nfsv4-versioning] [I-D.ietf-nfsv4-versioning]
Noveck, D., "Rules for NFSv4 Extensions and Minor Noveck, D., "Rules for NFSv4 Extensions and Minor
Versions", draft-ietf-nfsv4-versioning-09 (work in Versions", draft-ietf-nfsv4-versioning-09 (work in
progress), December 2016. progress), December 2016.
[NSM] The Open Group, "Protocols for Interworking: XNFS, Version [NSM] The Open Group, "Protocols for Interworking: XNFS, Version
3W", February 1998. 3W", February 1998.
[RFC1094] Nowicki, B., "NFS: Network File System Protocol [RFC1094] Nowicki, B., "NFS: Network File System Protocol
specification", RFC 1094, DOI 10.17487/RFC1094, March specification", RFC 1094, DOI 10.17487/RFC1094, March
1989, <http://www.rfc-editor.org/info/rfc1094>. 1989, <http://www.rfc-editor.org/info/rfc1094>.
[RFC1813] Callaghan, B., Pawlowski, B., and P. Staubach, "NFS [RFC1813] Callaghan, B., Pawlowski, B., and P. Staubach, "NFS
Version 3 Protocol Specification", RFC 1813, Version 3 Protocol Specification", RFC 1813,
DOI 10.17487/RFC1813, June 1995, DOI 10.17487/RFC1813, June 1995,
<http://www.rfc-editor.org/info/rfc1813>. <http://www.rfc-editor.org/info/rfc1813>.
[RFC3232] Reynolds, J., Ed., "Assigned Numbers: RFC 1700 is Replaced
by an On-line Database", RFC 3232, DOI 10.17487/RFC3232,
January 2002, <http://www.rfc-editor.org/info/rfc3232>.
[RFC5040] Recio, R., Metzler, B., Culley, P., Hilland, J., and D. [RFC5040] Recio, R., Metzler, B., Culley, P., Hilland, J., and D.
Garcia, "A Remote Direct Memory Access Protocol Garcia, "A Remote Direct Memory Access Protocol
Specification", RFC 5040, DOI 10.17487/RFC5040, October Specification", RFC 5040, DOI 10.17487/RFC5040, October
2007, <http://www.rfc-editor.org/info/rfc5040>. 2007, <http://www.rfc-editor.org/info/rfc5040>.
[RFC5041] Shah, H., Pinkerton, J., Recio, R., and P. Culley, "Direct [RFC5041] Shah, H., Pinkerton, J., Recio, R., and P. Culley, "Direct
Data Placement over Reliable Transports", RFC 5041, Data Placement over Reliable Transports", RFC 5041,
DOI 10.17487/RFC5041, October 2007, DOI 10.17487/RFC5041, October 2007,
<http://www.rfc-editor.org/info/rfc5041>. <http://www.rfc-editor.org/info/rfc5041>.
[RFC5666] Talpey, T. and B. Callaghan, "Remote Direct Memory Access
Transport for Remote Procedure Call", RFC 5666,
DOI 10.17487/RFC5666, January 2010,
<http://www.rfc-editor.org/info/rfc5666>.
[RFC5667] Talpey, T. and B. Callaghan, "Network File System (NFS) [RFC5667] Talpey, T. and B. Callaghan, "Network File System (NFS)
Direct Data Placement", RFC 5667, DOI 10.17487/RFC5667, Direct Data Placement", RFC 5667, DOI 10.17487/RFC5667,
January 2010, <http://www.rfc-editor.org/info/rfc5667>. January 2010, <http://www.rfc-editor.org/info/rfc5667>.
Appendix A. Changes Since RFC 5667 Appendix A. Changes Since RFC 5667
Corrections and updates made necessary by new language in Corrections and updates made necessary by new language in
[I-D.ietf-nfsv4-rfc5666bis] have been introduced. For example, [I-D.ietf-nfsv4-rfc5666bis] have been introduced. For example,
references to deprecated features of RPC-over-RDMA Version One, such references to deprecated features of RPC-over-RDMA Version One, such
as RDMA_MSGP, and the use of the Read list for handling RPC replies, as RDMA_MSGP, and the use of the Read list for handling RPC replies,
skipping to change at page 16, line 4 skipping to change at page 17, line 42
Some material that duplicates what is in [I-D.ietf-nfsv4-rfc5666bis] Some material that duplicates what is in [I-D.ietf-nfsv4-rfc5666bis]
has been deleted. has been deleted.
Material required by [I-D.ietf-nfsv4-rfc5666bis] for Upper Layer Material required by [I-D.ietf-nfsv4-rfc5666bis] for Upper Layer
Bindings that was not present in [RFC5667] has been added, including Bindings that was not present in [RFC5667] has been added, including
discussion of how each NFS version properly estimates the maximum discussion of how each NFS version properly estimates the maximum
size of RPC replies. size of RPC replies.
Technical corrections have been made. For example, the mention of Technical corrections have been made. For example, the mention of
12KB and 36KB inline thresholds have been removed. The reference to 12KB and 36KB inline thresholds have been removed. The reference to
a non-existant NFS version 4 SYMLINK operation has been replaced with a non-existant NFS version 4 SYMLINK operation has been replaced.
NFS version 4 CREATE(NF4LNK).
The discussion of NFS version 4 COMPOUND handling has been completed. The discussion of NFS version 4 COMPOUND handling has been completed.
Some changes were made to the algorithm for matching DDP-eligible Some changes were made to the algorithm for matching DDP-eligible
results to Write chunks. results to Write chunks.
Requirements to ignore extra Read or Write chunks have been removed Requirements to ignore extra Read or Write chunks have been removed
from the NFS version 2 and 3 Upper Layer Binding, as they conflict from the NFS version 2 and 3 Upper Layer Binding, as they conflict
with [I-D.ietf-nfsv4-rfc5666bis]. with [I-D.ietf-nfsv4-rfc5666bis].
A complete discussion of reply size estimation has been introduced A complete discussion of reply size estimation has been introduced
skipping to change at page 16, line 36 skipping to change at page 18, line 26
backchannel operation has replaced the previous treatment of backchannel operation has replaced the previous treatment of
callback operations. callback operations.
o A binding for NFS version 4.2 has been added that includes o A binding for NFS version 4.2 has been added that includes
discussion of new data-bearing operations like READ_PLUS. discussion of new data-bearing operations like READ_PLUS.
o A section suggesting a mechanism for periodically assessing o A section suggesting a mechanism for periodically assessing
connection health has been introduced. connection health has been introduced.
o Language inconsistent with or contradictory to o Language inconsistent with or contradictory to
[I-D.ietf-nfsv4-rfc5666bis] has been removed from Sections 2 and [I-D.ietf-nfsv4-rfc5666bis] has been removed from the present
3, and both Sections have been combined into Section 2 in the document.
present document.
o Ambiguous or erroneous uses of RFC2119 terms have been corrected. o Ambiguous or erroneous uses of RFC2119 terms have been corrected.
o References to obsolete RFCs have been updated. o References to obsolete RFCs have been updated.
o An IANA Considerations Section has replaced the "Port Usage o An IANA Considerations Section has been added, which specifies the
Considerations" Section. port assignments for NFS/RDMA. This replaces the example
assignment that appeared in [RFC5666].
o Code excerpts have been removed, and figures have been modernized. o Code excerpts have been removed, and figures have been modernized.
Appendix B. Acknowledgments Appendix B. Acknowledgments
The author gratefully acknowledges the work of Brent Callaghan and The author gratefully acknowledges the work of Brent Callaghan and
Tom Talpey on the original NFS Direct Data Placement specification Tom Talpey on the original NFS Direct Data Placement specification
[RFC5667]. The author also wishes to thank Bill Baker and Greg [RFC5667]. The author also wishes to thank Bill Baker and Greg
Marsden for their support of this work. Marsden for their support of this work.
Dave Noveck provided excellent review, constructive suggestions, and Dave Noveck provided excellent review, constructive suggestions, and
consistent navigational guidance throughout the process of drafting consistent navigational guidance throughout the process of drafting
this document. Dave also contributed the text of Section 4.5 this document. Dave also contributed the text of Section 5.6 and
Section 6, and insisted on precise discussion of reply size
estimation.
Thanks to Karen Deitke for her sharp observations about idempotency, Thanks to Karen Deitke for her sharp observations about idempotency,
and the clarity of the discussion of NFS COMPOUNDs and NFS sessions. and the clarity of the discussion of NFS COMPOUNDs and NFS sessions.
Special thanks go to Transport Area Director Spencer Dawkins, nfsv4 Special thanks go to Transport Area Director Spencer Dawkins, nfsv4
Working Group Chair Spencer Shepler, and nfsv4 Working Group Working Group Chair Spencer Shepler, and nfsv4 Working Group
Secretary Thomas Haynes for their support. Secretary Thomas Haynes for their support.
Author's Address Author's Address
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