< draft-ietf-nfsv4-rfc5667bis-06.txt   draft-ietf-nfsv4-rfc5667bis-07.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 24, 2017 Obsoletes: 5667 (if approved) March 9, 2017
Intended status: Standards Track Intended status: Standards Track
Expires: August 28, 2017 Expires: September 10, 2017
Network File System (NFS) Upper Layer Binding To RPC-Over-RDMA Version Network File System (NFS) Upper Layer Binding To RPC-Over-RDMA Version
One One
draft-ietf-nfsv4-rfc5667bis-06 draft-ietf-nfsv4-rfc5667bis-07
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 Version One. Upper Layer (NFS) protocol versions to RPC-over-RDMA Version One, enabling the
Bindings are required in order to enable RPC-based protocols such as use of Direct Data Placement. 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
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 28, 2017. This Internet-Draft will expire on September 10, 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.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Reply Size Estimation . . . . . . . . . . . . . . . . . . . . 3 2. Reply Size Estimation . . . . . . . . . . . . . . . . . . . . 3
2.1. Short Reply Chunk Retry . . . . . . . . . . . . . . . . . 4 2.1. Short Reply Chunk Retry . . . . . . . . . . . . . . . . . 4
3. Upper Layer Binding for NFS Versions 2 and 3 . . . . . . . . 5 3. Upper Layer Binding for NFS Versions 2 and 3 . . . . . . . . 5
3.1. Reply Size Estimation . . . . . . . . . . . . . . . . . . 5 3.1. Reply Size Estimation . . . . . . . . . . . . . . . . . . 5
3.2. RPC Binding Considerations . . . . . . . . . . . . . . . 5 3.2. RPC Binding Considerations . . . . . . . . . . . . . . . 5
4. Upper Layer Bindings for NFS Version 2 and 3 Auxiliary 4. Upper Layer Bindings for NFS Version 2 and 3 Auxiliary
Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.1. MOUNT, NLM, and NSM Protocols . . . . . . . . . . . . . . 6 4.1. MOUNT, NLM, and NSM Protocols . . . . . . . . . . . . . . 6
4.2. NFSACL Protocol . . . . . . . . . . . . . . . . . . . . . 7 4.2. NFSACL Protocol . . . . . . . . . . . . . . . . . . . . . 6
5. Upper Layer Binding For NFS Version 4 . . . . . . . . . . . . 7 5. Upper Layer Binding For NFS Version 4 . . . . . . . . . . . . 7
5.1. DDP-Eligibility . . . . . . . . . . . . . . . . . . . . . 7 5.1. DDP-Eligibility . . . . . . . . . . . . . . . . . . . . . 7
5.2. Reply Size Estimation . . . . . . . . . . . . . . . . . . 8 5.2. Reply Size Estimation . . . . . . . . . . . . . . . . . . 8
5.3. RPC Binding Considerations . . . . . . . . . . . . . . . 9 5.3. RPC Binding Considerations . . . . . . . . . . . . . . . 9
5.4. NFS COMPOUND Requests . . . . . . . . . . . . . . . . . . 10 5.4. NFS COMPOUND Requests . . . . . . . . . . . . . . . . . . 10
5.5. NFS Callback Requests . . . . . . . . . . . . . . . . . . 11 5.5. NFS Callback Requests . . . . . . . . . . . . . . . . . . 11
5.6. Session-Related Considerations . . . . . . . . . . . . . 12 5.6. Session-Related Considerations . . . . . . . . . . . . . 12
5.7. Transport Considerations . . . . . . . . . . . . . . . . 13 5.7. Transport Considerations . . . . . . . . . . . . . . . . 13
6. Extending NFS Upper Layer Bindings . . . . . . . . . . . . . 14 6. Extending NFS Upper Layer Bindings . . . . . . . . . . . . . 14
7. Security Considerations . . . . . . . . . . . . . . . . . . . 14 7. Security Considerations . . . . . . . . . . . . . . . . . . . 14
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 15 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.1. Normative References . . . . . . . . . . . . . . . . . . 15 9.1. Normative References . . . . . . . . . . . . . . . . . . 15
9.2. Informative References . . . . . . . . . . . . . . . . . 16 9.2. Informative References . . . . . . . . . . . . . . . . . 16
Appendix A. Changes Since RFC 5667 . . . . . . . . . . . . . . . 17 Appendix A. Changes Since RFC 5667 . . . . . . . . . . . . . . . 17
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 18 Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 18
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 19 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction 1. Introduction
An RPC-over-RDMA Version One transport may employ direct data The RPC-over-RDMA Version One transport may employ direct data
placement to convey certain data payloads associated with RPC placement to convey data payloads associated with RPC transactions
transactions [I-D.ietf-nfsv4-rfc5666bis]. To enable successful [I-D.ietf-nfsv4-rfc5666bis]. To enable successful interoperation,
interoperation, implementations of RPC Programs running on RPC-over- RPC client and server implementations using RPC-over-RDMA Version One
RDMA must agree as to which XDR data items in what particular RPC must agree which XDR data items and RPC procedures are eligible to
procedures are eligible for direct data placement (DDP). This use direct data placement (DDP).
agreement is specified in an Upper Layer Binding.
An Upper Layer Binding specifies this agreement for one RPC Program.
Other operational details, such as RPC binding assignments, pairing
Write chunks with result data items, and reply size estimation, are
also specified by this 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 are also provided for auxiliary protocols used
with NFS versions 2 and 3.
This document assumes the reader is already familiar with concepts This document assumes the reader is already familiar with concepts
and terminology defined in [I-D.ietf-nfsv4-rfc5666bis] and the and terminology defined in [I-D.ietf-nfsv4-rfc5666bis] and the
documents it references. documents it references.
2. Reply Size Estimation 2. Reply Size Estimation
On an RPC-over-RDMA Version One transport, during the construction of During the construction of each RPC Call message, a requester is
each RPC Call message, a requester is responsible for allocating responsible for allocating appropriate resources for receiving the
appropriate resources for receiving the matching Reply message. corresponding Reply message. If the requester expects the RPC Reply
message will be larger than its inline threshold, it provides Write
and/or Reply chunks wherein the responder can place results and the
reply's Payload stream.
An overrun of these resources can result in corruption of the Reply A reply resource overrun occurs if the RPC Reply Payload stream does
message or termination of the transport connection. Therefore not fit into the provided Reply chunk, or no Reply chunk was provided
reliable reply size estimation is necessary to ensure successful and the Payload stream does not fit inline. This prevents the
interoperation. This is particularly critical, for example, when responder from returning the Upper Layer reply to the requester.
allocating a Reply chunk.
Therefore reliable reply size estimation is necessary to ensure
successful interoperation.
In most cases, the NFS protocol's XDR definition provides enough In most cases, the NFS protocol's XDR definition provides enough
information to enable an NFS client to predict the maximum size 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 expected Reply message. If there are variable-size data items in
the result, the maximum size of the RPC Reply message can be the result, the maximum size of the RPC Reply message can be
estimated as follows: estimated as follows:
o The client requests only a specific portion of an object (for o The client requests only a specific portion of an object (for
example, using the "count" and "offset" fields in an NFS READ). example, using the "count" and "offset" fields in an NFS READ).
o The client limits the number of results (e.g. using the "count"
field of an NFS READDIR request).
o The client has already cached the size of the whole object it is o The client has already cached the size of the whole object it is
about to request (say, via a previous NFS GETATTR request). about to request (say, via a previous NFS GETATTR request).
o The client and server have negotiated a maximum size for all calls o The client and server have negotiated a maximum size for all calls
and responses (using a CREATE_SESSION operation, for instance). and responses (using a CREATE_SESSION operation, for instance).
2.1. Short Reply Chunk Retry 2.1. Short Reply Chunk Retry
In a few cases, either the size of one or more returned data items or In a few cases, either the size of one or more returned data items or
the number of returned data items cannot be known in advance of the number of returned data items cannot be known in advance of
forming an RPC Call. forming an RPC Call.
A requester uses a Reply chunk to handle an RPC transaction where the If an NFS server finds that the NFS client provided inadequate
expected RPC Reply message might be larger than the requester's receive resources to return the whole reply, it returns an RPC level
inline threshold. If an actual RPC Reply message does not fit in a error or a transport error, such as ERR_CHUNK.
client-provided Reply chunk, the NFS server responds with an
RDMA_ERROR message with the rdma_err field set to ERR_CHUNK, or it
could even break the transport connection.
In response, an NFS client can choose to: In response to these errors, an NFS client can choose to:
o Terminate the RPC transaction with an error, or o Terminate the RPC transaction immediately with an error, or
o Allocate a larger Reply chunk and send the same request as a new o Allocate a larger Reply chunk and send the same request as a new
RPC transaction (to avoid hitting in a Duplicate Reply Cache). RPC transaction (to avoid hitting in a Duplicate Reply Cache).
The NFS client should avoid retrying the request indefinitely The NFS client should avoid retrying the request indefinitely
because a responder may return ERR_CHUNK for a variety of reasons. because a responder may return ERR_CHUNK for a variety of reasons.
The latter choice is considered heroic recovery, and is only a real
choice for the few operations where it is not possible for an NFS
client to predict the size of the Reply message in advance.
Subsequent sections of this document discuss exactly which operations Subsequent sections of this document discuss exactly which operations
might have ultimate difficulty with Reply size estimation. These might have ultimate difficulty with Reply size estimation. These
operations are eligible for "short Reply chunk retry." Unless operations are eligible for "short Reply chunk retry." Unless
explicitly mentioned as applicable, short Reply chunk retry should explicitly mentioned as applicable, short Reply chunk retry should
not be used. not be used.
NFS server implementations can avoid connection loss by first
confirming that target RDMA segments are large enough to receive
results before initiating explicit RDMA operations.
3. Upper Layer Binding for NFS Versions 2 and 3 3. Upper Layer Binding for NFS Versions 2 and 3
The Upper Layer Binding specification in this section applies to NFS The Upper Layer Binding specification in this section applies to NFS
Version 2 [RFC1094] and NFS Version 3 [RFC1813]. For brevity, in Version 2 [RFC1094] and NFS Version 3 [RFC1813]. For brevity, in
this document a "Legacy NFS client" refers to an NFS client using the this document a "Legacy NFS client" refers to an NFS client using the
NFS version 2 or NFS version 3 RPC Programs (100003) to communicate 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 with an NFS server. Likewise, a "Legacy NFS server" is an NFS server
communicating with clients using NFS version 2 or NFS version 3. 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-
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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 NFS client MUST NOT send a reduced Payload stream in a Long A transport error does not give an indication of whether the server
Call. A Legacy NFS client MUST NOT enable a Legacy NFS server to has processed the arguments of the RPC Call, or whether the server
send a reduced Payload stream in a Long Reply. has accessed or modified client memory associated with that RPC.
A Legacy server's response to a DDP-eligibility violation does not
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. Reply Size Estimation 3.1. Reply Size Estimation
A Legacy NFS client determines the maximum reply size for each A Legacy NFS client determines the maximum reply size for each
operation using the criteria outlined in Section 2. There are no operation using the criteria outlined in Section 2. There are no
operations in NFS version 2 or 3 that benefit from short Reply chunk operations in NFS version 2 or 3 that benefit from short Reply chunk
retry. retry.
3.2. RPC Binding Considerations 3.2. RPC Binding Considerations
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[I-D.ietf-nfsv4-rfc5666bis]. [I-D.ietf-nfsv4-rfc5666bis].
4. Upper Layer Bindings for NFS Version 2 and 3 Auxiliary Protocols 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 distinct 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. The Upper Layer of the NFS version 2 or version 3 RPC Programs. The Upper Layer
Bindings in this section apply to: Bindings in this section apply to:
o The MOUNT and NLM protocols, introduced in an appendix of o Versions 2 and 3 of the MOUNT protocol [RFC1813]
[RFC1813]
o The NSM protocol, described in Chapter 11 of [NSM] o Versions 1, 3, and 4 of the NLM protocol [RFC1813]
o The NFSACL protocol, which does not have a public definition. o Version 1 of the NSM protocol, described in Chapter 11 of [XNFS]
NFSACL is treated in this document as a de facto standard, as
there are several interoperating implementations.
RPC-over-RDMA Version One considers these RPC Programs as separate o Version 1 of the NFSACL protocol, which does not have a public
Upper Layer Protocols [I-D.ietf-nfsv4-rfc5666bis]. Therefore a definition. NFSACL is treated in this document as a de facto
separate Upper Layer Binding, provided here, is required for each of standard, as there are several interoperating implementations.
these.
4.1. 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 the NFS RPC Program operates on RPC-over-RDMA deployments where the NFS RPC Program operates on RPC-over-RDMA
Version One. When a Legacy server supports these RPC Programs on Version One.
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 XDR data item in these protocols is DDP-eligible, therefore a
and the size of RPC messages in these protocols is uniformly small. special port assignment for operation on RPC-over-RDMA is not
Therefore, no XDR data items in these protocols are DDP-eligible. necessary. When a Legacy server supports these RPC Programs on RPC-
over-RDMA Version One, it advertises an arbitrarily-chosen service
port address via the rpcbind service [RFC1833].
The largest variable-length XDR data item is an xdr_netobj. In most The largest variable-length XDR data items in these protocols is
implementations this data item is never larger than 1024 bytes, defined in [XNFS]: LM_MAXSTRLEN is 1024 bytes, LM_MAXNAMELEN is
making reliable reply size estimation straightforward using the LM_MAXSTRLEN + 1, and MAXNETOBJ_SZ is 1024 bytes. Reply size
criteria outlined in Section 2. There are no operations in these estimation for these protocols uses the criteria outlined in
protocols that benefit from short Reply chunk retry. Section 2. There are no operations in these protocols that benefit
from short Reply chunk retry.
4.2. 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 NFS RPC typically convey NFSACL procedures on the same connection as NFS RPC
Programs. 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
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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,
5.2.1. Reply Size Estimation for Minor Version 0 5.2.1. Reply Size Estimation for Minor Version 0
The NFS version 4.0 protocol itself does not impose any bound on the The NFS version 4.0 protocol itself does not impose any bound on the
size of NFS calls or responses. size of NFS calls or responses.
Some of the data items enumerated in Section 5.2 (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 NFS version 4.0 replies that interrogate the maximum size of NFS version 4.0 replies that interrogate
variable-length fattr4 attributes. As discussed in Section 2, client variable-length fattr4 attributes. Client implementations might rely
implementations can rely on their own internal architectural limits on their own internal architectural limits to constrain the reply
to constrain the reply size, but such limits are not always size, but such limits are not always guaranteed to be reliable.
guaranteed to be reliable.
When an especially large fattr4 result is expected, a Reply chunk When an especially large fattr4 result is expected, a Reply chunk
might be required. An NFS version 4.0 client can use short Reply might be required. An NFS version 4.0 client can use short Reply
chunk retry when an NFS COMPOUND containing a GETATTR operation chunk retry when an NFS COMPOUND containing a GETATTR operation
encounters a transport error. 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 (e.g. WRITE) with a GETATTR that combine a non-idempotent operation (e.g. RENAME) with a GETATTR
operation that requests one or more variable-length results. This operation that requests one or more variable-length results. This
combination should be avoided by ensuring that any GETATTR operation combination should be avoided by ensuring that any GETATTR operation
that requests a result of unpredictable length is sent in an NFS that requests a result of unpredictable length is sent in an NFS
COMPOUND by itself. COMPOUND by itself.
5.2.2. 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
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they are not required to register with an rpcbind service [RFC7530]. they are not required to register with an rpcbind service [RFC7530].
Therefore, an NFS version 4 server supporting RPC-over-RDMA Version Therefore, an NFS version 4 server supporting RPC-over-RDMA Version
One MUST use the alternative well-known port number for its RPC-over- One MUST use the alternative well-known port number for its RPC-over-
RDMA service (see Section 8). Clients SHOULD connect to this well- RDMA service (see Section 8). Clients SHOULD connect to this well-
known port without consulting the RPC portmapper (as for NFS version known port without consulting the RPC portmapper (as for NFS version
4 on TCP transports). 4 on TCP transports).
5.4. NFS COMPOUND Requests 5.4. NFS COMPOUND Requests
5.4.1. Long Calls and Replies 5.4.1. Multiple DDP-eligible Data Items
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 An NFS version 4 COMPOUND procedure can contain more than one
than one DDP-eligible data item per Call and Reply message. An NFS operation that carries a DDP-eligible data item. An NFS version 4
version 4 client provides XDR Position values in each Read chunk to 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
[I-D.ietf-nfsv4-rfc5666bis]) is applied here, with additional
restrictions that appear below.
In the following list, an "NFS Read" operation refers to any NFS In the following list, an "NFS Read" operation refers to any NFS
Version 4 operation which has a DDP-eligible result data item (i.e., Version 4 operation which has a DDP-eligible result data item (i.e.,
either a READ, READ_PLUS, or READLINK operation). either a READ, READ_PLUS, or READLINK operation). The mechanism
specified in Section 4.3.2 of [I-D.ietf-nfsv4-rfc5666bis]) is applied
to this class of operations:
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-
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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.
5.4.3. NFS Version 4 COMPOUND Example 5.4.2. 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 12, line 18 skipping to change at page 11, line 49
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.
5.5.2. 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 approach described in [I-D.ietf-nfsv4-rpcrdma-bidirection] when
backchannel operations are conveyed on RPC-over-RDMA Version One backchannel operations are conveyed on RPC-over-RDMA Version One
transports. 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
skipping to change at page 13, line 31 skipping to change at page 13, line 17
5.7.1. Congestion Avoidance 5.7.1. Congestion Avoidance
Section 3.1 of [RFC7530] states: Section 3.1 of [RFC7530] states:
Where an NFSv4 implementation supports operation over the IP Where an NFSv4 implementation supports operation over the IP
network protocol, the supported transport layer between NFS and IP network protocol, the supported transport layer between NFS and IP
MUST be an IETF standardized transport protocol that is specified MUST be an IETF standardized transport protocol that is specified
to avoid network congestion; such transports include TCP and the to avoid network congestion; such transports include TCP and the
Stream Control Transmission Protocol (SCTP). Stream Control Transmission Protocol (SCTP).
Section 2.9.1 of [RFC5661] further states: Section 2.9.1 of [RFC5661] also states:
Even if NFSv4.1 is used over a non-IP network protocol, it is Even if NFSv4.1 is used over a non-IP network protocol, it is
RECOMMENDED that the transport support congestion control. RECOMMENDED that the transport support congestion control.
It is permissible for a connectionless transport to be used under It is permissible for a connectionless transport to be used under
NFSv4.1; however, reliable and in-order delivery of data combined NFSv4.1; however, reliable and in-order delivery of data combined
with congestion control by the connectionless transport is with congestion control by the connectionless transport is
REQUIRED. As a consequence, UDP by itself MUST NOT be used as an REQUIRED. As a consequence, UDP by itself MUST NOT be used as an
NFSv4.1 transport. NFSv4.1 transport.
skipping to change at page 15, line 44 skipping to change at page 15, line 32
[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-10 (work in progress), One", draft-ietf-nfsv4-rfc5666bis-10 (work in progress),
February 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-07 (work in progress), February 2017. bidirection-08 (work in progress), March 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>.
skipping to change at page 16, line 41 skipping to change at page 16, line 32
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>.
9.2. 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
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>.
[RFC5040] Recio, R., Metzler, B., Culley, P., Hilland, J., and D. [RFC5040] Recio, R., Metzler, B., Culley, P., Hilland, J., and D.
skipping to change at page 17, line 24 skipping to change at page 17, line 14
[RFC5666] Talpey, T. and B. Callaghan, "Remote Direct Memory Access [RFC5666] Talpey, T. and B. Callaghan, "Remote Direct Memory Access
Transport for Remote Procedure Call", RFC 5666, Transport for Remote Procedure Call", RFC 5666,
DOI 10.17487/RFC5666, January 2010, DOI 10.17487/RFC5666, January 2010,
<http://www.rfc-editor.org/info/rfc5666>. <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>.
[XNFS] The Open Group, "Protocols for Interworking: XNFS, Version
3W", February 1998.
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,
have been removed. The term "mapping" has been replaced with the have been removed. The term "mapping" has been replaced with the
term "binding" or "Upper Layer Binding" throughout the document. term "binding" or "Upper Layer Binding" throughout the document.
Some material that duplicates what is in [I-D.ietf-nfsv4-rfc5666bis] Material that duplicates what is in [I-D.ietf-nfsv4-rfc5666bis] has
has been deleted. 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. A
discussion of how each NFS version properly estimates the maximum complete discussion of reply size estimation has been introduced for
size of RPC replies. all protocols covered by the Upper Layer Bindings in this document.
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. a non-existant NFS version 4 SYMLINK operation has been replaced.
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
for all protocols covered by the Upper Layer Bindings in this
document.
A section discussing NFS version 4 retransmission and connection loss A section discussing NFS version 4 retransmission and connection loss
has been added. has been added.
The following additional improvements have been made, relative to The following additional improvements have been made, relative to
[RFC5667]: [RFC5667]:
o An explicit discussion of NFS version 4.0 and NFS version 4.1 o An explicit discussion of NFS version 4.0 and NFS version 4.1
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
[I-D.ietf-nfsv4-rfc5666bis] has been removed from the 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 been added, which specifies the o An IANA Considerations Section has been added, which specifies the
port assignments for NFS/RDMA. This replaces the example port assignments for NFS/RDMA. This replaces the example
assignment that appeared in [RFC5666]. 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.
 End of changes. 45 change blocks. 
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