< draft-ietf-nfsv4-rfc5667bis-02.txt   draft-ietf-nfsv4-rfc5667bis-03.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) August 25, 2016 Obsoletes: 5667 (if approved) September 28, 2016
Intended status: Standards Track Intended status: Standards Track
Expires: February 26, 2017 Expires: April 1, 2017
Network File System (NFS) Upper Layer Binding To RPC-Over-RDMA Network File System (NFS) Upper Layer Binding To RPC-Over-RDMA
draft-ietf-nfsv4-rfc5667bis-02 draft-ietf-nfsv4-rfc5667bis-03
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 transports. These bindings (NFS) protocol versions to RPC-over-RDMA transports. These bindings
are required to enable RPC-based protocols to use direct data are required to enable RPC-based protocols such as NFS to use direct
placement on RPC-over-RDMA transports. This document obsoletes RFC data placement on RPC-over-RDMA transports. This document obsoletes
5667. RFC 5667.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 February 26, 2017. This Internet-Draft will expire on April 1, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 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
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Changes Since RFC 5667 . . . . . . . . . . . . . . . . . 3 2. Conveying NFS Operations On RPC-Over-RDMA Transports . . . . 3
1.2. Extending This Upper Layer Binding . . . . . . . . . . . 4 3. NFS Versions 2 And 3 Upper Layer Binding . . . . . . . . . . 4
1.3. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Conveying NFS Operations On RPC-Over-RDMA Transports . . . . 4
2.1. Use Of The Read List . . . . . . . . . . . . . . . . . . 4
2.2. Use Of The Write List . . . . . . . . . . . . . . . . . . 4
2.3. Construction Of Individual Chunks . . . . . . . . . . . . 5
2.4. Use Of Long Calls And Replies . . . . . . . . . . . . . . 5
3. NFS Versions 2 And 3 Upper Layer Binding . . . . . . . . . . 5
4. NFS Version 4 Upper Layer Binding . . . . . . . . . . . . . . 6 4. NFS Version 4 Upper Layer Binding . . . . . . . . . . . . . . 6
4.1. DDP-Eligibility . . . . . . . . . . . . . . . . . . . . . 6 5. Extending NFS Upper Layer Bindings . . . . . . . . . . . . . 13
4.2. Reply Size Estimation . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
4.3. NFS Version 4 COMPOUND Considerations . . . . . . . . . . 7 7. Security Considerations . . . . . . . . . . . . . . . . . . . 13
4.4. NFS Version 4 Callback . . . . . . . . . . . . . . . . . 9 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 Appendix A. Changes Since RFC 5667 . . . . . . . . . . . . . . . 15
6. Security Considerations . . . . . . . . . . . . . . . . . . . 10 Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 16
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 17
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Normative References . . . . . . . . . . . . . . . . . . 10
8.2. Informative References . . . . . . . . . . . . . . . . . 11
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction 1. Introduction
An RPC-over-RDMA transport, such as defined in An RPC-over-RDMA transport, such as defined in
[I-D.ietf-nfsv4-rfc5666bis], may employ direct data placement to [I-D.ietf-nfsv4-rfc5666bis], may employ direct data placement to
transmit large data payloads associated with RPC transactions. Each convey data payloads associated with RPC transactions. Each RPC-
RPC-over-RDMA transport header conveys lists of memory locations over-RDMA transport header conveys lists of memory locations
corresponding to XDR data items defined in an Upper Layer Protocol corresponding to XDR data items defined in an Upper Layer Protocol
(such as NFS). (such as NFS).
To facilitate interoperation, RPC client and server implementations To facilitate interoperation, RPC client and server implementations
must agree in advance on what XDR data items in which RPC procedures must agree in advance on what XDR data items in which RPC procedures
are eligible for direct data placement (DDP). This document contains are eligible for direct data placement (DDP). This document contains
material required of Upper Layer Bindings, as specified in material required of Upper Layer Bindings, as specified in
[I-D.ietf-nfsv4-rfc5666bis], for the following NFS protocol versions: [I-D.ietf-nfsv4-rfc5666bis], for the following NFS protocol versions:
o NFS Version 2 [RFC1094] o NFS Version 2 [RFC1094]
skipping to change at page 3, line 4 skipping to change at page 2, line 46
must agree in advance on what XDR data items in which RPC procedures must agree in advance on what XDR data items in which RPC procedures
are eligible for direct data placement (DDP). This document contains are eligible for direct data placement (DDP). This document contains
material required of Upper Layer Bindings, as specified in material required of Upper Layer Bindings, as specified in
[I-D.ietf-nfsv4-rfc5666bis], for the following NFS protocol versions: [I-D.ietf-nfsv4-rfc5666bis], for the following NFS 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 [I-D.ietf-nfsv4-minorversion2] o NFS Version 4.2 [I-D.ietf-nfsv4-minorversion2]
1.1. Changes Since RFC 5667
Corrections and updates made necessary by new language in
[I-D.ietf-nfsv4-rfc5666bis] have been introduced. For example,
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,
has been removed. The term "mapping" has been replaced with the term
"binding" or "Upper Layer Binding" throughout the document. Material
that duplicates what is in [I-D.ietf-nfsv4-rfc5666bis] has been
deleted.
Material required by [I-D.ietf-nfsv4-rfc5666bis] for Upper Layer
Bindings that was not present in [RFC5667] has been added, including
discussion of how each NFS version properly estimates the maximum
size of RPC replies.
The following changes have been made, relative to [RFC5667]:
o Ambiguous or erroneous uses of RFC2119 terms have been corrected.
o References to specific data movement mechanisms have been made
generic or removed.
o References to obsolete RFCs have been replaced.
o Technical corrections have been made. For example, the mention of
12KB and 36KB inline thresholds have been removed. The reference
to a non-existant NFS version 4 SYMLINK operation has been
replaced with NFS version 4 CREATE(NF4LNK). The discussion of NFS
version 4 COMPOUND handling has been completed.
o An IANA Considerations Section has replaced the "Port Usage
Considerations" Section.
o Code excerpts have been removed, and figures have been modernized.
o Language inconsistent with or contradictory to
[I-D.ietf-nfsv4-rfc5666bis] has been removed from Sections 2 and
3, and both Sections have been combined into Section 2 in the
present document.
o An explicit discussion of NFSv4.0 and NFSv4.1 backchannel
operation will replace the previous treatment of callback
operations. No NFSv4.x callback operation is DDP-eligible.
o The binding for NFSv4.1 has been completed. No DDP-eligible
operations exist in NFSv4.1 that did not exist in NFSv4.0.
o A binding for NFSv4.2 has been added that includes discussion of
new data-bearing operations like READ_PLUS.
1.2. Extending This Upper Layer Binding
As stated earlier, RPC programs such as NFS are required to have an
Upper Layer Binding specification to interoperate on RPC-over-RDMA
transports [I-D.ietf-nfsv4-rfc5666bis]. The Upper Layer Binding
specified in this document can be extended to cover versions of the
NFS version 4 protocol specified after NFS version 4 minor version 2
via standards action. This includes NFSv4 extensions that are
documented separately from a new minor version.
1.3. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2. Conveying NFS Operations On RPC-Over-RDMA Transports 2. Conveying NFS Operations On RPC-Over-RDMA Transports
Definitions of terminology and a general discussion of how RPC-over- Definitions of terminology and a general discussion of how RPC-over-
RDMA is used to convey RPC transactions can be found in RDMA is used to convey RPC transactions can be found in
[I-D.ietf-nfsv4-rfc5666bis]. In this section, these general [I-D.ietf-nfsv4-rfc5666bis]. In this section, these general
principals are applied to the specifics of the NFS protocol. principals are applied to the specifics of the NFS protocol.
2.1. Use Of The Read List 2.1. Use Of The Read List
The Read list in each RPC-over-RDMA transport header represents a set The Read list in each RPC-over-RDMA transport header represents a set
of memory regions containing DDP-eligible NFS argument data. Large of memory regions containing DDP-eligible NFS argument data. Large
data items, such as the data payload of an NFS WRITE request, are data items, such as the data payload of an NFS version 3 WRITE
referenced by the Read list. The server places these directly into procedure, are referenced by the Read list. The NFS server pulls
its memory. such payloads from the client and places them directly into its own
memory.
XDR unmarshaling code on the NFS server identifies the correspondence XDR unmarshaling code on the NFS server identifies the correspondence
between Read chunks and particular NFS arguments via the chunk between Read chunks and particular NFS arguments via the chunk
Position value encoded in each Read chunk. Position value encoded in each Read segment.
2.2. Use Of The Write List 2.2. Use Of The Write List
The Write list in each RPC-over-RDMA transport header represents a The Write list in each RPC-over-RDMA transport header represents a
set of memory regions that can receive DDP-eligible NFS result data. set of memory regions that can receive DDP-eligible NFS result data.
Large data items such as the payload of an NFS READ request are Large data items, such as the payload of an NFS version 3 READ
referenced by the Write list. The server places these directly into procedure, are referenced by the Write list. The NFS server pushes
client memory. such payloads to the client, placing them directly into the client's
memory.
Each Write chunk corresponds to a specific XDR data item in an NFS Each Write chunk corresponds to a specific XDR data item in an NFS
reply. This document specifies how NFS client and server reply. This document specifies how NFS client and server
implementations identify the correspondence between Write chunks and implementations identify the correspondence between Write chunks and
XDR results. XDR results.
2.3. Construction Of Individual Chunks 2.2.1. Empty Write Chunks
Each Read chunk is represented as a list of segments at the same XDR Section 4.4.6.2 of [I-D.ietf-nfsv4-rfc5666bis] defines the concept of
Position, and each Write chunk is represented as an array of unused Write chunks. An unused Write chunk is a Write chunk with
segments. An NFS client thus has the flexibility to advertise a set either zero segments or where all segments in the Write chunk have
of discontiguous memory regions in which to send or receive a single zero length. In this document these are referred to as "empty" Write
DDP-eligible data item. chunks. A "non-empty" Write chunk has at least one segment of non-
zero length.
2.4. Use Of Long Calls And Replies An NFS client might wish an NFS server to return a DDP-eligible
result inline. If there is only one DDP-eligible result item in the
reply, the NFS client simply specifies an empty Write list to force
the NFS server to return that result inline. If there are multiple
DDP-eligible results, the NFS client specifies empty Write chunks for
each DDP-eligible data item that it wishes to be returned inline.
An NFS server might encounter an XDR union result where there are
arms that have a DDP-eligible result, and arms that do not. If the
NFS client has provided a non-empty Write chunk that matches with a
DDP-eligible result, but the response does not contain that result,
the NFS server MUST return an empty Write chunk in that position in
the Write list.
2.3. Use Of Long Calls And Replies
Small RPC messages are conveyed using RDMA Send operations which are Small RPC messages are conveyed using RDMA Send operations which are
of limited size. If an NFS request is too large to be conveyed via of limited size. If an NFS request is too large to be conveyed
an RDMA Send, and there are no DDP-eligible data items that can be within the NFS server's responder inline threshold, and there are no
removed, an NFS client must send the request using a Long Call. The DDP-eligible data items that can be removed, an NFS client must send
entire NFS request is sent in a special Read chunk called a Position- the request using a Long Call. The entire NFS request is sent in a
Zero Read chunk. special Read chunk called a Position-Zero Read chunk.
If a client predicts that the maximum size of an NFS reply is too If an NFS client predicts that the maximum size of an NFS reply could
large to be conveyed via an RDMA Send, it provides a Reply chunk in be too large to be conveyed within it's own responder inline
the RPC-over-RDMA transport header conveying the NFS request. The threshold, it provides a Reply chunk in the RPC-over-RDMA transport
server can place the entire NFS reply in the Reply chunk. header conveying the NFS request. The server places the entire NFS
reply in the Reply chunk.
These special chunks are described in more detail in These special chunks are described in more detail in
[I-D.ietf-nfsv4-rfc5666bis]. [I-D.ietf-nfsv4-rfc5666bis].
2.4. Scatter-Gather Considerations
A chunk comprises exactly one XDR data item. Each Read chunk is
represented as a list of segments at the same XDR Position. Each
Write chunk is represented as an array of segments. An NFS client
thus has the flexibility to advertise a set of discontiguous memory
regions in which to send or receive a single DDP-eligible XDR data
item.
3. NFS Versions 2 And 3 Upper Layer Binding 3. NFS Versions 2 And 3 Upper Layer Binding
An NFS client MAY send a single Read chunk to supply opaque file data An NFS version 2 or version 3 client MAY send a single Read chunk to
for an NFS WRITE procedure, or the pathname for an NFS SYMLINK supply the opaque file data for an NFS WRITE procedure, or the
procedure. For all other NFS procedures, NFS servers MUST ignore pathname for an NFS SYMLINK procedure. For these procedures, NFS
Read chunks that have a non-zero value in their Position fields, and version 2 or 3 servers MUST ignore Read chunks beyond the first in
Read chunks beyond the first in the Read list. the Read list. For all other NFS procedures, NFS version 2 or 3
servers MUST ignore Read chunks that have a non-zero value in their
Position fields.
Similarly, an NFS client MAY provide a single Write chunk to receive Similarly, an NFS version 2 or version 3 client MAY provide a single
either opaque file data from an NFS READ procedure, or the pathname Write chunk to receive either the opaque file data from an NFS READ
from an NFS READLINK procedure. NFS servers MUST ignore the Write procedure, or the pathname from an NFS READLINK procedure. For these
list for any other NFS procedure, and any Write chunks beyond the procedures, NFS version 2 or 3 servers MUST ignore Write chunks
first in the Write list. beyond the first in the Write list. For all other NFS procedures,
NFS version 2 or 3 servers MUST ignore the Write list.
There are no NFS version 2 or 3 procedures that have DDP-eligible There are no NFS version 2 or 3 procedures that have DDP-eligible
data items in both their Call and Reply. However, when an NFS client data items in both their Call and Reply. However, when an NFS
sends a Long Call or Reply, it MAY provide a combination of Read version 2 or version 3 client sends a Long Call or Reply, it MAY
list, Write list, and/or a Reply chunk in the same RPC-over-RDMA provide a combination of a Read list, a Write list, and/or a Reply
header. chunk in the same RPC-over-RDMA header.
If an NFS client has not provided enough bytes in a Read list to If an NFS version 2 or version 3 client has not provided enough bytes
match the size of a DDP-eligible NFS argument data item, or if an NFS in a Read list to match the size of a DDP-eligible NFS argument data
client has not provided enough Write list resources to handle an NFS item, or if an NFS version 2 or version 3 client has not provided
WRITE or READLINK reply, or if the client has not provided a large enough Write list resources to handle an NFS READ or READLINK reply,
enough Reply chunk to convey an NFS reply, the server MUST return one or if the client has not provided a large enough Reply chunk to
of: convey an NFS reply, the server MUST return one of:
o An RPC-over-RDMA message of type RDMA_ERROR, with the rdma_xid o An RPC-over-RDMA message of type RDMA_ERROR, with the rdma_xid
field set to the XID of the matching NFS Call, and the rdma_error field set to the XID of the matching NFS Call, and the rdma_error
field set to ERR_CHUNK; or field set to ERR_CHUNK; or
o An RPC message with the mtype field set to REPLY, the stat field o An RPC message (via an RDMA_MSG message) with the xid field set to
set to MSG_ACCEPTED, and the accept_stat field set to the XID of the matching NFS Call, the mtype field set to REPLY,
GARBAGE_ARGS. the stat field set to MSG_ACCEPTED, and the accept_stat field set
to GARBAGE_ARGS.
NFS clients already successfully estimate the maximum reply size of These replies do not give any indication to NFS version 2 or version
each operation in order to provide an adequate set of buffers to 3 clients of whether an NFS version 2 or 3 server has processed the
receive each NFS reply. An NFS client provides a Reply chunk when arguments of the RPC Call, or whether the NFS version 2 or 3 server
the maximum possible reply size is larger than the client's responder has accessed NFS client memory associated with that RPC.
inline threshold.
NFS version 2 or version 3 clients already successfully estimate the
maximum reply size of each operation in order to provide an adequate
set of buffers to receive each NFS reply. An NFS version 2 or
version 3 client provides a Reply chunk when the maximum possible
reply size is larger than the client's responder inline threshold.
3.1. Auxiliary Protocols
NFS versions 2 and 3 are typically deployed with several other
protocols, referred to as "auxiliary" protocols. These are separate
RPC protcols which handle operations that are not part of the main
NFS protocol. These include the MOUNT and NLM protocols, introduced
in an appendix of [RFC1813]; the NSM protocol, described in Chapter
11 of [NSM]; and the NFSACL protocol, which does not have a public
definition. However NFSACL is treated as a de facto standard and
there are several interoperating implementations.
RPC-over-RDMA considers these as individual Upper Layer Protocols
[I-D.ietf-nfsv4-rfc5666bis]. Therefore to operate on an RPC-over-
RDMA transport, an Upper Layer Binding must be provided for each of
these.
Typically MOUNT, NLM, and NSM are conveyed via TCP rather than RPC-
over-RDMA. Note that only metadata is conveyed in these protocols,
thus direct data placement is never necessary, and the size of RPC
messages is uniformly small. The maximum size of replies is easily
determined by examining the XDR definitions of these protocols.
Implementations that support the NFSACL protocol typically send
NFSACL procedures on the same connection as the main NFS protocol.
Thus NFSACL does require an Upper Layer Binding.
No data item in this protocol is DDP-eligible. There is no protocol
size limit for NFS version 3 ACL objects. The client can have some
difficulty ascertaining the size of ACLs to be read from servers.
Practically speaking, ACLs are not large (less than 4KB in most
cases), but a large Reply chunk may be provided when the client is in
doubt. The usual rules apply to the use of Long Messages when the
size of an NFSACL RPC exceeds a connection's inline thresholds.
4. NFS Version 4 Upper Layer Binding 4. NFS Version 4 Upper Layer Binding
This specification applies to NFS Version 4.0 [RFC7530], NFS Version This specification applies to NFS Version 4.0 [RFC7530], NFS Version
4.1 [RFC5661], and NFS Version 4.2 [I-D.ietf-nfsv4-minorversion2]. 4.1 [RFC5661], and NFS Version 4.2 [I-D.ietf-nfsv4-minorversion2].
It also applies to the callback protocols associated with each of It also applies to the callback protocols associated with each of
these minor versions. these minor versions defined in the same documents.
4.1. DDP-Eligibility 4.1. DDP-Eligibility
An NFS client MAY send a Read chunk to supply opaque file data for a For each WRITE operation in an NFS version 4 COMPOUND procedure, an
WRITE operation or the pathname for a CREATE(NF4LNK) operation in an NFS version 4 client MAY provide a single Read chunk to supply the
NFS version 4 COMPOUND procedure. An NFS client MUST NOT send a Read opaque file data argument. For each CREATE(NF4LNK) operation in an
chunk that corresponds with any other XDR data item in any other NFS NFS version 4 COMPOUND procedure, An NFS version 4 client MAY provide
version 4 operation in an NFS version 4 COMPOUND procedure, or in an a single Read chunk to supply the pathname argument.
NFS version 4 NULL procedure.
Similarly, an NFS client MAY provide a Write chunk to receive either Similarly, for each READ operation in an NFS version 4 COMPOUND
opaque file data from a READ operation, NFS4_CONTENT_DATA from a procedure, an NFS version 4 client MAY provide a single Write chunk
READ_PLUS operation, or the pathname from a READLINK operation in an to receive the opaque file data argument. For each READ_PLUS
NFS version 4 COMPOUND procedure. An NFS client MUST NOT provide a operation in an NFS version 4 COMPOUND procedure, an NFS version 4
Write chunk that corresponds with any other XDR data item in any client MAY provide a single Write chunk to receive NFS4_CONTENT_DATA.
other NFS version 4 operation in an NFS version 4 COMPOUND procedure, For each READLINK operation in an NFS version 4 COMPOUND procedure,
or in an NFS version 4 NULL procedure. an NFS version 4 client MAY provide a single Write chunk to receive
the pathname argument.
There is no prohibition against an NFS version 4 COMPOUND procedure An NFS version 4 client MUST NOT provide a Read or Write chunk that
constructed with both a READ and WRITE operation, say. Thus it is corresponds with any other XDR data item in any other NFS version 4
possible for NFS version 4 COMPOUND procedures to use both the Read operation in an NFS version 4 COMPOUND procedure, or in an NFS
list and Write list simultaneously. An NFS client MAY provide a Read version 4 NULL procedure.
list and a Write list in the same transaction if it is sending a Long
Call or Reply.
If an NFS client has not provided enough bytes in a Read list to It is possible for NFS version 4 COMPOUND procedures to use both the
match the size of a DDP-eligible NFS argument data item, or if an NFS Read list and Write list simultaneously. An NFS version 4 client MAY
client has not provided enough Write list resources to handle a WRITE provide a Read list and a Write list in the same transaction if it is
or READLINK operation, or if the client has not provided a large sending a Long Call or Reply.
enough Reply chunk to convey an NFS reply, the server MUST return one
of: If an NFS version 4 client has not provided enough bytes in a Read
list to match the size of a DDP-eligible NFS argument data item, or
if an NFS version 4 client has not provided enough Write list
resources to handle a WRITE or READLINK operation, or if the client
has not provided a large enough Reply chunk to convey an NFS reply,
the server MUST return one of:
o An RPC-over-RDMA message of type RDMA_ERROR, with the rdma_xid o An RPC-over-RDMA message of type RDMA_ERROR, with the rdma_xid
field set to the XID of the matching NFS Call, and the rdma_error field set to the XID of the matching NFS Call, and the rdma_error
field set to ERR_CHUNK; or field set to ERR_CHUNK; or
o An RPC message with the mtype field set to REPLY, the stat field o An RPC message (via an RDMA_MSG message) with the xid field set to
set to MSG_ACCEPTED, and the accept_stat field set to the XID of the matching NFS Call, the stat field set to
GARBAGE_ARGS. MSG_ACCEPTED, and the accept_stat field set to GARBAGE_ARGS.
Such error replies are permanent errors, and constitute both
completion of the RPC transaction, and a valid server response. It
is not necessary for an NFS version 4 server to drop the transport
connection in this case.
4.1.1. Session-Related Considerations
In most cases, the presence of an NFS session [RFC5661] has no effect
on the operation of RPC-over-RDMA. None of the operations introduced
to support NFS sessions contain DDP-eligible data items. There is no
need to match the number of session slots with the number of
available RPC-over-RDMA credits.
However, there are some rare error conditions which require special
handling when an NFS session is operating on an RPC-over-RDMA
transport. For example, a requester might receive, in response to an
RPC request, an RDMA_ERROR message with an rdma_err value of
ERR_CHUNK, or an RDMA_MSG containing an RPC_GARBAGEARGS reply.
Within RPC-over-RDMA Version One, this class of error can be
generated for two different reasons:
o There was an XDR error detected parsing the RPC-over-RDMA headers.
o There was an error sending the response, because, for example, a
necessary reply chunk was not provided or the one provided is of
insufficient length.
These two situations, which arise only due to incorrect
implementations, have different implications with regard to Exactly-
Once Semantics. An XDR error in decoding the request precludes the
execution of the request on the responder, but failure to send a
reply indicates that some or all of the operations were executed.
In both instances, the client SHOULD NOT retry the operation. A
retry is liable to result in the same sort of error seen previously.
Instead, it is best to consider the operation as completed
unsuccessfully and report an error to the consumer who requested the
RPC.
In addition, within the error response, the requester does not have
the result of the execution of the SEQUENCE operation, which
identifies the session, slot, and sequence id for the request which
has failed. The xid associated with the request, obtained from the
rdma_xid field of the RDMA_ERROR or RDMA_MSG message, must be used to
determine the session and slot for the request which failed, and the
slot must be properly retired. If this is not done, the slot could
be rendered permanently unavailable.
4.2. Reply Size Estimation 4.2. Reply Size Estimation
An NFS client provides a Reply chunk when the maximum possible reply An NFS version 4 client provides a Reply chunk when the maximum
size is larger than the client's responder inline threshold. NFS possible reply size is larger than the client's responder inline
clients successfully estimate the maximum reply size of most threshold. NFS version 4 clients already successfully estimate the
operations in order to provide an adequate set of buffers to receive maximum reply size of most operations in order to provide an adequate
each NFS reply. set of buffers to receive each NFS reply.
There are certain NFSv4 data items whose size cannot be reliably There are certain NFS version 4 data items whose size cannot be
estimated by clients, however, because there is no protocol-specified estimated by clients reliably, however, because there is no protocol-
size limit on these structures. These include but are not limited to specified size limit on these structures. These include but are not
opaque types such as the attrlist4 field; fields containing ACLs such limited to opaque types, such as:
as fattr4_acl, fattr4_dacl, fattr4_sacl; fields in the fs_locations4
and fs_locations_info4 data structures; and opaque fields loc_body,
loh_body, da_addr_body, lou_body, lrf_body, fattr_layout_types and
fs_layout_types, which pertain to pNFS layout metadata.
4.3. NFS Version 4 COMPOUND Considerations o The attrlist4 field
An NFS version 4 COMPOUND procedure supplies arguments for a sequence o Fields containing ACLs such as fattr4_acl, fattr4_dacl,
of operations, and returns results from that sequence. A client MAY fattr4_sacl
construct an NFS version 4 COMPOUND procedure that uses more than one
chunk in either the Read list or Write list. The NFS client provides
XDR Position values in each Read chunk to disambiguate which chunk is
associated with which XDR data item.
However NFS server and client implementations must agree in advance o Fields in the fs_locations4 and fs_locations_info4 data structures
on how to pair Write chunks with returned result data items. The o Opaque fields which pertain to pNFS layout metadata, such as
mechanism specified in [I-D.ietf-nfsv4-rfc5666bis]) is applied here: loc_body, loh_body, da_addr_body, lou_body, lrf_body,
fattr_layout_types and fs_layout_types,
o The first chunk in the Write list MUST be used by the first READ In NFS version 4.1 and later minor versions, the csa_fore_chan_attrs
or READLINK operation in an NFS version 4 COMPOUND procedure. The argument of the CREATE_SESSION operation contains a
next Write chunk is used by the next READ or READLINK, and so on. ca_maxresponsesize field. The value in this field can be taken as
the absolute maximum size of replies generated by a replying NFS
version 4 server. 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 ACLs, named attributes, layout bodies, and
security labels are much smaller than this maximum.
o If there are more READ or READLINK operations than Write chunks, With regard to NFS version 4.0, things are more troublesome.
then any remaining operations MUST return their results inline. Typically NFS version 4.0 client implementations rely on their own
architectural limits to keep reply buffer sizes reasonable. For
instance, although the NFS version 4 protocol is capable of conveying
a megabyte-sized ACL, nearly all known physical filesystems store
ACLs in on-disk containers which are small in size.
o If an NFS client presents a Write chunk, then the corresponding 4.2.1. Managing READ_PLUS Replies
READ or READLINK operation MUST return its data by placing data
into that chunk.
o If the Write chunk has zero RDMA segments, or if the total size of The NFS version 4.2 READ_PLUS operation returns a complex data type
the segments is zero, then the corresponding READ or READLINK [I-D.ietf-nfsv4-minorversion2]. The rpr_contents field in the result
operation MUST return its result inline. of this operation is an array of read_plus_content unions, one arm of
which contains an opaque byte stream (d_data).
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
returned in the rpr_contents array. In order to make the size of
READ_PLUS replies predictable by NFS version 4.2 clients, the
following restrictions are placed on the use of the READ_PLUS
operation on RPC-over-RDMA transports:
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
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
items for this operation to be returned inline) or large enough to
receive rpa_count bytes in a single element of the rpr_contents
array.
o If the Write chunk provided for a READ_PLUS operation by an NFS
version 4.2 client is not empty, an NFS version 4.2 server MUST
use that chunk for the first element of the rpr_contents array
that has an rpc_data arm.
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
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
in the reply, the NFS version 4.2 client SHOULD send additional
READ_PLUS requests for any remaining bytes.
4.3. NFS Version 4 COMPOUND Requests
A single NFS version 4 COMPOUND procedure supplies arguments for a
sequence of operations, and returns results from that sequence, all
in a single round-trip [RFC7530]. An NFS version 4 client MAY
construct an NFS version 4 COMPOUND procedure that provides more than
one chunk in the Read list or Write list as long as it observes the
restrictions in Section 4.1.
An NFS version 4 client provides XDR Position values in each Read
chunk to disambiguate which chunk is associated with which argument
data item. However NFS version 4 server and client implementations
must agree in advance on how to pair Write chunks with returned
result data items.
The mechanism specified in Section 5.3.2 of
[I-D.ietf-nfsv4-rfc5666bis]) is applied here, with some additional
restrictions. 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., either a READ, READ_PLUS, or READLINK operation).
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.
o The first chunk in the Write list MUST be used by the first NFS
Read operation in an NFS version 4 COMPOUND procedure. The next
Write chunk is used by the next NFS Read operation, and so on.
o If an NFS version 4 client has provided a matching non-empty Write
chunk, then the corresponding NFS Read operation MUST return its
DDP-eligible data item using that chunk.
o If an NFS version 4 client has provided an empty matching Write
chunk, then the corresponding NFS Read operation MUST return all
of its result data items inline.
o If an NFS Read operation returns a union arm which does not
contain a DDP-eligible result, and the NFS version 4 client has
provided a matching non-empty Write chunk, an NFS version 4 server
MUST return an empty Write chunk in that Write list position.
o If there are more NFS Read operations than Write chunks, then
remaining NFS Read operations in an NFS version 4 COMPOUND that
have no matching Write chunk MUST return their results inline.
4.3.1. 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 server consumes the provided Write chunks by writing B, and C. The NFS version 4 server consumes the provided Write
the results of the designated operations in the compound request, chunks by writing the results of the designated operations in the
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
NFS version 4 COMPOUND request: NFS version 4 COMPOUND request:
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 client does not want to have the READLINK result returned If the NFS version 4 client does not want to have the READLINK result
directly, it provides a zero-length array of segment triplets for returned via RDMA, it provides an empty Write chunk for buffer B to
buffer B or sets the values in the segment triplet for buffer B to indicate that the READLINK result must be returned inline.
zeros to indicate that the READLINK result must be returned inline.
Unlike NFS versions 2 and 3, the maximum size of an NFS version 4
COMPOUND is not bounded. However, typical NFS version 4 clients
rarely issue such problematic requests. In practice, NFS version 4
clients behave in much more predictable ways. Rsize and wsize apply
to COMPOUND operations by capping the total amount of data payload
allowed in each COMPOUND. An extension to NFS version 4 supporting a
comprehensive exchange of upper-layer message size parameters is part
of [RFC5661].
4.4. NFS Version 4 Callback 4.4. NFS Version 4 Callback
The NFS version 4 protocols support server-initiated callbacks to The NFS version 4 protocols support server-initiated callbacks to
notify clients of events such as recalled delegations. There are no notify clients of events such as recalled delegations.
DDP-eligible data items in callback protocols associated with
NFSv4.0, NFSv4.1, or NFSv4.2.
In NFS version 4.1 and 4.2, callback operations may appear on the 4.4.1. NFS Version 4.0 Callback
same connection as one used for NFS version 4 client requests. NFS
version 4 clients and servers MUST use the mechanism described in
[I-D.ietf-nfsv4-rpcrdma-bidirection] when backchannel operations are
conveyed on RPC-over-RDMA transports.
5. IANA Considerations NFS version 4.0 implementations typically employ a separate TCP
connection to handle callback operations, even when the forward
channel uses a RPC-over-RDMA transport. Therefore no Upper Layer
Binding for the NFS version 4.0 callback program is provided in this
document.
4.4.2. NFS Version 4.1 Callback
In NFS version 4.1 and later minor versions, callback operations may
appear on the same connection as is used for NFS version 4 forward
channel client requests. NFS version 4 clients and servers MUST use
the mechanism described in [I-D.ietf-nfsv4-rpcrdma-bidirection] when
backchannel operations are conveyed on RPC-over-RDMA transports.
The csa_back_chan_attrs argument of the CREATE_SESSION operation
contains a ca_maxresponsesize field. The value in this field can be
taken as the absolute maximum size of backchannel replies generated
by a replying NFS version 4 client.
There are no DDP-eligible data items in callback protocols associated
with NFS version 4.1 or NFS version 4.2. However, some callback
requests, such as messages that convey device ID information, may be
large, in which case a Long Call or Reply may be appropriate. When
the NFS version 4 client reports a backchannel ca_maxresponsesize
that is larger than the connection's inline thresholds, the NFS
version 4 client can support Long messages (i.e., Read chunks and
Reply chunks). Otherwise an NFS version 4 server MUST use Short
messages to convey backchannel operations.
See Section 4.1 for a discussion of how an NFS version 4 server
handles situations where an NFS version 4 client has provided
inadequate RDMA resources to convey a backchannel reply.
4.5. Connection Keep-Alive
NFS version 4 client implementations often rely on a transport-layer
keep-alive mechanism to detect when an NFS version 4 server has
become unresponsive. When an NFS server is no longer responsive,
client-side keep-alive terminates the connection, which in turn
triggers reconnection and RPC retransmission.
RDMA transports have no keep-alive mechanism. Without a disconnect
or new RPC traffic, RDMA transport connections can remain alive long
after an NFS server has become unresponsive. Once an NFS client has
consumed all available RPC-over-RDMA credits on that transport
connection, it will forever await a reply before sending another RPC
request.
NFS version 4 clients SHOULD reserve one RPC-over-RDMA credit to use
for periodic server or connection health assessment. This credit can
be used to drive an RPC request on an otherwise idle connection,
triggering either a quick affirmative server response or immediate
connection termination.
To prevent lease expiry, NFS version 4 clients should use a lease-
extending operation such as RENEW or SEQUENCE, rather than a NULL
request, when performing a periodic health assessment.
5. Extending NFS Upper Layer Bindings
RPC programs such as NFS are required to have an Upper Layer Binding
specification to interoperate on RPC-over-RDMA transports
[I-D.ietf-nfsv4-rfc5666bis]. Via standards action, the Upper Layer
Binding specified in this document can be extended to cover versions
of the NFS version 4 protocol specified after NFS version 4 minor
version 2. This includes NFS version 4 extensions that are
documented separately from a new minor version.
6. IANA Considerations
NFS use of direct data placement introduces a need for an additional NFS use of direct data placement introduces a need for an additional
NFS port number assignment for networks that share traditional UDP NFS port number assignment for networks that share traditional UDP
and TCP port spaces with RDMA services. The iWARP [RFC5041] and TCP port spaces with RDMA services. The iWARP [RFC5041]
[RFC5040] protocol is such an example (InfiniBand is not). [RFC5040] protocol is such an example (InfiniBand is not).
NFS servers for versions 2 and 3 [RFC1094] [RFC1813] traditionally NFS servers for versions 2 and 3 [RFC1094] [RFC1813] traditionally
listen for clients on UDP and TCP port 2049, and additionally, they listen for clients on UDP and TCP port 2049, and additionally, they
register these with the portmapper and/or rpcbind [RFC1833] service. register these with the portmapper and/or rpcbind [RFC1833] service.
However, [RFC7530] requires NFS servers for version 4 to listen on However, [RFC7530] requires NFS version 4 servers to listen on TCP
TCP port 2049, and they are not required to register. port 2049, and they are not required to register.
An NFS version 2 or version 3 server supporting RPC-over-RDMA on such 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 a network and registering itself with the RPC portmapper MAY choose
an arbitrary port, or MAY use the alternative well-known port number an arbitrary port, or MAY use the alternative well-known port number
for its RPC-over-RDMA service. The chosen port MAY be registered for its RPC-over-RDMA service. The chosen port MAY be registered
with the RPC portmapper under the netid assigned by the requirement with the RPC portmapper under the netid assigned by the requirement
in [I-D.ietf-nfsv4-rfc5666bis]. in [I-D.ietf-nfsv4-rfc5666bis].
An NFS version 4 server supporting RPC-over-RDMA on such a network 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 MUST use the alternative well-known port number for its RPC-over-RDMA
service. Clients SHOULD connect to this well-known port without service. Clients SHOULD connect to this well-known port without
consulting the RPC portmapper (as for NFSv4/TCP). 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 The port number assigned to an NFS service over an RPC-over-RDMA
transport is available from the IANA port registry [RFC3232]. transport is available from the IANA port registry [RFC3232].
6. Security Considerations 7. Security Considerations
The RDMA transport for RPC [I-D.ietf-nfsv4-rfc5666bis] supports all RPC-over-RDMA supports all RPC security models, including RPCSEC_GSS
RPC [RFC5531] security models, including RPCSEC_GSS [RFC2203] security and transport-level security [RFC2203]. The choice of RDMA
security and transport-level security. The choice of RDMA Read and Read and RDMA Write to convey RPC argument and results does not
RDMA Write to convey RPC argument and results does not affect this, affect this, since it changes only the method of data transfer.
since it only changes the method of data transfer. Specifically, the Specifically, the requirements of [I-D.ietf-nfsv4-rfc5666bis] ensure
requirements of [I-D.ietf-nfsv4-rfc5666bis] ensure that this choice that this choice does not introduce new vulnerabilities.
does not 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.
7. Acknowledgments
The author gratefully acknowledges the work of Brent Callaghan and
Tom Talpey on the original NFS Direct Data Placement specification
[RFC5667]. The author also wishes to thank Bill Baker and Greg
Marsden for their support of this work.
Dave Noveck provided excellent review, constructive suggestions, and
consistent navigational guidance throughout the process of drafting
this document.
Special thanks go to nfsv4 Working Group Chair Spencer Shepler and
nfsv4 Working Group Secretary Thomas Haynes for their support.
8. References 8. References
8.1. Normative References 8.1. Normative References
[I-D.ietf-nfsv4-minorversion2] [I-D.ietf-nfsv4-minorversion2]
Haynes, T., "NFS Version 4 Minor Version 2", draft-ietf- Haynes, T., "NFS Version 4 Minor Version 2", draft-ietf-
nfsv4-minorversion2-41 (work in progress), January 2016. nfsv4-minorversion2-41 (work in progress), January 2016.
[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
skipping to change at page 11, line 18 skipping to change at page 14, line 41
[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>.
[RFC5531] Thurlow, R., "RPC: Remote Procedure Call Protocol
Specification Version 2", RFC 5531, DOI 10.17487/RFC5531,
May 2009, <http://www.rfc-editor.org/info/rfc5531>.
[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>.
[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>.
8.2. Informative References 8.2. Informative References
[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>.
[RFC3232] Reynolds, J., Ed., "Assigned Numbers: RFC 1700 is Replaced [RFC3232] Reynolds, J., Ed., "Assigned Numbers: RFC 1700 is Replaced
skipping to change at page 12, line 14 skipping to change at page 15, line 37
[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>.
[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
Corrections and updates made necessary by new language in
[I-D.ietf-nfsv4-rfc5666bis] have been introduced. For example,
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,
have been removed. The term "mapping" has been replaced with the
term "binding" or "Upper Layer Binding" throughout the document.
Some material that duplicates what is in [I-D.ietf-nfsv4-rfc5666bis]
has been deleted.
Material required by [I-D.ietf-nfsv4-rfc5666bis] for Upper Layer
Bindings that was not present in [RFC5667] has been added, including
discussion of how each NFS version properly estimates the maximum
size of RPC replies.
Technical corrections have been made. For example, the mention of
12KB and 36KB inline thresholds have been removed. The reference to
a non-existant NFS version 4 SYMLINK operation has been replaced with
NFS version 4 CREATE(NF4LNK).
The discussion of NFS version 4 COMPOUND handling has been completed.
Some changes were made to the algorithm for matching DDP-eligible
results to Write chunks.
The following additional improvements have been made, relative to
[RFC5667]:
o An explicit discussion of NFS version 4.0 and NFS version 4.1
backchannel operation has replaced the previous treatment of
callback operations.
o A binding for NFS version 4.2 has been added that includes
discussion of new data-bearing operations like READ_PLUS.
o A section suggesting a mechanism for periodically assessing
connection health has been introduced.
o Language inconsistent with or contradictory to
[I-D.ietf-nfsv4-rfc5666bis] has been removed from Sections 2 and
3, and both Sections have been combined into Section 2 in the
present document.
o Ambiguous or erroneous uses of RFC2119 terms have been corrected.
o References to obsolete RFCs have been updated.
o An IANA Considerations Section has replaced the "Port Usage
Considerations" Section.
o Code excerpts have been removed, and figures have been modernized.
Appendix B. Acknowledgments
The author gratefully acknowledges the work of Brent Callaghan and
Tom Talpey on the original NFS Direct Data Placement specification
[RFC5667]. The author also wishes to thank Bill Baker and Greg
Marsden for their support of this work.
Dave Noveck provided excellent review, constructive suggestions, and
consistent navigational guidance throughout the process of drafting
this document. Dave also contributed the text of Section 4.1.1.
Thanks to Karen Deitke for her sharp observations about idempotency,
and the clarity of the discussion of NFS COMPOUNDs.
Special thanks go to Transport Area Director Spencer Dawkins, nfsv4
Working Group Chair Spencer Shepler, and nfsv4 Working Group
Secretary Thomas Haynes for their support.
Author's Address Author's Address
Charles Lever (editor) Charles Lever (editor)
Oracle Corporation Oracle Corporation
1015 Granger Avenue 1015 Granger Avenue
Ann Arbor, MI 48104 Ann Arbor, MI 48104
USA USA
Phone: +1 734 274 2396 Phone: +1 734 274 2396
Email: chuck.lever@oracle.com Email: chuck.lever@oracle.com
 End of changes. 53 change blocks. 
264 lines changed or deleted 496 lines changed or added

This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/