Network File System (NFS) Upper Layer Binding To RPC-Over-RDMA
draft-ietf-nfsv4-rfc5667bis-05
The information below is for an old version of the document.
| Document | Type | Active Internet-Draft (nfsv4 WG) | |
|---|---|---|---|
| Author | Chuck Lever | ||
| Last updated | 2017-02-03 | ||
| Stream | Internet Engineering Task Force (IETF) | ||
| Formats | plain text xml htmlized pdfized bibtex | ||
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| Stream | WG state | WG Document | |
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| Send notices to | (None) |
draft-ietf-nfsv4-rfc5667bis-05
Network File System Version 4 C. Lever, Ed.
Internet-Draft Oracle
Obsoletes: 5667 (if approved) February 3, 2017
Intended status: Standards Track
Expires: August 7, 2017
Network File System (NFS) Upper Layer Binding To RPC-Over-RDMA
draft-ietf-nfsv4-rfc5667bis-05
Abstract
This document specifies Upper Layer Bindings of Network File System
(NFS) protocol versions to RPC-over-RDMA. Upper Layer Bindings are
required to enable RPC-based protocols, such as NFS, to use Direct
Data Placement on RPC-over-RDMA. This document obsoletes 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
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 7, 2017.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
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publication of this document. Please review these documents
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Without obtaining an adequate license from the person(s) controlling
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than English.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conveying NFS Operations On RPC-Over-RDMA . . . . . . . . . . 3
3. Upper Layer Binding For NFS Versions 2 And 3 . . . . . . . . 4
4. Upper Layer Binding For NFS Version 4 . . . . . . . . . . . . 6
5. Extending NFS Upper Layer Bindings . . . . . . . . . . . . . 12
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
7. Security Considerations . . . . . . . . . . . . . . . . . . . 13
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
Appendix A. Changes Since RFC 5667 . . . . . . . . . . . . . . . 15
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . 17
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction
An RPC-over-RDMA transport, such as the one defined in
[I-D.ietf-nfsv4-rfc5666bis], may employ direct data placement to
convey data payloads associated with RPC transactions. To enable
successful interoperation, RPC client and server implementations must
agree as to which XDR data items in what particular RPC procedures
are eligible for direct data placement (DDP).
This document contains material required of Upper Layer Bindings, as
specified in [I-D.ietf-nfsv4-rfc5666bis], for the following NFS
protocol versions:
o NFS Version 2 [RFC1094]
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o NFS Version 3 [RFC1813]
o NFS Version 4.0 [RFC7530]
o NFS Version 4.1 [RFC5661]
o NFS Version 4.2 [RFC7862]
Upper Layer Bindings specified in this document apply to all versions
of RPC-over-RDMA.
2. Conveying NFS Operations On RPC-Over-RDMA
Definitions of terminology and a general discussion of how RPC-over-
RDMA is used to convey RPC transactions can be found in
[I-D.ietf-nfsv4-rfc5666bis]. In this section, these general
principles are applied in the context of conveying NFS procedures on
RPC-over-RDMA. Some issues common to all NFS protocol versions are
introduced.
2.1. DDP Eligibility Violations
To report a DDP-eligibity violation, an NFS server MUST return one
of:
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 ERR_CHUNK; or
o An RPC message (via an RDMA_MSG message) with the xid field set to
the XID of the matching NFS Call, the mtype field set to REPLY,
the stat field set to MSG_ACCEPTED, and the accept_stat field set
to GARBAGE_ARGS.
Subsequent sections of this document describe further considerations
particular to specific NFS protocols or procedures.
2.2. Reply Size Estimation
During the construction of each RPC Call message, an NFS client is
responsible for allocating appropriate resources for receiving the
matching Reply message. A Reply buffer overrun can result in
corruption of the Reply message or termination of the transport
connection. Therefore reliable reply size estimation is necessary to
ensure successful interoperation. This is particularly critical, for
example, when allocating a Reply chunk.
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In many cases the Upper Layer Protocol's XDR definition provides
enough information to enable the client to make a reliable prediction
of the maximum size of the expected Reply message. If there are
variable-size data items in the result, the maximum size of the RPC
Reply message can be reliably estimated in most cases:
o The client requests only a specific portion of an object (for
example, using the "count" and "offset" fields in an NFS READ).
o The client has already cached the size of the whole object it is
about to request (say, via a previous NFS GETATTR request).
o The client and server have negotiated a maximum size for all calls
and responses.
Subsequent sections of this document describe considerations
particular to specific NFS procedures where it is not possible to
determine the maximum Reply message size based solely on the above
criteria.
3. Upper Layer Binding For NFS Versions 2 And 3
This Upper Layer Binding specification applies to NFS Version 2
[RFC1094] and NFS Version 3 [RFC1813]. For brevity, in this section
a "legacy NFS client" refers to an NFS client using NFS version 2 or
NFS version 3 to communicate with an NFS server. Likewise, a "legacy
NFS server" is an NFS server communicating with clients using NFS
version 2 or NFS version 3.
The following XDR data items in NFS versions 2 and 3 are DDP-
eligible:
o The opaque file data argument in the NFS WRITE procedure
o The pathname argument in the NFS SYMLINK procedure
o The opaque file data result in the NFS READ procedure
o The pathname result in the NFS READLINK procedure
All other argument or result data items in NFS versions 2 and 3 are
not DDP-eligible.
A legacy server's response to a DDP-eligibility violation (described
in Section 2.1) 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.
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A legacy NFS client determines the maximum reply size for each
operation using the basic criteria outlined in Section 2.2.
3.1. Auxiliary Protocols
NFS versions 2 and 3 are typically deployed with several other
protocols, sometimes referred to as "NFS auxiliary protocols." These
are separate RPC programs that define procedures which are not part
of the NFS version 2 or version 3 RPC programs. These include:
o The MOUNT and NLM protocols, introduced in an appendix of
[RFC1813]
o The NSM protocol, described in Chapter 11 of [NSM]
o The NFSACL protocol, which does not have a public definition
(NFSACL here is treated as a de facto standard as there are
several interoperating implementations).
RPC-over-RDMA considers these programs as distinct Upper Layer
Protocols [I-D.ietf-nfsv4-rfc5666bis]. To enable the use of these
ULPs on an RPC-over-RDMA transport, an Upper Layer Binding
specification is provided here for each.
3.1.1. MOUNT, NLM, And NSM Protocols
Typically MOUNT, NLM, and NSM are conveyed via TCP, even in
deployments where NFS operations on RPC-over-RDMA. When a legacy
server supports these programs on RPC-over-RDMA, it advertises the
port address via the usual rpcbind service [RFC1833].
No operation in these protocols conveys a significant data payload,
and the size of RPC messages in these protocols is uniformly small.
Therefore, no XDR data items in these protocols are DDP-eligible.
The largest variable-length XDR data item is an xdr_netobj. In most
implementations this data item is not larger than 1024 bytes, making
reliable reply size estimation straightforward using the criteria
outlined in Section 2.2.
3.1.2. NFSACL Protocol
Legacy clients and servers that support the NFSACL RPC program
typically convey NFSACL procedures on the same connection as the NFS
RPC program. This obviates the need for separate rpcbind queries to
discover server support for this RPC program.
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ACLs are typically small, but even large ACLs must be encoded and
decoded to some degree. Thus no data item in this Upper Layer
Protocol is DDP-eligible.
For procedures whose replies do not include an ACL object, the size
of a reply is determined directly from the NFSACL program's XDR
definition.
There is no protocol-wide size limit for NFS version 3 ACLs, and
there is no mechanism in either the NFSACL or NFS programs for a
legacy client to ascertain the largest ACL a legacy server can store.
Legacy client implementations should choose a maximum size for ACLs
based on their own internal limits. A recommended lower bound for
this maximum is 32,768 bytes.
When an especially large ACL is expected, a Reply chunk might be
required. If a legacy NFS server indicates that it cannot return an
NFSACL GETACL response because the legacy NFS client has not provided
a large enough Reply chunk to receive that response, the legacy NFS
client can choose to
o Terminate the NFSACL GETACL with an error, or
o Allocate a larger Reply chunk and send the same NFSACL GETACL
request as a new RPC transaction. The NFS client should avoid
retrying the request indefinitely.
4. Upper Layer Binding For NFS Version 4
This Upper Layer Binding specification applies to all protocols
defined in NFS Version 4.0 [RFC7530], NFS Version 4.1 [RFC5661], and
NFS Version 4.2 [RFC7862].
4.1. DDP-Eligibility
Only the following XDR data items in the COMPOUND procedure of all
NFS version 4 minor versions are DDP-eligible:
o The opaque data field in the WRITE4args structure
o The linkdata field of the NF4LNK arm in the createtype4 union
o The opaque data field in the READ4resok structure
o The linkdata field in the READLINK4resok structure
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o In minor version 2 and newer, the rpc_data field of the
read_plus_content union (further restrictions on the use of this
data item follow below).
4.1.1. READ_PLUS Replies
The NFS version 4.2 READ_PLUS operation returns a complex data type
[RFC7862]. The rpr_contents field in the result of this operation is
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.
4.2. NFS Version 4 Reply Size Estimation
Within NFS version 4, there are certain variable-length result data
items whose maximum size cannot be estimated by clients reliably
because there is no protocol-specified size limit on these arrays.
These include:
o The attrlist4 field
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o Fields containing ACLs such as fattr4_acl, fattr4_dacl,
fattr4_sacl
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
layout metadata, such as loc_body, loh_body, da_addr_body,
lou_body, lrf_body, fattr_layout_types and fs_layout_types,
4.2.1. Reply Size Estimation For Minor Version 0
The NFSv4.0 protocol itself does not impose any bound on the size of
NFS calls or responses.
Some of the data items enumerated in Section 4.2 (in particular, the
items related to ACLs and fs_locations) make it difficult to predict
the maximum size of NFSv4.0 GETATTR replies that interrogate
variable-length attributes. As discussed in Section 2.2, client
implementations can rely on their own internal architectural limits
to bound the reply size, but such limits are not always guaranteed to
be reliable.
When an especially large NFSv4.0 GETATTR result is expected, a Reply
chunk might be required. If an NFSv4.0 server indicates that it
cannot return an NFSv4.0 GETATTR response because the requesting
NFSv4.0 client has not provided a large enough Reply chunk to receive
that response, the NFSv4.0 client can choose to
o Terminate the NFSv4.0 GETATTR with an error, or
o Allocate a larger Reply chunk and send the same NFSv4.0 GETATTR
request as a new RPC transaction. The NFS client should avoid
retrying the request indefinitely.
The use of NFS COMPOUND operations raises the possibility of requests
that combine a non-idempotent operation (eg. NFS WRITE) with an
NFSv4.0 GETATTR that requests one or more variable length results.
This combination should be avoided by ensuring that any NFSv4.0
GETATTR operation that might return a result of unpredictable length
is sent in an NFS COMPOUND by itself.
4.2.2. Reply Size Estimation For Minor Version 1 And Newer
In NFS version 4.1 and newer minor versions, the csa_fore_chan_attrs
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 replies generated by a replying NFS
version 4 server.
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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.
4.3. NFS Version 4 COMPOUND Requests
The NFS version 4 COMPOUND procedure allows the transmission of more
than one DDP-eligible data item per Call and Reply message. An NFS
version 4 client provides XDR Position values in each Read chunk to
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 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 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 READ
operation in an NFS version 4 COMPOUND procedure. The next Write
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
chunk, then the corresponding 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 READ operation MUST return all of
its result data items inline.
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
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 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.
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4.3.1. NFS Version 4 COMPOUND Example
The following example shows a Write list with three Write chunks, A,
B, and C. The NFS version 4 server consumes the provided Write
chunks by writing the results of the designated operations in the
compound request (READ and READLINK) back to each chunk.
Write list:
A --> B --> C
NFS version 4 COMPOUND request:
PUTFH LOOKUP READ PUTFH LOOKUP READLINK PUTFH LOOKUP READ
| | |
v v v
A B C
If the NFS version 4 client does not want to have the READLINK result
returned via RDMA, it provides an empty Write chunk for buffer B to
indicate that the READLINK result must be returned inline.
4.4. NFS Version 4 Callback
The NFS version 4 protocols support server-initiated callbacks to
notify clients of events such as recalled delegations.
4.4.1. NFS Version 4.0 Callback
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.
No operation in the NFS version 4.0 callback RPC program conveys a
significant data payload. Therefore, no XDR data items in this RPC
program is DDP-eligible.
A CB_RECALL reply is small and fixed in size. The CB_GETATTR reply
contains a variable-length fattr4 data item. See Section 4.2.1 for a
discussion of reply size prediction for this data item.
An NFS version 4.0 client advertises netids and ad hoc port addresses
for contacting its NFS version 4.0 callback service using the
SETCLIENTID operation.
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4.4.2. NFS Version 4.1 Callback
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
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 procedures defined
in NFS version 4.1 or NFS version 4.2. However, some callback
operations, such as messages that convey device ID information, can
be large, in which case a Long Call or Reply might be required.
When an NFS version 4.1 client can support Long Calls in its
backchannel, it reports a backchannel ca_maxrequestsize that is
larger than the connection's inline thresholds. Otherwise an NFS
version 4 server MUST use only Short messages to convey backchannel
operations.
4.5. Session-Related Considerations
Typically 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 (eg. SEQUENCE) 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.
When an NFS session operates on an RPC-over-RDMA transport, there are
a few additional cases where an RPC transaction can fail. 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. These situations are
no different from existing RPC errors which an NFS session
implementation is already prepared to handle for other transports.
As with other transports during such a failure, there might be no
SEQUENCE result available to the requester to distinguish whether
failure occurred before or after the requested operations were
executed on the responder. When a transport error occurs (eg.
RDMA_ERROR), the requester proceeds as usual to match the incoming
XID value to a waiting RPC Call. The RPC transaction is terminated,
and the result status is reported to the Upper Layer Protocol. The
requester's session implementation then determines the session ID and
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slot for the failed request, and performs slot recovery to make that
slot usable again. If this is not done, that slot could be rendered
permanently unavailable.
4.6. Retransmission And Keep-Alive
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.
Some RDMA transports (such as Reliable Connections on InfiniBand)
have no keep-alive mechanism. Without a disconnect or new RPC
traffic, such 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.
In addition to network partition and request loss scenarios, RPC-
over-RDMA connections can be terminated when a Transport header is
malformed, messages are larger than receive resources, or when too
many RPC-over-RDMA messages are sent at once. In such cases:
o If there is a transport error indicated (ie, RDMA_ERROR) before
the disconnect or instead of a disconnect, the requester MUST
respond to that error as prescribed by the specification of the
RPC transport. Then the NFS version 4 rules for handling
retransmission apply.
o If there is a transport disconnect and the responder has provided
no other response for a request, then only the NFS version 4 rules
for handling retransmission apply.
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
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version 2, or separately published extensions to an existing NFS
version 4 minor version, as described in [I-D.ietf-nfsv4-versioning].
6. IANA Considerations
NFS use of direct data placement introduces a need for an additional
NFS port number assignment for networks that share traditional UDP
and TCP port spaces with RDMA services. The iWARP [RFC5041]
[RFC5040] protocol is such an example (InfiniBand is not).
NFS servers for versions 2 and 3 [RFC1094] [RFC1813] traditionally
listen for clients on UDP and TCP port 2049, and additionally, they
register these with the portmapper and/or rpcbind [RFC1833] service.
However, [RFC7530] requires NFS version 4 servers to listen on TCP
port 2049, and they are not required to register.
An NFS version 2 or version 3 server supporting RPC-over-RDMA on such
a network and registering itself with the RPC portmapper MAY choose
an arbitrary port, or MAY use the alternative well-known port number
for its RPC-over-RDMA service. The chosen port MAY be registered
with the RPC portmapper under the netid assigned by the requirement
in [I-D.ietf-nfsv4-rfc5666bis].
An NFS version 4 server supporting RPC-over-RDMA on such a network
MUST use the alternative well-known port number for its RPC-over-RDMA
service. Clients SHOULD connect to this well-known port without
consulting the RPC portmapper (as for NFS version 4 on TCP
transports).
The port number assigned to an NFS service over an RPC-over-RDMA
transport is available from the IANA port registry [RFC3232].
7. Security Considerations
RPC-over-RDMA supports all RPC security models, including RPCSEC_GSS
security and transport-level security [RFC2203]. The choice of what
Direct Data Placement mechanism to convey RPC argument and results
does not affect this, since it changes only the method of data
transfer. Specifically, the requirements of
[I-D.ietf-nfsv4-rfc5666bis] ensure that this choice does not
introduce new vulnerabilities.
Because this document defines only the binding of the NFS protocols
atop [I-D.ietf-nfsv4-rfc5666bis], all relevant security
considerations are therefore to be described at that layer.
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8. References
8.1. Normative References
[I-D.ietf-nfsv4-rfc5666bis]
Lever, C., Simpson, W., and T. Talpey, "Remote Direct
Memory Access Transport for Remote Procedure Call, Version
One", draft-ietf-nfsv4-rfc5666bis-09 (work in progress),
January 2017.
[I-D.ietf-nfsv4-rpcrdma-bidirection]
Lever, C., "Bi-directional Remote Procedure Call On RPC-
over-RDMA Transports", draft-ietf-nfsv4-rpcrdma-
bidirection-06 (work in progress), January 2017.
[RFC1833] Srinivasan, R., "Binding Protocols for ONC RPC Version 2",
RFC 1833, DOI 10.17487/RFC1833, August 1995,
<http://www.rfc-editor.org/info/rfc1833>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC2203] Eisler, M., Chiu, A., and L. Ling, "RPCSEC_GSS Protocol
Specification", RFC 2203, DOI 10.17487/RFC2203, September
1997, <http://www.rfc-editor.org/info/rfc2203>.
[RFC5661] Shepler, S., Ed., Eisler, M., Ed., and D. Noveck, Ed.,
"Network File System (NFS) Version 4 Minor Version 1
Protocol", RFC 5661, DOI 10.17487/RFC5661, January 2010,
<http://www.rfc-editor.org/info/rfc5661>.
[RFC7530] Haynes, T., Ed. and D. Noveck, Ed., "Network File System
(NFS) Version 4 Protocol", RFC 7530, DOI 10.17487/RFC7530,
March 2015, <http://www.rfc-editor.org/info/rfc7530>.
[RFC7862] Haynes, T., "Network File System (NFS) Version 4 Minor
Version 2 Protocol", RFC 7862, DOI 10.17487/RFC7862,
November 2016, <http://www.rfc-editor.org/info/rfc7862>.
8.2. Informative References
[I-D.ietf-nfsv4-versioning]
Noveck, D., "Rules for NFSv4 Extensions and Minor
Versions", draft-ietf-nfsv4-versioning-09 (work in
progress), December 2016.
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[NSM] The Open Group, "Protocols for Interworking: XNFS, Version
3W", February 1998.
[RFC1094] Nowicki, B., "NFS: Network File System Protocol
specification", RFC 1094, DOI 10.17487/RFC1094, March
1989, <http://www.rfc-editor.org/info/rfc1094>.
[RFC1813] Callaghan, B., Pawlowski, B., and P. Staubach, "NFS
Version 3 Protocol Specification", RFC 1813,
DOI 10.17487/RFC1813, June 1995,
<http://www.rfc-editor.org/info/rfc1813>.
[RFC3232] Reynolds, J., Ed., "Assigned Numbers: RFC 1700 is Replaced
by an On-line Database", RFC 3232, DOI 10.17487/RFC3232,
January 2002, <http://www.rfc-editor.org/info/rfc3232>.
[RFC5040] Recio, R., Metzler, B., Culley, P., Hilland, J., and D.
Garcia, "A Remote Direct Memory Access Protocol
Specification", RFC 5040, DOI 10.17487/RFC5040, October
2007, <http://www.rfc-editor.org/info/rfc5040>.
[RFC5041] Shah, H., Pinkerton, J., Recio, R., and P. Culley, "Direct
Data Placement over Reliable Transports", RFC 5041,
DOI 10.17487/RFC5041, October 2007,
<http://www.rfc-editor.org/info/rfc5041>.
[RFC5667] Talpey, T. and B. Callaghan, "Network File System (NFS)
Direct Data Placement", RFC 5667, DOI 10.17487/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
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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.
Requirements to ignore extra Read or Write chunks have been removed
from the NFS version 2 and 3 Upper Layer Binding, as they conflict
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
has been added.
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.
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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 4.5
Thanks to Karen Deitke for her sharp observations about idempotency,
and the clarity of the discussion of NFS COMPOUNDs and NFS sessions.
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
Charles Lever (editor)
Oracle Corporation
1015 Granger Avenue
Ann Arbor, MI 48104
USA
Phone: +1 248 816 6463
Email: chuck.lever@oracle.com
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