Internet Engineering Task Force (IETF) J. Lentini
Request for Comments: 7532 NetApp
Category: Standards Track R. Tewari
ISSN: 2070-1721 IBM Almaden
C. Lever, Ed.
Oracle Corporation
March 2015
Namespace Database (NSDB) Protocol for Federated File Systems
Abstract
This document describes a file system federation protocol that
enables file access and namespace traversal across collections of
independently administered fileservers. The protocol specifies a set
of interfaces by which fileservers with different administrators can
form a fileserver federation that provides a namespace composed of
the file systems physically hosted on and exported by the constituent
fileservers.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7532.
Lentini, et al. Standards Track [Page 1]RFC 7532 NSDB Protocol for Federated File Systems March 2015
Copyright Notice
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RFC 7532 NSDB Protocol for Federated File Systems March 2015
Table of Contents
1. Introduction ....................................................4
1.1. Requirements Language ......................................5
2. Overview of Features and Concepts ...............................5
2.1. File-Access Protocol .......................................5
2.2. File-Access Client .........................................5
2.3. Fileserver .................................................5
2.4. Referral ...................................................5
2.5. Namespace ..................................................6
2.6. Fileset ....................................................6
2.7. Fileset Name (FSN) .........................................6
2.8. Fileset Location (FSL) .....................................7
2.8.1. The NFS URI Scheme ..................................8
2.8.2. Mutual Consistency across Fileset Locations ........10
2.8.3. Caching of Fileset Locations .......................11
2.8.4. Generating a Referral from Fileset Locations .......12
2.9. Namespace Database (NSDB) .................................13
2.9.1. NSDB Client ........................................14
2.10. Junctions and Referrals ..................................14
2.11. Unified Namespace and the Root Fileset ...................15
2.12. UUID Considerations ......................................15
3. Examples .......................................................16
3.1. Creating a Fileset and Its FSL(s) .........................16
3.1.1. Creating a Fileset and an FSN ......................17
3.1.2. Adding a Replica of a Fileset ......................17
3.2. Junction Resolution .......................................17
3.3. Example Use Cases for Fileset Annotations .................18
4. NSDB Configuration and Schema ..................................19
4.1. LDAP Configuration ........................................19
4.2. LDAP Schema ...............................................21
4.2.1. LDAP Attributes ....................................23
4.2.2. LDAP Object Classes ................................38
5. NSDB Operations ................................................42
5.1. NSDB Operations for Administrators ........................43
5.1.1. Create an FSN ......................................43
5.1.2. Delete an FSN ......................................44
5.1.3. Create an FSL ......................................44
5.1.4. Delete an FSL ......................................47
5.1.5. Update an FSL ......................................48
5.2. NSDB Operations for Fileservers ...........................49
5.2.1. NSDB Container Entry (NCE) Enumeration .............49
5.2.2. Lookup FSLs for an FSN .............................49
5.3. NSDB Operations and LDAP Referrals ........................50
6. Security Considerations ........................................51
7. IANA Considerations ............................................52
7.1. Registry for the fedfsAnnotation Key Namespace ............52
7.2. Registry for FedFS Object Identifiers .....................52
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7.3. LDAP Descriptor Registration ..............................55
8. Glossary .......................................................58
9. References .....................................................60
9.1. Normative References ......................................60
9.2. Informative References ....................................62
Acknowledgments ...................................................64
Authors' Addresses ................................................65
1. Introduction
A federated file system enables file access and namespace traversal
in a uniform, secure, and consistent manner across multiple
independent fileservers within an enterprise or across multiple
enterprises.
This document specifies a set of protocols that allow fileservers,
possibly from different vendors and with different administrators, to
cooperatively form a federation containing one or more federated file
systems. Each federated file system's namespace is composed of the
file systems physically hosted on and exported by the federation's
fileservers. A federation comprises a common namespace across all
its fileservers. A federation can project multiple namespaces and
enable clients to traverse each one. A federation can contain an
arbitrary number of namespace repositories, each belonging to a
different administrative entity and each rendering a part of the
namespace. A federation might also have an arbitrary number of
administrative entities responsible for administering disjoint
subsets of the fileservers.
Traditionally, building a namespace that spans multiple fileservers
has been difficult for two reasons. First, the fileservers that
export pieces of the namespace are often not in the same
administrative domain. Second, there is no standard mechanism for
the fileservers to cooperatively present the namespace. Fileservers
may provide proprietary management tools, and in some cases, an
administrator may be able to use the proprietary tools to build a
shared namespace out of the exported file systems. However, relying
on vendor-specific proprietary tools does not work in larger
enterprises or when collaborating across enterprises because the
fileservers are likely to be from multiple vendors or use different
software versions, each with their own namespace protocols, with no
common mechanism to manage the namespace or exchange namespace
information.
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The federated file system protocols in this document define how to
construct a namespace accessible by a Network File System (NFS)
version 4.0 [RFC7530], NFSv4.1 [RFC5661], or newer client and have
been designed to accommodate other file-access protocols in the
future.
The requirements for federated file systems are described in
[RFC5716]. A protocol for administering a fileserver's namespace is
described in [RFC7533]. The mechanism for discovering the root of a
federated namespace is described in [RFC6641].
In the rest of the document, the term "fileserver" denotes a
fileserver that is part of a federation.
1.1. 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. Overview of Features and Concepts
2.1. File-Access Protocol
A file-access protocol is a network protocol for accessing data. The
NFSv4.0 protocol [RFC7530] is an example of a file-access protocol.
2.2. File-Access Client
File-access clients are standard, off-the-shelf network-attached
storage (NAS) clients that communicate with fileservers using a
standard file-access protocol.
2.3. Fileserver
Fileservers are servers that store physical fileset data or refer
file-access clients to other fileservers. A fileserver provides
access to its shared file system data via a file-access protocol. A
fileserver may be implemented in a number of different ways,
including a single system, a cluster of systems, or some other
configuration.
2.4. Referral
A referral is a mechanism by which a fileserver redirects a file-
access client to a different fileserver or export. The exact
information contained in a referral varies from one file-access
protocol to another. The NFSv4.0 protocol, for example, defines the
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fs_locations attribute for returning referral information to NFSv4.0
clients. The NFSv4.1 protocol introduces the fs_locations_info
attribute that can return richer referral information to its clients.
NFSv4.1 fileservers may use either attribute during a referral. Both
attributes are defined in [RFC5661].
2.5. Namespace
The goal of a unified namespace is to make all managed data available
to any file-access client via the same path in a common file system
namespace. This should be achieved with minimal or zero
configuration on file-access clients. In particular, updates to the
common namespace should not require configuration changes to any
file-access client.
Filesets, which are the units of data management, are a set of files
and directories. From the perspective of file-access clients, the
common namespace is constructed by mounting filesets that are
physically located on different fileservers. The namespace, which is
defined in terms of fileset names and locations, is stored in a set
of namespace repositories, each managed by an administrative entity.
The namespace schema defines the model used for populating,
modifying, and querying the namespace repositories. It is not
required by the federation that the namespace be common across all
fileservers. It should be possible to have several independently
rooted namespaces.
2.6. Fileset
A fileset is loosely defined as a set of files and the directory tree
that contains them. The fileset abstraction is the basic unit of
data management. Depending on the configuration, a fileset may be
anything from an individual directory of an exported file system to
an entire exported file system on a fileserver.
2.7. Fileset Name (FSN)
A fileset is uniquely represented by its fileset name (FSN). An FSN
is considered unique across a federation. After an FSN is created,
it is associated with one or more fileset locations (FSLs) on one or
more fileservers.
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An FSN consists of:
NsdbName: the network location of the Namespace Database (NSDB)
node that contains authoritative information for this FSN.
FsnUuid: a UUID (universally unique identifier), conforming to
[RFC4122], that is used to uniquely identify an FSN.
FsnTTL: the time-to-live of the FSN's FSL information, in
seconds. Fileservers MUST NOT use cached FSL records after the
parent FSN's FsnTTL has expired. An FsnTTL value of zero
indicates that fileservers MUST NOT cache the results of
resolving this FSN.
The NsdbName is not physically stored as an attribute of the record.
The NsdbName is obvious to any client that accesses an NSDB and is
indeed authenticated in cases where Transport Layer Security (TLS) is
in effect.
The FsnUuid and NsdbName values never change during an FSN's
lifetime. However, an FSN's FSL information can change over time and
is typically cached on fileservers for performance. More detail on
FSL caching is provided in Section 2.8.3.
An FSN record may also contain:
Annotations: name/value pairs that can be interpreted by a
fileserver. The semantics of this field are not defined by
this document. These tuples are intended to be used by higher-
level protocols.
Descriptions: text descriptions. The semantics of this field are
not defined by this document.
2.8. Fileset Location (FSL)
An FSL describes one physical location where a complete copy of the
fileset's data resides. An FSL contains generic and type-specific
information that together describe how to access the fileset data at
this location. An FSL's attributes can be used by a fileserver to
decide which locations it will return to a file-access client.
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An FSL consists of:
FslUuid: a UUID, conforming to [RFC4122], that is used to
uniquely identify an FSL.
FsnUuid: the UUID of the FSL's FSN.
NsdbName: the network location of the NSDB node that contains
authoritative information for this FSL.
The NsdbName is not stored as an attribute of an FSL record for the
same reason it is not stored in FSN records.
An FSL record may also contain:
Annotations: name/value pairs that can be interpreted by a
fileserver. The semantics of this field are not defined by
this document. These tuples are intended to be used by higher-
level protocols.
Descriptions: text descriptions. The semantics of this field are
not defined by this document.
In addition to the attributes defined above, an FSL record contains
attributes that allow a fileserver to construct referrals. For each
file-access protocol, a corresponding FSL record subtype is defined.
This document defines an FSL subtype for NFS. An NFS FSL contains
information suitable for use in one of the NFSv4 referral attributes
(e.g., fs_locations or fs_locations_info, described in [RFC5661]).
Section 4.2.2.4 describes the contents of an NFS FSL record.
A fileset may also be accessible by file-access protocols other than
NFS. The contents and format of such FSL subtypes are not defined in
this document.
2.8.1. The NFS URI Scheme
To capture the location of an NFSv4 fileset, we extend the NFS URL
scheme specified in [RFC2224]. This extension follows rules for
defining Uniform Resource Identifier schemes (see [RFC3986]). In the
following text, we refer to this extended NFS URL scheme as an NFS
URI.
An NFS URI MUST contain both an authority and a path component. It
MUST NOT contain a query component or a fragment component. Use of
the familiar "nfs" scheme name is retained.
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2.8.1.1. The NFS URI Authority Component
The rules for encoding the authority component of a generic URI are
specified in section 3.2 of [RFC3986]. The authority component of an
NFS URI MUST contain the host subcomponent. For globally scoped NFS
URIs, a hostname used in such URIs SHOULD be a fully qualified domain
name. See section 3.2.2 of [RFC3986] for rules on encoding non-ASCII
characters in hostnames.
An NFS URI MAY contain a port subcomponent as described in section
3.2.3 of [RFC3986]. If this subcomponent is missing, a port value of
2049 is assumed, as specified in [RFC7530], Section 3.1.
2.8.1.2. The NFS URI Path Component
The rules for encoding the path component of a generic URI are
specified in Section 3.3 of [RFC3986].
According to Sections 5 and 6 of [RFC2224], NFS URLs specify a
pathname relative to an NFS fileserver's public filehandle. However,
NFSv4 fileservers do not expose a public filehandle. Instead, NFSv4
pathnames contained in an NFS URI are evaluated relative to the
pseudoroot of the fileserver identified in the URI's authority
component.
Each component of an NFSv4 pathname is represented as a component4
string (see Section 3.2, "Basic Data Types", of [RFC5661]). The
component4 elements of an NFSv4 pathname are encoded as path segments
in an NFS URI. NFSv4 pathnames MUST be expressed in an NFS URI as an
absolute path. An NFS URI path component MUST NOT be empty. The NFS
URI path component starts with a slash ("/") character, followed by
one or more path segments that each start with a slash ("/")
character [RFC3986].
Therefore, a double slash always follows the authority component of
an NFS URI. For example, the NFSv4 pathname "/" is represented by
two slash ("/") characters following an NFS URI's authority
component.
The component names of an NFSv4 pathname MUST be prepared using the
component name rules defined in Section 12 ("Internationalization")
of [RFC7530] prior to encoding the path component of an NFS URI. As
specified in [RFC3986], any non-ASCII characters and any URI-reserved
characters, such as the slash ("/") character, contained in a
component4 element MUST be represented by URI percent encoding.
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2.8.1.3. Encoding an NFS Location in an FSL
The path component of an NFS URI encodes the rootpath field of the
NFSv4 fs_location4 data type or the "fli_rootpath" of the NFSv4
fs_locations_item4 data type (see [RFC5661]).
In its server field, the NFSv4 fs_location4 data type contains a list
of universal addresses and DNS labels. Each may optionally include a
port number. The exact encoding requirements for this information is
found in Section 12.6 of [RFC7530]. The NFSv4 fs_locations_item4
data type encodes the same data in its fli_entries field (see
[RFC5661]). This information is encoded in the authority component
of an NFS URI.
The server and fli_entries fields can encode multiple server
hostnames that share the same pathname. An NFS URI, and hence an FSL
record, represents only a single hostname and pathname pair. An NFS
fileserver MUST NOT combine a set of FSL records into a single
fs_location4 or fs_locations_item4 unless each FSL record in the set
contains the same rootpath value and extended file system
information.
2.8.2. Mutual Consistency across Fileset Locations
All of the FSLs that have the same FSN (and thereby reference the
same fileset) are equivalent from the point of view of access by a
file-access client. Different fileset locations for an FSN represent
the same data, though potentially at different points in time.
Fileset locations are equivalent but not identical. Locations may be
either read-only or read-write. Typically, multiple read-write
locations are backed by a clustered file system while read-only
locations are replicas created by a federation-initiated or external
replication operation. Read-only locations may represent consistent
point-in-time copies of a read-write location. The federation
protocols, however, cannot prevent subsequent changes to a read-only
location nor guarantee point-in-time consistency of a read-only
location if the read-write location is changing.
Regardless of the type, one file-access client may be referred to a
location described by one FSL while another client chooses to use a
location described by another FSL. Since updates to each fileset
location are not controlled by the federation protocol, it is the
responsibility of administrators to guarantee the functional
equivalence of the data.
The federation protocols do not guarantee that different fileset
locations are mutually consistent in terms of the currency of their
data. However, they provide a means to publish currency information
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so that all fileservers in a federation can convey the same
information to file-access clients during referrals. Clients use
this information to ensure they do not revert to an out-of-date
version of a fileset's data when switching between fileset locations.
NFSv4.1 provides guidance on how replication can be handled in such a
manner. In particular, see Section 11.7 of [RFC5661].
2.8.3. Caching of Fileset Locations
To resolve an FSN to a set of FSL records, a fileserver queries the
NSDB node named in the FSN for FSL records associated with this FSN.
The parent FSN's FsnTTL attribute (see Section 2.7) specifies the
period of time during which a fileserver may cache these FSL records.
The combination of FSL caching and FSL migration presents a
challenge. For example, suppose there are three fileservers named A,
B, and C. Suppose further that fileserver A contains a junction J to
fileset X stored on fileserver B (see Section 2.10 for a description
of junctions).
Now suppose that fileset X is migrated from fileserver B to
fileserver C, and the corresponding FSL information for fileset X in
the authoritative NSDB is updated.
If fileserver A has cached FSLs for fileset X, a file-access client
traversing junction J on fileserver A will be referred to fileserver
B, even though fileset X has migrated to fileserver C. If fileserver
A had not cached the FSL records, it would have queried the NSDB and
obtained the correct location of fileset X.
Typically, the process of fileset migration leaves a redirection on
the source fileserver in place of a migrated fileset (without such a
redirection, file-access clients would find an empty space where the
migrated fileset was, which defeats the purpose of a managed
migration).
This redirection might be a new junction that targets the same FSN as
other junctions referring to the migrated fileset, or it might be
some other kind of directive, depending on the fileserver
implementation, that simply refers file-access clients to the new
location of the migrated fileset.
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Back to our example. Suppose, as part of the migration process, a
junction replaces fileset X on fileserver B. Later, either:
o New file-access clients are referred to fileserver B by stale FSL
information cached on fileserver A, or
o File-access clients continue to access fileserver B because they
cache stale location data for fileset X.
In either case, thanks to the redirection, file-access clients are
informed by fileserver B that fileset X has moved to fileserver C.
Such redirecting junctions (here, on fileserver B) would not be
required to be in place forever. They need to stay in place at least
until FSL entries cached on fileservers and locations cached on file-
access clients for the target fileset are invalidated.
The FsnTTL field in the FSL's parent FSN (see Section 2.7) specifies
an upper bound for the lifetime of cached FSL information and thus
can act as a lower bound for the lifetime of redirecting junctions.
For example, suppose the FsnTTL field contains the value 3600 seconds
(one hour). In such a case, administrators SHOULD keep the
redirection in place for at least one hour after a fileset migration
has taken place because a referring fileserver might cache the FSL
data during that time before refreshing it.
To get file-access clients to access the destination fileserver more
quickly, administrators SHOULD set the FsnTTL field of the migrated
fileset to a low number or zero before migration begins. It can be
reset to a more reasonable number at a later point.
Note that some file-access protocols do not communicate location
cache expiry information to file-access clients. In some cases, it
may be difficult to determine an appropriate lifetime for redirecting
junctions because file-access clients may cache location information
indefinitely.
2.8.4. Generating a Referral from Fileset Locations
After resolving an FSN to a set of FSL records, the fileserver
generates a referral to redirect a file-access client to one or more
of the FSN's FSLs. The fileserver converts the FSL records to a
referral format understood by a particular file-access client, such
as an NFSv4 fs_locations or fs_locations_info attribute.
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To give file-access clients as many options as possible, the
fileserver SHOULD include the maximum possible number of FSL records
in a referral. However, the fileserver MAY omit some of the FSL
records from the referral. For example, the fileserver might omit an
FSL record because of limitations in the file-access protocol's
referral format.
For a given FSL record, the fileserver MAY convert or reduce the FSL
record's contents in a manner appropriate to the referral format.
For example, an NFS FSL record contains all the data necessary to
construct an fs_locations_info attribute, but an fs_locations_info
attribute contains several pieces of information that are not found
in the simpler fs_locations attribute. A fileserver constructs
entries in an fs_locations attribute using the relevant contents of
an NFS FSL record.
Whenever the fileserver converts or reduces FSL data, the fileserver
SHOULD attempt to maintain the original meaning where possible. For
example, an NFS FSL record contains the rank and order information
that is included in an fs_locations_info attribute (see NFSv4.1's
FSLI4BX_READRANK, FSLI4BX_READORDER, FSLI4BX_WRITERANK, and
FSLI4BX_WRITEORDER). While this rank and order information is not
explicitly expressible in an fs_locations attribute, the fileserver
can arrange the fs_locations attribute's locations list based on the
rank and order values.
Another example: A single NFS FSL record contains the hostname of one
fileserver. A single fs_locations attribute can contain a list of
fileserver names. An NFS fileserver MAY combine two or more FSL
records into a single entry in an fs_locations or fs_locations_info
array only if each FSL record contains the same pathname and extended
file system information.
Refer to Sections 11.9 and 11.10 of the NFSv4.1 protocol
specification [RFC5661] for further details.
2.9. Namespace Database (NSDB)
The NSDB service is a federation-wide service that provides
interfaces to define, update, and query FSN information, FSL
information, and FSN-to-FSL mapping information.
An individual repository of namespace information is called an NSDB
node. The difference between the NSDB service and an NSDB node is
analogous to that between the DNS service and a particular DNS
server.
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Each NSDB node is managed by a single administrative entity. A
single administrative entity can manage multiple NSDB nodes.
Each NSDB node stores the definition of the FSNs for which it is
authoritative. It also stores the definitions of the FSLs associated
with those FSNs. An NSDB node is authoritative for the filesets that
it defines.
An NSDB MAY be replicated throughout the federation. If an NSDB is
replicated, the NSDB MUST exhibit loose, converging consistency as
defined in [RFC3254]. The mechanism by which this is achieved is
outside the scope of this document. Many Lightweight Directory
Access Protocol (LDAP) implementations support replication. These
features MAY be used to replicate the NSDB.
2.9.1. NSDB Client
Each NSDB node supports an LDAP [RFC4510] interface. An NSDB client
is software that uses the LDAP protocol to access or update namespace
information stored on an NSDB node.
A domain's administrative entity uses NSDB client software to manage
information stored on NSDB nodes. Details of these transactions are
discussed in Section 5.1.
Fileservers act as an NSDB client when contacting a particular NSDB
node to resolve an FSN to a set of FSL records. The resulting
location information is then transferred to file-access clients via
referrals. Therefore, file-access clients never need to access NSDBs
directly. These transactions are described in Section 5.2.
2.10. Junctions and Referrals
A junction is a point in a particular fileset namespace where a
specific target fileset may be attached. If a file-access client
traverses the path leading from the root of a federated namespace to
the junction referring to a target fileset, it should be able to
mount and access the data in that target fileset (assuming
appropriate permissions). In other words, a junction can be viewed
as a reference from a directory in one fileset to the root of the
target fileset.
A junction can be implemented as a special marker on a directory or
by some other mechanism in the fileserver's underlying file system.
What data is used by the fileserver to represent junctions is not
defined by this document. The essential property is that given a
junction, a fileserver must be able to find the FSN for the target
fileset.
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When a file-access client reaches a junction, the fileserver refers
the client to a list of FSLs associated with the FSN targeted by the
junction. The client can then mount one of the associated FSLs.
The federation protocols do not limit where and how many times a
fileset is mounted in the namespace. Filesets can be nested; a
fileset can be mounted under another fileset.
2.11. Unified Namespace and the Root Fileset
The root fileset, when defined, is the top-level fileset of the
federation-wide namespace. The root of the unified namespace is the
top level directory of this fileset. A set of designated fileservers
in the federation can export the root fileset to render the
federation-wide unified namespace. When a file-access client mounts
the root fileset from any of these designated fileservers, it can
view a common federation-wide namespace.
2.12. UUID Considerations
To ensure FSN and FSL records are unique across a domain, Federated
File System (FedFS) employs UUIDs conforming to [RFC4122] to form the
distinguished names of LDAP records containing FedFS data (see
Section 4.2.2.2).
Because junctions store a tuple containing an FSN UUID and the name
and port of an NSDB node, an FSN UUID must be unique only on a single
NSDB node. An FSN UUID collision can be detected immediately when an
administrator attempts to publish an FSN or FSL by storing it under a
specific NSDB Container Entry (NCE) on an authoritative NSDB host.
Note that one NSDB node may store multiple NCEs, each under a
different namingContext. If an NSDB node must contain more than one
NCE, the federation's admin entity SHOULD provide a robust method for
preventing FSN UUID collisions between FSNs that reside on the same
NSDB node but under different NCEs.
Because FSLs are children of FSNs, FSL UUIDs must be unique for just
a single FSN. As with FSNs, as soon as an FSL is published, its
uniqueness is guaranteed.
A fileserver performs the operations described in Section 5.2 as an
unauthenticated user. Thus, distinguished names of FSN and FSL
records, as well as the FSN and FSL records themselves, are required
to be readable by anyone who can bind anonymously to an NSDB node.
Therefore, FSN and FSL UUIDs should be considered public information.
Lentini, et al. Standards Track [Page 15]
RFC 7532 NSDB Protocol for Federated File Systems March 2015
Version 1 UUIDs contain a host's Media Access Control (MAC) address
and a timestamp in the clear. This gives provenance to each UUID,
but attackers can use such details to guess information about the
host where the UUID was generated. Security-sensitive installations
should be aware that on externally facing NSDBs, UUIDs can reveal
information about the hosts where they are generated.
In addition, version 1 UUIDs depend on the notion that a hardware MAC
address is unique across machines. As virtual machines do not depend
on unique physical MAC addresses and, in any event, an administrator
can modify the physical MAC address, version 1 UUIDs are no longer
considered sufficient.
To minimize the probability of UUIDs colliding, a consistent
procedure for generating UUIDs should be used throughout a
federation. Within a federation, UUIDs SHOULD be generated using the
procedure described for version 4 of the UUID variant specified in
[RFC4122].
3. Examples
In this section we provide examples and discussion of the basic
operations facilitated by the federated file system protocol:
creating a fileset, adding a replica of a fileset, resolving a
junction, and creating a junction.
3.1. Creating a Fileset and Its FSL(s)
A fileset is the abstraction of a set of files and the directory tree
that contains them. The fileset abstraction is the fundamental unit
of data management in the federation. This abstraction is
implemented by an actual directory tree whose root location is
specified by a fileset location (FSL).
In this section, we describe the basic requirements for starting with
a directory tree and creating a fileset that can be used in the
federation protocols. Note that we do not assume that the process of
creating a fileset requires any transformation of the files or the
directory hierarchy. The only thing that is required by this process
is assigning the fileset a fileset name (FSN) and expressing the
location of the implementation of the fileset as an FSL.
There are many possible variations to this procedure, depending on
how the FSN that binds the FSL is created and whether other replicas
of the fileset exist, are known to the federation, and need to be
bound to the same FSN.
Lentini, et al. Standards Track [Page 16]
RFC 7532 NSDB Protocol for Federated File Systems March 2015
It is easiest to describe this in terms of how to create the initial
implementation of the fileset and then describe how to add replicas.
3.1.1. Creating a Fileset and an FSN
The following administrative steps create an FSN, which is used to
track all replicas of a single physical dataset.
1. Choose the NSDB node that will keep track of the FSL(s) and
related information for the fileset.
2. Create an FSN in the NSDB node.
The FSN UUID is chosen by the administrator or generated
automatically by administration software. The former case is
used if the fileset is being restored, perhaps as part of
disaster recovery, and the administrator wishes to specify the
FSN UUID in order to permit existing junctions that reference
that FSN to work again.
At this point, the FSN exists, but its fileset locations are
unspecified.
3. For the FSN created above, create an FSL in the NSDB node that
describes the physical location of the fileset data.
3.1.2. Adding a Replica of a Fileset
Adding a replica is straightforward: the NSDB node and the FSN are
already known. The only remaining step is to add another FSL.
Note that the federation protocols provide only the mechanisms to
register and unregister replicas of a fileset. Fileserver-to-
fileserver replication protocols are not defined.
3.2. Junction Resolution
A fileset may contain references to other filesets. These references
are represented by junctions. If a file-access client requests
access to a fileset object that is a junction, the fileserver
resolves the junction to discover one or more FSLs that implement the
referenced fileset.
There are many possible variations to this procedure, depending on
how the junctions are represented by the fileserver and how the
fileserver performs junction resolution.
Lentini, et al. Standards Track [Page 17]RFC 7532 NSDB Protocol for Federated File Systems March 2015
Step 4 is the only step that interacts directly with the federation
protocols. The rest of the steps may use platform-specific
interfaces.
1. The fileserver determines that the object being accessed is a
junction.
2. The fileserver does a local lookup to find the FSN of the target
fileset.
3. Using the FSN, the fileserver finds the NSDB node responsible for
the target FSN.
4. The fileserver contacts that NSDB node and asks for the set of
FSLs that implement the target FSN. The NSDB node responds with
a (possibly empty) set of FSLs.
5. The fileserver converts one or more of the FSLs to the location
type used by the file-access client (e.g., an NFSv4 fs_locations
attribute as described in [RFC5661]).
6. The fileserver redirects (in whatever manner is appropriate for
the client) the client to the location(s).
3.3. Example Use Cases for Fileset Annotations
Fileset annotations can convey additional attributes of a fileset.
For example, fileset annotations can be used to define relationships
between filesets that can be used by an auxiliary replication
protocol. Consider the scenario where a fileset is created and
mounted at some point in the namespace. A snapshot of the read-write
FSL of that fileset is taken periodically at different frequencies
(say, a daily or weekly snapshot). The different snapshots are
mounted at different locations in the namespace.
The daily snapshots are considered as different filesets from the
weekly ones, but both are related to the source fileset. We can
define an annotation labeling the filesets as source and replica.
The replication protocol can use this information to copy data from
one or more FSLs of the source fileset to all the FSLs of the replica
fileset. The replica filesets are read-only while the source fileset
is read-write.
This follows the traditional Andrew File System (AFS) model of
mounting the read-only volume at a path in the namespace different
from that of the read-write volume [AFS].
Lentini, et al. Standards Track [Page 18]RFC 7532 NSDB Protocol for Federated File Systems March 2015
The federation protocol does not control or manage the relationship
among filesets. It merely enables annotating the filesets with user-
defined relationships.
Another potential use for annotations is recording references to an
FSN. A single annotation containing the number of references could
be defined, or multiple annotations, one per reference, could be used
to store detailed information on the location of each reference.
As with the replication annotation described above, the maintenance
of reference information would not be controlled by the federation
protocol. The information would most likely be non-authoritative
because the ability to create a junction does not require the
authority to update the FSN record. In any event, such annotations
could be useful to administrators for determining if an FSN is
referenced by a junction.
4. NSDB Configuration and Schema
This section describes how an NSDB is constructed using an LDAP
Version 3 [RFC4510] directory. Section 4.1 describes the basic
properties of the LDAP configuration that MUST be used in order to
ensure compatibility between different implementations. Section 4.2
defines the new LDAP attribute types and the new object types; it
also specifies how the distinguished name (DN) of each object
instance MUST be constructed.
4.1. LDAP Configuration
An NSDB is constructed using an LDAP directory. This LDAP directory
MAY have multiple naming contexts. The LDAP directory's entry
specific to Digital Signature Algorithm (DSA) (its rootDSE) has a
multi-valued namingContext attribute. Each value of the
namingContext attribute is the DN of a naming context's root entry
(see [RFC4512]).
For each naming context that contains federation entries (e.g., FSNs
and FSLs):
1. There MUST be an LDAP entry that is superior to all of the naming
context's federation entries in the Directory Information Tree
(DIT). This entry is termed the NSDB Container Entry (NCE). The
NCE's children are FSNs. An FSN's children are FSLs.
2. The naming context's root entry MUST include
"fedfsNsdbContainerInfo" (defined in Section 4.2.2.1) as one of
its object classes. The fedfsNsdbContainerInfo's fedfsNceDN
attribute is used to locate the naming context's NCE.
Lentini, et al. Standards Track [Page 19]RFC 7532 NSDB Protocol for Federated File Systems March 2015
If a naming context does not contain federation entries, it will not
contain an NCE, and its root entry will not include a
"fedfsNsdbContainerInfo" as one of its object classes.
A fedfsNsdbContainerInfo's fedfsNceDN attribute contains the
distinguished name (DN) of the NSDB Container Entry residing under
this naming context. The fedfsNceDN attribute MUST NOT be empty.
For example, an LDAP directory might have the following entries:
-+ [root DSE]
| namingContext: o=fedfs
| namingContext: dc=example,dc=com
| namingContext: ou=system
|
|
+---- [o=fedfs]
| fedfsNceDN: o=fedfs
|
|
+---- [dc=example,dc=com]
| fedfsNceDN: ou=fedfs,ou=corp-it,dc=example,dc=com
|
|
+---- [ou=system]
In this case, the "o=fedfs" namingContext has an NSDB Container Entry
at "o=fedfs", the "dc=example,dc=com" namingContext has an NSDB
Container Entry at "ou=fedfs,ou=corp-it,dc=example,dc=com", and the
"ou=system" namingContext has no NSDB Container Entry.
The NSDB SHOULD be configured with one or more privileged LDAP users.
These users are able to modify the contents of the LDAP database. An
administrator that performs the operations described in Section 5.1
SHOULD authenticate using the DN of a privileged LDAP user.
It MUST be possible for an unprivileged (unauthenticated) user to
perform LDAP queries that access the NSDB data. A fileserver
performs the operations described in Section 5.2 as an unprivileged
user.
All implementations SHOULD use the same schema. At minimum, each
MUST use a schema that includes all objects named in the following
sections, with all associated attributes. If it is necessary for an
Lentini, et al. Standards Track [Page 20]RFC 7532 NSDB Protocol for Federated File Systems March 2015
implementation to extend the schema defined here, consider using one
of the following ways to extend the schema:
o Define a fedfsAnnotation key and values (see Section 4.2.1.6).
Register the new key and values with IANA (see Section 7.1).
o Define additional attribute types and object classes, then have
entries inherit from a class defined in this document and from the
implementation-defined ones.
Given the above configuration guidelines, an NSDB SHOULD be
constructed using a dedicated LDAP server. If LDAP directories are
needed for other purposes, such as to store user account information,
use of a separate LDAP server for those is RECOMMENDED. By using an
LDAP server dedicated to storing NSDB records, there is no need to
disturb the configuration of any other LDAP directories that store
information unrelated to an NSDB.
4.2. LDAP Schema
The schema definitions provided in this document use the LDAP schema
syntax defined in [RFC4512]. The definitions are formatted to allow
the reader to easily extract them from the document. The reader can
use the following shell script to extract the definitions:
<CODE BEGINS>
#!/bin/sh
grep '^ *///' | sed 's?^ */// ??' | sed 's?^ *///$??'
<CODE ENDS>
If the above script is stored in a file called "extract.sh", and this
document is in a file called "spec.txt", then the reader can do:
<CODE BEGINS>
sh extract.sh < spec.txt > fedfs.schema
<CODE ENDS>
The effect of the script is to remove leading white space from each
line, plus a sentinel sequence of "///".
Lentini, et al. Standards Track [Page 21]RFC 7532 NSDB Protocol for Federated File Systems March 2015
Code components extracted from this document must include the
following license:
<CODE BEGINS>
/// #
/// # Copyright (c) 2015 IETF Trust and the persons identified
/// # as authors of the code. All rights reserved.
/// #
/// # The authors of the code are:
/// # J. Lentini, C. Everhart, D. Ellard, R. Tewari, and M. Naik.
/// #
/// # Redistribution and use in source and binary forms, with
/// # or without modification, are permitted provided that the
/// # following conditions are met:
/// #
/// # - Redistributions of source code must retain the above
/// # copyright notice, this list of conditions and the
/// # following disclaimer.
/// #
/// # - Redistributions in binary form must reproduce the above
/// # copyright notice, this list of conditions and the
/// # following disclaimer in the documentation and/or other
/// # materials provided with the distribution.
/// #
/// # - Neither the name of Internet Society, IETF or IETF
/// # Trust, nor the names of specific contributors, may be
/// # used to endorse or promote products derived from this
/// # software without specific prior written permission.
/// #
/// # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS
/// # AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
/// # WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
/// # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
/// # FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
/// # EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
/// # LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
/// # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
/// # NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
/// # SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
/// # INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
/// # LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
/// # OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
/// # IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
/// # ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
/// #
<CODE ENDS>
Lentini, et al. Standards Track [Page 22]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.1. LDAP Attributes
The following definitions are used in this document:
o The name attribute described in [RFC4519].
o The Integer syntax (1.3.6.1.4.1.1466.115.121.1.27) described in
[RFC4517].
o The integerMatch rule described in [RFC4517].
o The Octet String syntax (1.3.6.1.4.1.1466.115.121.1.40) described
in [RFC4517].
o The octetStringMatch rule described in [RFC4517].
o The Boolean syntax (1.3.6.1.4.1.1466.115.121.1.7) described in
[RFC4517].
o The booleanMatch rule described in [RFC4517].
o The distinguishedNameMatch rule described in [RFC4517].
o The DN syntax (1.3.6.1.4.1.1466.115.121.1.12) described in
[RFC4517].
o The labeledURI attribute described in [RFC2079].
o The UUID syntax (1.3.6.1.1.16.1) described in [RFC4530].
o The UuidMatch rule described in [RFC4530].
o The UuidOrderingMatch rule described in [RFC4530].
Lentini, et al. Standards Track [Page 23]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.1.1. fedfsUuid
A fedfsUuid is the base type for all of the universally unique
identifiers (UUIDs) used by the federated file system protocols.
The fedfsUuid type is based on rules and syntax defined in [RFC4530].
A fedfsUuid is a single-valued LDAP attribute.
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.1 NAME 'fedfsUuid'
/// DESC 'A UUID used by NSDB'
/// EQUALITY uuidMatch
/// ORDERING uuidOrderingMatch
/// SYNTAX 1.3.6.1.1.16.1
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
4.2.1.2. fedfsFsnUuid
A fedfsFsnUuid represents the UUID component of an FSN. An NSDB
SHOULD ensure that no two FSNs it stores have the same fedfsFsnUuid.
This attribute is single-valued.
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.4 NAME 'fedfsFsnUuid'
/// DESC 'The FSN UUID component of an FSN'
/// SUP fedfsUuid
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
Lentini, et al. Standards Track [Page 24]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.1.3. fedfsFsnTTL
A fedfsFsnTTL is the time-to-live in seconds of a cached FSN and its
child FSL records. It corresponds to the FsnTTL as defined in
Section 2.7. See also Section 2.8.3 for information about caching
FSLs. A fedfsFsnTTL MUST be encoded as an Integer syntax value
[RFC4517] in the range [0, 4294967295].
This attribute is single-valued.
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.11 NAME 'fedfsFsnTTL'
/// DESC 'Time to live of an FSN tree'
/// EQUALITY integerMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.27 is the Integer syntax [RFC4517].
4.2.1.4. fedfsNceDN
A fedfsNceDN stores a distinguished name (DN).
This attribute is single-valued.
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.14 NAME 'fedfsNceDN'
/// DESC 'NCE Distinguished Name'
/// EQUALITY distinguishedNameMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.12
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.12 is the DN syntax [RFC4517].
Lentini, et al. Standards Track [Page 25]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.1.5. fedfsFslUuid
A fedfsFslUuid represents the UUID of an FSL. An NSDB SHOULD ensure
that no two FSLs it stores have the same fedfsFslUuid.
This attribute is single-valued.
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.8 NAME 'fedfsFslUuid'
/// DESC 'UUID of an FSL'
/// SUP fedfsUuid
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
4.2.1.6. fedfsAnnotation
A fedfsAnnotation contains an object annotation formatted as a key/
value pair.
This attribute is multi-valued; an object type that permits
annotations may have any number of annotations per instance.
A fedfsAnnotation attribute is a human-readable sequence of UTF-8
characters with no non-terminal NUL characters. The value MUST be
formatted according to the following ABNF [RFC5234] rules:
ANNOTATION = KEY "=" VALUE
KEY = ITEM
VALUE = ITEM
ITEM = *WSP DQUOTE UTF8-octets DQUOTE *WSP
DQUOTE and WSP are defined in [RFC5234], and UTF8-octets is defined
in [RFC3629].
The following escape sequences are allowed:
+-----------------+-------------+
| escape sequence | replacement |
+-----------------+-------------+
| \\ | \ |
| \" | " |
+-----------------+-------------+
Lentini, et al. Standards Track [Page 26]RFC 7532 NSDB Protocol for Federated File Systems March 2015
A fedfsAnnotation value might be processed as follows:
1. Parse the attribute value according to the ANNOTATION rule,
ignoring the escape sequences above.
2. Scan through results of the previous step and replace the escape
sequences above.
A fedfsAnnotation attribute that does not adhere to this format
SHOULD be ignored in its entirety. It MUST NOT prevent further
processing of its containing entry.
The following are examples of valid fedfsAnnotation attributes:
"key1" = "foo"
"another key" = "x=3"
"key-2" = "A string with \" and \\ characters."
"key3"="bar"
These correspond to the following key/value pairs:
+-------------+-----------------------------------+
| key | value |
+-------------+-----------------------------------+
| key1 | foo |
| another key | x=3 |
| key-2 | A string with " and \ characters. |
| key3 | bar |
+-------------+-----------------------------------+
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.12 NAME 'fedfsAnnotation'
/// DESC 'Annotation of an object'
/// SUP name
/// )
///
<CODE ENDS>
Lentini, et al. Standards Track [Page 27]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.1.7. fedfsDescr
A fedfsDescr stores an object description. The description MUST be
encoded as a UTF-8 string.
This attribute is multi-valued, which permits any number of
descriptions per entry.
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.13 NAME 'fedfsDescr'
/// DESC 'Description of an object'
/// SUP name
/// )
///
<CODE ENDS>
4.2.1.8. fedfsNfsURI
A fedfsNfsURI stores the host and pathname components of an FSL. A
fedfsNfsURI MUST be encoded as an NFS URI (see Section 2.8.1).
The fedfsNfsURI is a subtype of the labeledURI type [RFC2079], with
the same encoding rules.
This attribute is single-valued.
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.120 NAME 'fedfsNfsURI'
/// DESC 'Location of fileset'
/// SUP labeledURI
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
Lentini, et al. Standards Track [Page 28]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.1.9. fedfsNfsCurrency
A fedfsNfsCurrency stores the NFSv4.1 fs_locations_server's
fls_currency value [RFC5661]. A fedfsNfsCurrency MUST be encoded as
an Integer syntax value [RFC4517] in the range [-2147483648,
2147483647].
This attribute is single-valued.
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.103 NAME 'fedfsNfsCurrency'
/// DESC 'up-to-date measure of the data'
/// EQUALITY integerMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.27 is the Integer syntax [RFC4517].
4.2.1.10. fedfsNfsGenFlagWritable
A fedfsNfsGenFlagWritable stores the value of an FSL's NFSv4.1
FSLI4GF_WRITABLE bit [RFC5661]. A value of "TRUE" indicates the bit
is set. A value of "FALSE" indicates the bit is not set.
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.104 NAME 'fedfsNfsGenFlagWritable'
/// DESC 'Indicates if the file system is writable'
/// EQUALITY booleanMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.7
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.7 is the Boolean syntax [RFC4517].
Lentini, et al. Standards Track [Page 29]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.1.11. fedfsNfsGenFlagGoing
A fedfsNfsGenFlagGoing stores the value of an FSL's NFSv4.1
FSLI4GF_GOING bit [RFC5661]. A value of "TRUE" indicates the bit is
set. A value of "FALSE" indicates the bit is not set.
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.105 NAME 'fedfsNfsGenFlagGoing'
/// DESC 'Indicates if the file system is going'
/// EQUALITY booleanMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.7
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.7 is the Boolean syntax [RFC4517].
4.2.1.12. fedfsNfsGenFlagSplit
A fedfsNfsGenFlagSplit stores the value of an FSL's NFSv4.1
FSLI4GF_SPLIT bit [RFC5661]. A value of "TRUE" indicates the bit is
set. A value of "FALSE" indicates the bit is not set.
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.106 NAME 'fedfsNfsGenFlagSplit'
/// DESC 'Indicates if there are multiple file systems'
/// EQUALITY booleanMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.7
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.7 is the Boolean syntax [RFC4517].
Lentini, et al. Standards Track [Page 30]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.1.13. fedfsNfsTransFlagRdma
A fedfsNfsTransFlagRdma stores the value of an FSL's NFSv4.1
FSLI4TF_RDMA bit [RFC5661]. A value of "TRUE" indicates the bit is
set. A value of "FALSE" indicates the bit is not set.
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.107 NAME 'fedfsNfsTransFlagRdma'
/// DESC 'Indicates if the transport supports RDMA'
/// EQUALITY booleanMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.7
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.7 is the Boolean syntax [RFC4517].
4.2.1.14. fedfsNfsClassSimul
A fedfsNfsClassSimul contains the FSL's NFSv4.1 FSLI4BX_CLSIMUL
[RFC5661] value. A fedfsNfsClassSimul MUST be encoded as an Integer
syntax value [RFC4517] in the range [0, 255].
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.108 NAME 'fedfsNfsClassSimul'
/// DESC 'The simultaneous-use class of the file system'
/// EQUALITY integerMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.27 is the Integer syntax [RFC4517].
Lentini, et al. Standards Track [Page 31]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.1.15. fedfsNfsClassHandle
A fedfsNfsClassHandle contains the FSL's NFSv4.1 FSLI4BX_CLHANDLE
[RFC5661] value. A fedfsNfsClassHandle MUST be encoded as an Integer
syntax value [RFC4517] in the range [0, 255].
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.109 NAME 'fedfsNfsClassHandle'
/// DESC 'The handle class of the file system'
/// EQUALITY integerMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.27 is the Integer syntax [RFC4517].
4.2.1.16. fedfsNfsClassFileid
A fedfsNfsClassFileid contains the FSL's NFSv4.1 FSLI4BX_CLFILEID
[RFC5661] value. A fedfsNfsClassFileid MUST be encoded as an Integer
syntax value [RFC4517] in the range [0, 255].
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.110 NAME 'fedfsNfsClassFileid'
/// DESC 'The fileid class of the file system'
/// EQUALITY integerMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.27 is the Integer syntax [RFC4517].
Lentini, et al. Standards Track [Page 32]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.1.17. fedfsNfsClassWritever
A fedfsNfsClassWritever contains the FSL's NFSv4.1 FSLI4BX_CLWRITEVER
[RFC5661] value. A fedfsNfsClassWritever MUST be encoded as an
Integer syntax value [RFC4517] in the range [0, 255].
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.111 NAME 'fedfsNfsClassWritever'
/// DESC 'The write-verifier class of the file system'
/// EQUALITY integerMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.27 is the Integer syntax [RFC4517].
4.2.1.18. fedfsNfsClassChange
A fedfsNfsClassChange contains the FSL's NFSv4.1 FSLI4BX_CLCHANGE
[RFC5661] value. A fedfsNfsClassChange MUST be encoded as an Integer
syntax value [RFC4517] in the range [0, 255].
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.112 NAME 'fedfsNfsClassChange'
/// DESC 'The change class of the file system'
/// EQUALITY integerMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.27 is the Integer syntax [RFC4517].
Lentini, et al. Standards Track [Page 33]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.1.19. fedfsNfsClassReaddir
A fedfsNfsClassReaddir contains the FSL's NFSv4.1 FSLI4BX_CLREADDIR
[RFC5661] value. A fedfsNfsClassReaddir MUST be encoded as an
Integer syntax value [RFC4517] in the range [0, 255].
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.113 NAME 'fedfsNfsClassReaddir'
/// DESC 'The readdir class of the file system'
/// EQUALITY integerMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.27 is the Integer syntax [RFC4517].
4.2.1.20. fedfsNfsReadRank
A fedfsNfsReadRank contains the FSL's NFSv4.1 FSLI4BX_READRANK
[RFC5661] value. A fedfsNfsReadRank MUST be encoded as an Integer
syntax value [RFC4517] in the range [0, 255].
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.114 NAME 'fedfsNfsReadRank'
/// DESC 'The read rank of the file system'
/// EQUALITY integerMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.27 is the Integer syntax [RFC4517].
Lentini, et al. Standards Track [Page 34]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.1.21. fedfsNfsReadOrder
A fedfsNfsReadOrder contains the FSL's NFSv4.1 FSLI4BX_READORDER
[RFC5661] value. A fedfsNfsReadOrder MUST be encoded as an Integer
syntax value [RFC4517] in the range [0, 255].
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.115 NAME 'fedfsNfsReadOrder'
/// DESC 'The read order of the file system'
/// EQUALITY integerMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.27 is the Integer syntax [RFC4517].
4.2.1.22. fedfsNfsWriteRank
A fedfsNfsWriteRank contains the FSL's FSLI4BX_WRITERANK [RFC5661]
value. A fedfsNfsWriteRank MUST be encoded as an Integer syntax
value [RFC4517] in the range [0, 255].
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.116 NAME 'fedfsNfsWriteRank'
/// DESC 'The write rank of the file system'
/// EQUALITY integerMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.27 is the Integer syntax [RFC4517].
Lentini, et al. Standards Track [Page 35]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.1.23. fedfsNfsWriteOrder
A fedfsNfsWriteOrder contains the FSL's FSLI4BX_WRITEORDER [RFC5661]
value. A fedfsNfsWriteOrder MUST be encoded as an Integer syntax
value [RFC4517] in the range [0, 255].
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.117 NAME 'fedfsNfsWriteOrder'
/// DESC 'The write order of the file system'
/// EQUALITY integerMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.27 is the Integer syntax [RFC4517].
4.2.1.24. fedfsNfsVarSub
A fedfsNfsVarSub stores the value of an FSL's NFSv4.1 FSLI4IF_VAR_SUB
bit [RFC5661]. A value of "TRUE" indicates the bit is set. A value
of "FALSE" indicates the bit is not set.
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.118 NAME 'fedfsNfsVarSub'
/// DESC 'Indicates if variable substitution is present'
/// EQUALITY booleanMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.7
/// SINGLE-VALUE
/// )
///
<CODE ENDS>
OID 1.3.6.1.4.1.1466.115.121.1.7 is the Boolean syntax [RFC4517].
Lentini, et al. Standards Track [Page 36]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.1.25. fedfsNfsValidFor
A fedfsNfsValidFor stores an FSL's NFSv4.1 fs_locations_info
fli_valid_for value [RFC5661]. A fedfsNfsValidFor MUST be encoded as
an Integer syntax value [RFC4517] in the range [-2147483648,
2147483647].
An FSL's parent's fedfsFsnTTL value and its fedfsNfsValidFor value
MAY be different.
This attribute is single-valued.
<CODE BEGINS>
///
/// attributetype (
/// 1.3.6.1.4.1.31103.1.19 NAME 'fedfsNfsValidFor'
/// DESC 'Valid for time'
/// EQUALITY integerMatch
/// SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
/// SINGLE-VALUE
/// )
///
OID 1.3.6.1.4.1.1466.115.121.1.27 is the Integer syntax [RFC4517].
<CODE ENDS>
Lentini, et al. Standards Track [Page 37]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.2. LDAP Object Classes
4.2.2.1. fedfsNsdbContainerInfo
A fedfsNsdbContainerInfo describes the location of the NCE.
A fedfsNsdbContainerInfo's fedfsNceDN attribute is REQUIRED.
A fedfsNsdbContainerInfo's fedfsAnnotation and fedfsDescr attributes
are OPTIONAL.
<CODE BEGINS>
///
/// objectclass (
/// 1.3.6.1.4.1.31103.1.1001 NAME 'fedfsNsdbContainerInfo'
/// DESC 'Describes NCE location'
/// SUP top AUXILIARY
/// MUST (
/// fedfsNceDN
/// )
/// MAY (
/// fedfsAnnotation
/// $ fedfsDescr
/// ))
///
<CODE ENDS>
Lentini, et al. Standards Track [Page 38]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.2.2. fedfsFsn
A fedfsFsn represents an FSN.
A fedfsFsn's fedfsFsnUuid and fedfsFsnTTL attributes are REQUIRED.
A fedfsFsn's fedfsAnnotation and fedfsDescr attributes are OPTIONAL.
The DN of an FSN is REQUIRED to take the following form:
"fedfsFsnUuid=$FSNUUID,$NCE", where $FSNUUID is the UUID of the FSN
and $NCE is the DN of the NCE. Since LDAP requires a DN to be
unique, this ensures that each FSN entry has a unique UUID value
within the LDAP directory.
<CODE BEGINS>
///
/// objectclass (
/// 1.3.6.1.4.1.31103.1.1002 NAME 'fedfsFsn'
/// DESC 'Represents a fileset'
/// SUP top STRUCTURAL
/// MUST (
/// fedfsFsnUuid
/// $ fedfsFsnTTL
/// )
/// MAY (
/// fedfsAnnotation
/// $ fedfsDescr
/// ))
///
<CODE ENDS>
Lentini, et al. Standards Track [Page 39]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.2.3. fedfsFsl
The fedfsFsl object class represents an FSL.
The fedfsFsl is an abstract object class. Protocol-specific subtypes
of this object class are used to store FSL information. The
fedfsNfsFsl object class defined in Section 4.2.2.4 is used to record
an NFS FSL's location. Other subtypes MAY be defined for other
protocols (e.g., Common Internet File System (CIFS)).
A fedfsFsl's fedfsFslUuid and fedfsFsnUuid attributes are REQUIRED.
A fedfsFsl's fedfsAnnotation and fedfsDescr attributes are OPTIONAL.
The DN of an FSL is REQUIRED to take the following form:
"fedfsFslUuid=$FSLUUID,fedfsFsnUuid=$FSNUUID,$NCE", where $FSLUUID is
the FSL's UUID, $FSNUUID is the FSN's UUID, and $NCE is the DN of the
NCE. Since LDAP requires a DN to be unique, this ensures that each
FSL entry has a unique UUID value within the LDAP directory.
<CODE BEGINS>
///
/// objectclass (
/// 1.3.6.1.4.1.31103.1.1003 NAME 'fedfsFsl'
/// DESC 'A physical location of a fileset'
/// SUP top ABSTRACT
/// MUST (
/// fedfsFslUuid
/// $ fedfsFsnUuid
/// )
/// MAY (
/// fedfsAnnotation
/// $ fedfsDescr
/// ))
///
<CODE ENDS>
Lentini, et al. Standards Track [Page 40]RFC 7532 NSDB Protocol for Federated File Systems March 2015
4.2.2.4. fedfsNfsFsl
A fedfsNfsFsl is used to represent an NFS FSL. The fedfsNfsFsl
inherits all of the attributes of the fedfsFsl and extends the
fedfsFsl with information specific to the NFS protocol.
The DN of an NFS FSL is REQUIRED to take the following form:
"fedfsFslUuid=$FSLUUID,fedfsFsnUuid=$FSNUUID,$NCE", where $FSLUUID is
the FSL's UUID, $FSNUUID is the FSN's UUID, and $NCE is the DN of the
NCE. Since LDAP requires a DN to be unique, this ensures that each
NFS FSL entry has a unique UUID value within the LDAP directory.
<CODE BEGINS>
///
/// objectclass (
/// 1.3.6.1.4.1.31103.1.1004 NAME 'fedfsNfsFsl'
/// DESC 'An NFS location of a fileset'
/// SUP fedfsFsl STRUCTURAL
/// MUST (
/// fedfsNfsURI
/// $ fedfsNfsCurrency
/// $ fedfsNfsGenFlagWritable
/// $ fedfsNfsGenFlagGoing
/// $ fedfsNfsGenFlagSplit
/// $ fedfsNfsTransFlagRdma
/// $ fedfsNfsClassSimul
/// $ fedfsNfsClassHandle
/// $ fedfsNfsClassFileid
/// $ fedfsNfsClassWritever
/// $ fedfsNfsClassChange
/// $ fedfsNfsClassReaddir
/// $ fedfsNfsReadRank
/// $ fedfsNfsReadOrder
/// $ fedfsNfsWriteRank
/// $ fedfsNfsWriteOrder
/// $ fedfsNfsVarSub
/// $ fedfsNfsValidFor
/// ))
///
<CODE ENDS>
Lentini, et al. Standards Track [Page 41]RFC 7532 NSDB Protocol for Federated File Systems March 2015
5. NSDB Operations
The operations defined by the protocol can be described as several
sub-protocols that are used by entities within a federation to
perform different roles.
The first of these sub-protocols defines how the state of an NSDB
node can be initialized and updated. The primary use of this sub-
protocol is by an administrator to add, edit, or delete filesets,
their properties, and their fileset locations.
The second of these sub-protocols defines the queries that are sent
to an NSDB node in order to perform resolution (or to find other
information about the data stored within that NSDB node) and the
responses returned by the NSDB node. The primary use of this sub-
protocol is by a fileserver in order to perform resolution, but it
may also be used by an administrator to query the state of the
system.
The first and second sub-protocols are defined as LDAP operations,
using the schema defined in the previous section. If each NSDB node
is a standard LDAP server, then, in theory, it is unnecessary to
describe the LDAP operations in detail because the operations are
ordinary LDAP operations to query and update records. However, we do
not require that an NSDB node implement a complete LDAP service.
Therefore, we define the minimum level of LDAP functionality required
to implement an NSDB node.
The NSDB sub-protocols are defined in Section 5.1 and Section 5.2.
The descriptions of LDAP messages in these sections use the LDAP Data
Interchange Format (LDIF) [RFC2849]. In order to differentiate
constant and variable strings in the LDIF specifications, variables
are prefixed by a $ character and use all uppercase characters. For
example, a variable named FOO would be specified as $FOO.
This document uses the term "NSDB client" to refer to an LDAP client
that uses either of the NSDB sub-protocols.
The third sub-protocol defines the queries and other requests that
are sent to a fileserver in order to get information from it or to
modify the state of the fileserver in a manner related to the
federation protocols. The primary purpose of this protocol is for an
administrator to create or delete a junction or discover related
information about a particular fileserver.
The third sub-protocol is defined as an Open Network Computing (ONC)
Remote Procedure Call (RPC) protocol. The reason for using ONC RPC
Lentini, et al. Standards Track [Page 42]
RFC 7532 NSDB Protocol for Federated File Systems March 2015
instead of LDAP is that all fileservers support ONC RPC, but some do
not support an LDAP directory server.
The ONC RPC administration protocol is defined in [RFC7533].
5.1. NSDB Operations for Administrators
The admin entity initiates and controls the commands to manage
fileset and namespace information. The protocol used for
communicating between the admin entity and each NSDB node MUST be the
LDAPv3 [RFC4510] protocol.
The names we assign to these operations are entirely for the purpose
of exposition in this document and are not part of the LDAP dialogs.
5.1.1. Create an FSN
This operation creates a new FSN in the NSDB by adding a new fedfsFsn
entry in the NSDB's LDAP directory.
A fedfsFsn entry contains a fedfsFsnUuid. The administrator chooses
the fedfsFsnUuid by the process described in Section 2.12. A
fedfsFsn entry also contains a fedfsFsnTTL. The fedfsFsnTTL is
chosen by the administrator as described in Section 2.8.3.
5.1.1.1. LDAP Request
This operation is implemented using the LDAP ADD request described by
the LDIF below.
dn: fedfsFsnUuid=$FSNUUID,$NCE
changeType: add
objectClass: fedfsFsn
fedfsFsnUuid: $FSNUUID
fedfsFsnTTL: $TTL
For example, if $FSNUUID is "e8c4761c-eb3b-4307-86fc-f702da197966",
$TTL is "300" seconds, and $NCE is "o=fedfs", the operation would be:
dn: fedfsFsnUuid=e8c4761c-eb3b-4307-86fc-f702da197966,o=fedfs
changeType: add
objectClass: fedfsFsn
fedfsFsnUuid: e8c4761c-eb3b-4307-86fc-f702da197966
fedfsFsnTTL: 300
Lentini, et al. Standards Track [Page 43]RFC 7532 NSDB Protocol for Federated File Systems March 2015
5.1.2. Delete an FSN
This operation deletes an FSN by removing a fedfsFsn entry in the
NSDB's LDAP directory.
If the FSN entry being deleted has child FSL entries, this function
MUST return an error. This ensures that the NSDB will not contain
any orphaned FSL entries. A compliant LDAP implementation will meet
this requirement since Section 4.8 of [RFC4511] defines the LDAP
delete operation to only be capable of removing leaf entries.
Note that the FSN delete function removes the fileset only from a
federation namespace (by removing the records for that FSN from the
NSDB node that receives this request). The fileset and its data are
not deleted. Any junction that has this FSN as its target may
continue to point to this non-existent FSN. A dangling reference may
be detected when a fileserver tries to resolve a junction that refers
to the deleted FSN.
5.1.2.1. LDAP Request
This operation is implemented using the LDAP DELETE request described
by the LDIF below.
dn: fedfsFsnUuid=$FSNUUID,$NCE
changeType: delete
For example, if $FSNUUID is "e8c4761c-eb3b-4307-86fc-f702da197966"
and $NCE is "o=fedfs", the operation would be:
dn: fedfsFsnUuid=e8c4761c-eb3b-4307-86fc-f702da197966,o=fedfs
changeType: delete
5.1.3. Create an FSL
This operation creates a new FSL for the given FSN by adding a new
fedfsFsl entry in the NSDB's LDAP directory.
A fedfsFsl entry contains a fedfsFslUuid and fedfsFsnUuid. The
administrator chooses the fedfsFslUuid. The process for choosing the
fedfsFslUuid is described in Section 2.12. The fedfsFsnUuid is the
UUID of the FSL's FSN.
The administrator will also set additional attributes depending on
the FSL type.
Lentini, et al. Standards Track [Page 44]RFC 7532 NSDB Protocol for Federated File Systems March 2015
5.1.3.1. LDAP Request
This operation is implemented using the LDAP ADD request described by
the LDIF below (Note: the LDIF shows the creation of an NFS FSL.)
dn: fedfsFslUuid=$FSLUUID,fedfsFsnUuid=$FSNUUID,$NCE
changeType: add
objectClass: fedfsNfsFsl
fedfsFslUuid: $FSLUUID
fedfsFsnUuid: $FSNUUID
fedfsNfsURI: nfs://$HOST:$PORT//$PATH
fedfsNfsCurrency: $CURRENCY
fedfsNfsGenFlagWritable: $WRITABLE
fedfsNfsGenFlagGoing: $GOING
fedfsNfsGenFlagSplit: $SPLIT
fedfsNfsTransFlagRdma: $RDMA
fedfsNfsClassSimul: $CLASS_SIMUL
fedfsNfsClassHandle:$CLASS_HANDLE
fedfsNfsClassFileid:$CLASS_FILEID
fedfsNfsClassWritever:$CLASS_WRITEVER
fedfsNfsClassChange: $CLASS_CHANGE
fedfsNfsClassReaddir: $CLASS_READDIR
fedfsNfsReadRank: $READ_RANK
fedfsNfsReadOrder: $READ_ORDER
fedfsNfsWriteRank: $WRITE_RANK
fedfsNfsWriteOrder: $WRITE_ORDER
fedfsNfsVarSub: $VAR_SUB
fedfsNfsValidFor: $TIME
fedfsAnnotation: $ANNOTATION
fedfsDescr: $DESCR
For example, if $FSNUUID is "e8c4761c-eb3b-4307-86fc-f702da197966",
$FSLUUID is "ba89a802-41a9-44cf-8447-dda367590eb3", $HOST is
"server.example.com", $PORT is "20049", $PATH is stored in the file
"/tmp/fsl_path", $CURRENCY is "0" (an up-to-date copy), the FSL is
writable, but not going, split, or accessible via Remote Direct
Memory Access (RDMA), the simultaneous-use class is "1", the handle
class is "0", the fileid class is "1", the write-verifier class is
"1", the change class is "1", the readdir class is "9", the read rank
is "7", the read order is "8", the write rank is "5", the write order
is "6", variable substitution is false, $TIME is "300" seconds,
$ANNOTATION is ""foo" = "bar"", $DESC is "This is a description.",
and $NCE is "o=fedfs", the operation would be (for readability, the
DN is split into two lines):
Lentini, et al. Standards Track [Page 45]RFC 7532 NSDB Protocol for Federated File Systems March 2015
dn: fedfsFslUuid=ba89a802-41a9-44cf-8447-dda367590eb3,
fedfsFsnUuid=e8c4761c-eb3b-4307-86fc-f702da197966,o=fedfs
changeType: add
objectClass: fedfsNfsFsl
fedfsFslUuid: ba89a802-41a9-44cf-8447-dda367590eb3
fedfsFsnUuid: e8c4761c-eb3b-4307-86fc-f702da197966
fedfsNfsURI: nfs://server.example.com:20049//tmp/fsl_path
fedfsNfsCurrency: 0
fedfsNfsGenFlagWritable: TRUE
fedfsNfsGenFlagGoing: FALSE
fedfsNfsGenFlagSplit: FALSE
fedfsNfsTransFlagRdma: FALSE
fedfsNfsClassSimul: 1
fedfsNfsClassHandle: 0
fedfsNfsClassFileid: 1
fedfsNfsClassWritever: 1
fedfsNfsClassChange: 1
fedfsNfsClassReaddir: 9
fedfsNfsReadRank: 7
fedfsNfsReadOrder: 8
fedfsNfsWriteRank: 5
fedfsNfsWriteOrder: 6
fedfsNfsVarSub: FALSE
fedfsNfsValidFor: 300
fedfsAnnotation: "foo" = "bar"
fedfsDescr: This is a description.
5.1.3.2. Selecting fedfsNfsFsl Values
The fedfsNfsFSl object class is used to describe NFSv4-accessible
filesets. For the reasons described in Section 2.8.4, administrators
SHOULD choose reasonable values for all LDAP attributes of an
NFSv4-accessible fedfsNfsFsl even though some of these LDAP
attributes are not explicitly contained in an NFSv4 fs_locations
attribute.
When the administrator is unable to choose reasonable values for the
LDAP attributes not explicitly contained in an NFSv4 fs_locations
attribute, the values in the following table are RECOMMENDED.
Lentini, et al. Standards Track [Page 46]RFC 7532 NSDB Protocol for Federated File Systems March 2015
+-------------------------+----------+------------------------------+
| LDAP attribute | LDAP | Notes |
| | value | |
+-------------------------+----------+------------------------------+
| fedfsNfsCurrency | negative | Indicates that the server |
| | value | does not know the currency |
| | | (see Section 11.10.1 of |
| | | [RFC5661]). |
| fedfsNfsGenFlagWritable | FALSE | Leaving unset is not harmful |
| | | (see Section 11.10.1 of |
| | | [RFC5661]). |
| fedfsNfsGenFlagGoing | FALSE | NFS client will detect a |
| | | migration event if the FSL |
| | | becomes unavailable. |
| fedfsNfsGenFlagSplit | TRUE | Safe to assume that the FSL |
| | | is split. |
| fedfsNfsTransFlagRdma | TRUE | NFS client will detect if |
| | | RDMA access is available. |
| fedfsNfsClassSimul | 0 | 0 is treated as non-matching |
| | | (see Section 11.10.1 of |
| | | [RFC5661]). |
| fedfsNfsClassHandle | 0 | See fedfsNfsClassSimul note. |
| fedfsNfsClassFileid | 0 | See fedfsNfsClassSimul note. |
| fedfsNfsClassWritever | 0 | See fedfsNfsClassSimul note. |
| fedfsNfsClassChange | 0 | See fedfsNfsClassSimul note. |
| fedfsNfsClassReaddir | 0 | See fedfsNfsClassSimul note. |
| fedfsNfsReadRank | 0 | Highest value ensures FSL |
| | | will be tried. |
| fedfsNfsReadOrder | 0 | See fedfsNfsReadRank note. |
| fedfsNfsWriteRank | 0 | See fedfsNfsReadRank note. |
| fedfsNfsWriteOrder | 0 | See fedfsNfsReadRank note. |
| fedfsNfsVarSub | FALSE | NFSv4 does not define |
| | | variable substitution in |
| | | paths. |
| fedfsNfsValidFor | 0 | Indicates no appropriate |
| | | refetch interval (see |
| | | Section 11.10.2 of |
| | | [RFC5661]). |
+-------------------------+----------+------------------------------+
5.1.4. Delete an FSL
This operation deletes an FSL record. The admin requests the NSDB
node storing the fedfsFsl to delete it from its database. This
operation does not result in fileset data being deleted on any
fileserver.
Lentini, et al. Standards Track [Page 47]
RFC 7532 NSDB Protocol for Federated File Systems March 2015
5.1.4.1. LDAP Request
The admin sends an LDAP DELETE request to the NSDB node to remove the
FSL.
dn: fedfsFslUuid=$FSLUUID,fedfsFsnUuid=$FSNUUID,$NCE
changeType: delete
For example, if $FSNUUID is "e8c4761c-eb3b-4307-86fc-f702da197966",
$FSLUUID is "ba89a802-41a9-44cf-8447-dda367590eb3", and $NCE is
"o=fedfs", the operation would be (for readability, the DN is split
into two lines):
dn: fedfsFslUuid=ba89a802-41a9-44cf-8447-dda367590eb3,
fedfsFsnUuid=e8c4761c-eb3b-4307-86fc-f702da197966,o=fedfs
changeType: delete
5.1.5. Update an FSL
This operation updates the attributes of a given FSL. This command
results in a change in the attributes of the fedfsFsl at the NSDB
node maintaining this FSL. The values of the fedfsFslUuid and
fedfsFsnUuid attributes MUST NOT change during an FSL update.
5.1.5.1. LDAP Request
The admin sends an LDAP MODIFY request to the NSDB node to update the
FSL.
dn: fedfsFslUuid=$FSLUUID,fedfsFsnUuid=$FSNUUID,$NCE
changeType: modify
replace: $ATTRIBUTE-TYPE
For example, if $FSNUUID is "e8c4761c-eb3b-4307-86fc-f702da197966",
$FSLUUID is "ba89a802-41a9-44cf-8447-dda367590eb3", $NCE is
"o=fedfs", and the administrator wished to change the NFS read rank
to 10, the operation would be (for readability, the DN is split into
two lines):
dn: fedfsFslUuid=ba89a802-41a9-44cf-8447-dda367590eb3,
fedfsFsnUuid=e8c4761c-eb3b-4307-86fc-f702da197966,o=fedfs
changeType: modify
replace: fedfsNfsReadClass
fedfsNfsReadRank: 10
Lentini, et al. Standards Track [Page 48]RFC 7532 NSDB Protocol for Federated File Systems March 2015
5.2. NSDB Operations for Fileservers
5.2.1. NSDB Container Entry (NCE) Enumeration
To find the NCEs for the NSDB nsdb.example.com, a fileserver would do
the following:
nce_list = empty
connect to the LDAP directory at nsdb.example.com
for each namingContext value $BAR in the root DSE
/* $BAR is a DN */
query for a fedfsNceDN value at $BAR
/*
* The RFC 4516 LDAP URL for this search would be
*
* ldap://nsdb.example.com:389/$BAR?fedfsNceDN??
* (objectClass=fedfsNsdbContainerInfo)
*
*/
if a fedfsNceDN value is found
add the value to the nce_list
5.2.2. Lookup FSLs for an FSN
Using an LDAP search, the fileserver can obtain all of the FSLs for a
given FSN. The FSN's fedfsFsnUuid is used as the search key. The
following examples use the LDAP Uniform Resource Identifier (URI)
format defined in [RFC4516].
To obtain a list of all FSLs for $FSNUUID on the NSDB named
$NSDBNAME, the following search can be used (for readability, the URI
is split into two lines):
for each $NCE in nce_list
ldap://$NSDBNAME/fedfsFsnUuid=$FSNUUID,$NCE??one?
(objectClass=fedfsFsl)
This search is for the children of the object with DN
"fedfsFsnUuid=$FSNUUID,$NCE" with a filter for
"objectClass=fedfsFsl". The scope value of "one" restricts the
search to the entry's children (rather than the entire subtree below
the entry), and the filter ensures that only FSL entries are
returned.
For example, if $NSDBNAME is "nsdb.example.com", $FSNUUID is
"e8c4761c-eb3b-4307-86fc-f702da197966", and $NCE is "o=fedfs", the
search would be (for readability, the URI is split into three lines):
Lentini, et al. Standards Track [Page 49]RFC 7532 NSDB Protocol for Federated File Systems March 2015
ldap://nsdb.example.com/
fedfsFsnUuid=e8c4761c-eb3b-4307-86fc-f702da197966,o=fedfs
??one?(objectClass=fedfsFsl)
The following search can be used to obtain only the NFS FSLs for
$FSNUUID on the NSDB named $NSDBNAME (for readability, the URI is
split into two lines):
for each $NCE in nce_list
ldap://$NSDBNAME/fedfsFsnUuid=$FSNUUID,$NCE??one?
(objectClass=fedfsNfsFsl)
This also searches for the children of the object with DN
"fedfsFsnUuid=$FSNUUID,$NCE", but the filter for "objectClass =
fedfsNfsFsl" restricts the results to only NFS FSLs.
For example, if $NSDBNAME is nsdb.example.com, $FSNUUID is "e8c4761c-
eb3b-4307-86fc-f702da197966", and $NCE is "o=fedfs", the search would
be (for readability, the URI is split into three lines):
ldap://nsdb.example.com/
fedfsFsnUuid=e8c4761c-eb3b-4307-86fc-f702da197966,o=fedfs
??one?(objectClass=fedfsNfsFsl)
The fileserver will generate a referral based on the set of FSLs
returned by these queries using the process described in
Section 2.8.4.
5.3. NSDB Operations and LDAP Referrals
The LDAPv3 protocol defines an LDAP referral mechanism that allows an
LDAP server to redirect an LDAP client. LDAPv3 defines two types of
LDAP referrals: the Referral type defined in Section 4.1.10 of
[RFC4511] and the SearchResultReference type defined in Section 4.5.3
of [RFC4511]. In both cases, the LDAP referral lists one or more
URIs for services that can be used to complete the operation. In the
remainder of this document, the term "LDAP referral" is used to
indicate either of these types.
If an NSDB operation results in an LDAP referral, the NSDB client MAY
follow the LDAP referral. An NSDB client's decision to follow an
LDAP referral is implementation and configuration dependent. For
example, an NSDB client might be configured to follow only those LDAP
referrals that were received over a secure channel or only those that
target an NSDB that supports encrypted communication. If an NSDB
client chooses to follow an LDAP referral, the NSDB client MUST
process the LDAP referral and prevent looping as described in
Section 4.1.10 of [RFC4511].
Lentini, et al. Standards Track [Page 50]RFC 7532 NSDB Protocol for Federated File Systems March 2015
6. Security Considerations
Both the NFSv4 and LDAPv3 protocols provide security mechanisms.
When used in conjunction with the federated file system protocols
described in this document, the use of these mechanisms is
RECOMMENDED. Specifically, the use of RPCSEC_GSS [RFC2203], which is
built on the Generic Security Service Application Program Interface
(GSS-API) [RFC2743], is RECOMMENDED on all NFS connections between a
file-access client and fileserver. The security considerations
sections of the NFSv4.0 [RFC7530] and NFSv4.1 [RFC5661]
specifications contain special considerations for the handling of
GETATTR operations for the fs_locations and fs_locations_info
attributes.
NSDB nodes and NSDB clients MUST implement support for TLS [RFC5246],
as described in [RFC4513]. For all LDAP connections established by
the federated file system protocols, the use of TLS is RECOMMENDED.
If an NSDB client chooses to follow an LDAP referral, the NSDB client
SHOULD authenticate the LDAP referral's target NSDB using the target
NSDB's credentials (not the credentials of the NSDB that generated
the LDAP referral). The NSDB client SHOULD NOT follow an LDAP
referral that targets an NSDB for which it does not know the NSDB's
credentials.
Within a federation, there are two types of components an attacker
may compromise: a fileserver and an NSDB.
If an attacker compromises a fileserver, the attacker can interfere
with a file-access client's file system input/output (I/O) operations
(e.g., by returning fictitious data in the response to a read
request) or can fabricate a referral. The attacker's abilities are
the same regardless of whether or not the federation protocols are in
use. While the federation protocols do not give the attacker
additional capabilities, they are additional targets for attack. The
LDAP protocol described in Section 5.2 SHOULD be secured using the
methods described above to defeat attacks on a fileserver via this
channel.
If an attacker compromises an NSDB, the attacker will be able to
forge FSL information and thus poison the fileserver's referral
information. Therefore, an NSDB should be as secure as the
fileservers that query it. The LDAP operations described in
Section 5 SHOULD be secured using the methods described above to
defeat attacks on an NSDB via this channel.
Lentini, et al. Standards Track [Page 51]
RFC 7532 NSDB Protocol for Federated File Systems March 2015
A fileserver binds anonymously when performing NSDB operations.
Thus, the contents and distinguished names of FSN and FSL records are
required to be readable by anyone who can bind anonymously to an NSDB
service. Section 2.12 presents the security considerations in the
choice of the type of UUID used in these records.
It should be noted that the federation protocols do not directly
provide access to file system data. The federation protocols only
provide a mechanism for building a namespace. All data transfers
occur between a file-access client and fileserver just as they would
if the federation protocols were not in use. As a result, the
federation protocols do not require new user authentication and
authorization mechanisms or require a fileserver to act as a proxy
for a client.
7. IANA Considerations
7.1. Registry for the fedfsAnnotation Key Namespace
This document defines the fedfsAnnotation key in Section 4.2.1.6.
The fedfsAnnotation key namespace is managed by IANA. IANA has
created and now maintains a new registry entitled "FedFS Annotation
Keys". The location of this registry is under a new heading called
"Federated File System (FedFS) Parameters". The URL address is
<http://www.iana.org/assignments/fedfs-parameters>.
Future registrations are to be administered by IANA using the "First
Come First Served" policy defined in [RFC5226]. Registration
requests MUST include the key (a valid UTF-8 string of any length), a
brief description of the key's purpose, and an email contact for the
registration. For viewing, the registry should be sorted
lexicographically by key. There are no initial assignments for this
registry.
7.2. Registry for FedFS Object Identifiers
Using the process described in [RFC2578], one of the authors was
assigned the Internet Private Enterprise Numbers range
1.3.6.1.4.1.31103.x. Within this range, the subrange
1.3.6.1.4.1.31103.1.x is permanently dedicated for use by the
federated file system protocols. Unassigned OIDs in this range MAY
be used for Private Use or Experimental Use as defined in [RFC5226].
New permanent FedFS OID assignments MUST NOT be made using OIDs in
this range.
Lentini, et al. Standards Track [Page 52]
RFC 7532 NSDB Protocol for Federated File Systems March 2015
IANA has created and now maintains a new registry entitled "FedFS
Object Identifiers" for the purpose of recording the allocations of
FedFS Object Identifiers (OIDs) specified by this document. No
future allocations in this registry are allowed.
The location of this registry is under the heading "Federated File
System (FedFS) Parameters", created in Section 7.1. The URL address
is <http://www.iana.org/assignments/fedfs-parameters>.
For viewing, the registry has been sorted numerically by OID value.
The contents of the "FedFS Object Identifiers" registry are given in
Table 1.
Note: A descriptor designated below as "historic" reserves an OID
used in a past version of the NSDB protocol. Registering such OIDs
retains compatibility among existing implementations of the NSDB
protocol. This document does not otherwise refer to historic OIDs.
Lentini, et al. Standards Track [Page 53]
RFC 7532 NSDB Protocol for Federated File Systems March 2015
+---------------------------+--------------------------+-----------+
| OID | Description | Reference |
+---------------------------+--------------------------+-----------+
| 1.3.6.1.4.1.31103.1.1 | fedfsUuid | RFC 7532 |
| 1.3.6.1.4.1.31103.1.2 | fedfsNetAddr | historic |
| 1.3.6.1.4.1.31103.1.3 | fedfsNetPort | historic |
| 1.3.6.1.4.1.31103.1.4 | fedfsFsnUuid | RFC 7532 |
| 1.3.6.1.4.1.31103.1.5 | fedfsNsdbName | historic |
| 1.3.6.1.4.1.31103.1.6 | fedfsNsdbPort | historic |
| 1.3.6.1.4.1.31103.1.7 | fedfsNcePrefix | historic |
| 1.3.6.1.4.1.31103.1.8 | fedfsFslUuid | RFC 7532 |
| 1.3.6.1.4.1.31103.1.9 | fedfsFslHost | historic |
| 1.3.6.1.4.1.31103.1.10 | fedfsFslPort | historic |
| 1.3.6.1.4.1.31103.1.11 | fedfsFslTTL | historic |
| 1.3.6.1.4.1.31103.1.12 | fedfsAnnotation | RFC 7532 |
| 1.3.6.1.4.1.31103.1.13 | fedfsDescr | RFC 7532 |
| 1.3.6.1.4.1.31103.1.14 | fedfsNceDN | RFC 7532 |
| 1.3.6.1.4.1.31103.1.15 | fedfsFsnTTL | RFC 7532 |
| 1.3.6.1.4.1.31103.1.100 | fedfsNfsPath | historic |
| 1.3.6.1.4.1.31103.1.101 | fedfsNfsMajorVer | historic |
| 1.3.6.1.4.1.31103.1.102 | fedfsNfsMinorVer | historic |
| 1.3.6.1.4.1.31103.1.103 | fedfsNfsCurrency | RFC 7532 |
| 1.3.6.1.4.1.31103.1.104 | fedfsNfsGenFlagWritable | RFC 7532 |
| 1.3.6.1.4.1.31103.1.105 | fedfsNfsGenFlagGoing | RFC 7532 |
| 1.3.6.1.4.1.31103.1.106 | fedfsNfsGenFlagSplit | RFC 7532 |
| 1.3.6.1.4.1.31103.1.107 | fedfsNfsTransFlagRdma | RFC 7532 |
| 1.3.6.1.4.1.31103.1.108 | fedfsNfsClassSimul | RFC 7532 |
| 1.3.6.1.4.1.31103.1.109 | fedfsNfsClassHandle | RFC 7532 |
| 1.3.6.1.4.1.31103.1.110 | fedfsNfsClassFileid | RFC 7532 |
| 1.3.6.1.4.1.31103.1.111 | fedfsNfsClassWritever | RFC 7532 |
| 1.3.6.1.4.1.31103.1.112 | fedfsNfsClassChange | RFC 7532 |
| 1.3.6.1.4.1.31103.1.113 | fedfsNfsClassReaddir | RFC 7532 |
| 1.3.6.1.4.1.31103.1.114 | fedfsNfsReadRank | RFC 7532 |
| 1.3.6.1.4.1.31103.1.115 | fedfsNfsReadOrder | RFC 7532 |
| 1.3.6.1.4.1.31103.1.116 | fedfsNfsWriteRank | RFC 7532 |
| 1.3.6.1.4.1.31103.1.117 | fedfsNfsWriteOrder | RFC 7532 |
| 1.3.6.1.4.1.31103.1.118 | fedfsNfsVarSub | RFC 7532 |
| 1.3.6.1.4.1.31103.1.119 | fedfsNfsValidFor | RFC 7532 |
| 1.3.6.1.4.1.31103.1.120 | fedfsNfsURI | RFC 7532 |
| 1.3.6.1.4.1.31103.1.1001 | fedfsNsdbContainerInfo | RFC 7532 |
| 1.3.6.1.4.1.31103.1.1002 | fedfsFsn | RFC 7532 |
| 1.3.6.1.4.1.31103.1.1003 | fedfsFsl | RFC 7532 |
| 1.3.6.1.4.1.31103.1.1004 | fedfsNfsFsl | RFC 7532 |
+---------------------------+--------------------------+-----------+
Table 1
Lentini, et al. Standards Track [Page 54]RFC 7532 NSDB Protocol for Federated File Systems March 2015
7.3. LDAP Descriptor Registration
In accordance with Sections 3.4 and 4 of [RFC4520], the object
identifier descriptors defined in this document (listed below) have
been registered via the Expert Review process.
Subject: Request for LDAP Descriptor Registration
Person & email address to contact for further information: See
"Author/Change Controller"
Specification: RFC 7532
Author/Change Controller: IESG (iesg@ietf.org)
Object Identifier: 1.3.6.1.4.1.31103.1.1
Descriptor (short name): fedfsUuid
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.2
Descriptor (short name): fedfsNetAddr
Usage: attribute type (historic)
Object Identifier: 1.3.6.1.4.1.31103.1.3
Descriptor (short name): fedfsNetPort
Usage: attribute type (historic)
Object Identifier: 1.3.6.1.4.1.31103.1.4
Descriptor (short name): fedfsFsnUuid
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.5
Descriptor (short name): fedfsNsdbName
Usage: attribute type (historic)
Object Identifier: 1.3.6.1.4.1.31103.1.6
Descriptor (short name): fedfsNsdbPort
Usage: attribute type (historic)
Object Identifier: 1.3.6.1.4.1.31103.1.7
Descriptor (short name): fedfsNcePrefix
Usage: attribute type (historic)
Object Identifier: 1.3.6.1.4.1.31103.1.8
Descriptor (short name): fedfsFslUuid
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.9
Descriptor (short name): fedfsFslHost
Usage: attribute type (historic)
Lentini, et al. Standards Track [Page 55]RFC 7532 NSDB Protocol for Federated File Systems March 2015
Object Identifier: 1.3.6.1.4.1.31103.1.10
Descriptor (short name): fedfsFslPort
Usage: attribute type (historic)
Object Identifier: 1.3.6.1.4.1.31103.1.11
Descriptor (short name): fedfsFslTTL
Usage: attribute type (historic)
Object Identifier: 1.3.6.1.4.1.31103.1.12
Descriptor (short name): fedfsAnnotation
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.13
Descriptor (short name): fedfsDescr
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.14
Descriptor (short name): fedfsNceDN
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.15
Descriptor (short name): fedfsFsnTTL
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.100
Descriptor (short name): fedfsNfsPath
Usage: attribute type (historic)
Object Identifier: 1.3.6.1.4.1.31103.1.101
Descriptor (short name): fedfsNfsMajorVer
Usage: attribute type (historic)
Object Identifier: 1.3.6.1.4.1.31103.1.102
Descriptor (short name): fedfsNfsMinorVer
Usage: attribute type (historic)
Object Identifier: 1.3.6.1.4.1.31103.1.103
Descriptor (short name): fedfsNfsCurrency
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.104
Descriptor (short name): fedfsNfsGenFlagWritable
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.105
Descriptor (short name): fedfsNfsGenFlagGoing
Usage: attribute type
Lentini, et al. Standards Track [Page 56]
RFC 7532 NSDB Protocol for Federated File Systems March 2015
Object Identifier: 1.3.6.1.4.1.31103.1.106
Descriptor (short name): fedfsNfsGenFlagSplit
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.107
Descriptor (short name): fedfsNfsTransFlagRdma
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.108
Descriptor (short name): fedfsNfsClassSimul
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.109
Descriptor (short name): fedfsNfsClassHandle
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.110
Descriptor (short name): fedfsNfsClassFileid
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.111
Descriptor (short name): fedfsNfsClassWritever
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.112
Descriptor (short name): fedfsNfsClassChange
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.113
Descriptor (short name): fedfsNfsClassReaddir
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.114
Descriptor (short name): fedfsNfsReadRank
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.115
Descriptor (short name): fedfsNfsReadOrder
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.116
Descriptor (short name): fedfsNfsWriteRank
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.117
Descriptor (short name): fedfsNfsWriteOrder
Usage: attribute type
Lentini, et al. Standards Track [Page 57]
RFC 7532 NSDB Protocol for Federated File Systems March 2015
Object Identifier: 1.3.6.1.4.1.31103.1.118
Descriptor (short name): fedfsNfsVarSub
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.119
Descriptor (short name): fedfsNfsValidFor
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.120
Descriptor (short name): fedfsNfsURI
Usage: attribute type
Object Identifier: 1.3.6.1.4.1.31103.1.1001
Descriptor (short name): fedfsNsdbContainerInfo
Usage: object class
Object Identifier: 1.3.6.1.4.1.31103.1.1002
Descriptor (short name): fedfsFsn
Usage: object class
Object Identifier: 1.3.6.1.4.1.31103.1.1003
Descriptor (short name): fedfsFsl
Usage: object class
Object Identifier: 1.3.6.1.4.1.31103.1.1004
Descriptor (short name): fedfsNfsFsl
Usage: object class
8. Glossary
Administrator: A user with the necessary authority to initiate
administrative tasks on one or more servers.
Admin Entity: A server or agent that administers a collection of
fileservers and persistently stores the namespace information.
File-Access Client: Standard off-the-shelf, network-attached storage
(NAS) client software that communicates with fileservers using a
standard file-access protocol.
Federation: A set of fileserver collections and singleton
fileservers that use a common set of interfaces and protocols in
order to provide to file-access clients a federated namespace
accessible through a file system access protocol.
Fileserver: A server that stores physical fileset data or refers
file-access clients to other fileservers. A fileserver provides
access to its shared file system data via a file-access protocol.
Lentini, et al. Standards Track [Page 58]RFC 7532 NSDB Protocol for Federated File Systems March 2015
Fileset: The abstraction of a set of files and the directory tree
that contains them. A fileset is the fundamental unit of data
management in the federation.
Note that all files within a fileset are descendants of one
directory and that filesets do not span file systems.
File System: A self-contained unit of export for a fileserver and
the mechanism used to implement filesets. The fileset does not
need to be rooted at the root of the file system, nor at the
export point for the file system.
A single file system MAY implement more than one fileset, if the
file-access protocol and the fileserver permit this.
File-Access Protocol: A network file system access protocol such as
NFSv3 [RFC1813], NFSv4 [RFC7530], or CIFS (Common Internet File
System) [MS-SMB] [MS-SMB2] [MS-CIFS].
FSL (Fileset Location): The location of the implementation of a
fileset at a particular moment in time. An FSL MUST be something
that can be translated into a protocol-specific description of a
resource that a file-access client can access directly, such as an
fs_locations attribute (for NFSv4) or a share name (for CIFS).
FSN (Fileset Name): A platform-independent and globally unique name
for a fileset. Two FSLs that implement replicas of the same
fileset MUST have the same FSN, and if a fileset is migrated from
one location to another, the FSN of that fileset MUST remain the
same.
Junction: A file system object used to link a directory name in the
current fileset with an object within another fileset. The
server-side "link" from a leaf node in one fileset to the root of
another fileset.
Namespace: A filename/directory tree that a sufficiently authorized
file-access client can observe.
NSDB (Namespace Database) Service: A service that maps FSNs to FSLs.
The NSDB may also be used to store other information, such as
annotations for these mappings and their components.
NSDB Node: The name or location of a server that implements part of
the NSDB service and is responsible for keeping track of the FSLs
(and related information) that implement a given partition of the
FSNs.
Lentini, et al. Standards Track [Page 59]RFC 7532 NSDB Protocol for Federated File Systems March 2015
Referral: A server response to a file-access client access that
directs the client to evaluate the current object as a reference
to an object at a different location (specified by an FSL) in
another fileset and possibly hosted on another fileserver. The
client re-attempts the access to the object at the new location.
Replica: A redundant implementation of a fileset. Each replica
shares the same FSN but has a different FSL.
Replicas may be used to increase availability or performance.
Updates to replicas of the same fileset MUST appear to occur in
the same order; therefore, each replica is self-consistent at any
moment.
We do not assume that updates to each replica occur
simultaneously. If a replica is offline or unreachable, the other
replicas may be updated.
Server Collection: A set of fileservers administered as a unit. A
server collection may be administered with vendor-specific
software.
The namespace provided by a server collection could be part of the
federated namespace.
Singleton Server: A server collection containing only one server; a
stand-alone fileserver.
9. References
9.1. Normative References
[RFC2079] Smith, M., "Definition of an X.500 Attribute Type and an
Object Class to Hold Uniform Resource Identifiers (URIs)",
RFC 2079, January 1997,
<http://www.rfc-editor.org/info/rfc2079>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC2203] Eisler, M., Chiu, A., and L. Ling, "RPCSEC_GSS Protocol
Specification", RFC 2203, September 1997,
<http://www.rfc-editor.org/info/rfc2203>.
Lentini, et al. Standards Track [Page 60]RFC 7532 NSDB Protocol for Federated File Systems March 2015
[RFC2578] McCloghrie, K., Ed., Perkins, D., Ed., and J.
Schoenwaelder, Ed., "Structure of Management Information
Version 2 (SMIv2)", STD 58, RFC 2578, April 1999,
<http://www.rfc-editor.org/info/rfc2578>.
[RFC2743] Linn, J., "Generic Security Service Application Program
Interface Version 2, Update 1", RFC 2743, January 2000,
<http://www.rfc-editor.org/info/rfc2743>.
[RFC2849] Good, G., "The LDAP Data Interchange Format (LDIF) -
Technical Specification", RFC 2849, June 2000,
<http://www.rfc-editor.org/info/rfc2849>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003,
<http://www.rfc-editor.org/info/rfc3629>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, RFC
3986, January 2005,
<http://www.rfc-editor.org/info/rfc3986>.
[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122, July
2005, <http://www.rfc-editor.org/info/rfc4122>.
[RFC4510] Zeilenga, K., Ed., "Lightweight Directory Access Protocol
(LDAP): Technical Specification Road Map", RFC 4510, June
2006, <http://www.rfc-editor.org/info/rfc4510>.
[RFC4511] Sermersheim, J., Ed., "Lightweight Directory Access
Protocol (LDAP): The Protocol", RFC 4511, June 2006,
<http://www.rfc-editor.org/info/rfc4511>.
[RFC4512] Zeilenga, K., Ed., "Lightweight Directory Access Protocol
(LDAP): Directory Information Models", RFC 4512, June
2006, <http://www.rfc-editor.org/info/rfc4512>.
[RFC4513] Harrison, R., Ed., "Lightweight Directory Access Protocol
(LDAP): Authentication Methods and Security Mechanisms",
RFC 4513, June 2006,
<http://www.rfc-editor.org/info/rfc4513>.
[RFC4516] Smith, M., Ed. and T. Howes, "Lightweight Directory Access
Protocol (LDAP): Uniform Resource Locator", RFC 4516, June
2006, <http://www.rfc-editor.org/info/rfc4516>.
Lentini, et al. Standards Track [Page 61]RFC 7532 NSDB Protocol for Federated File Systems March 2015
[RFC4517] Legg, S., Ed., "Lightweight Directory Access Protocol
(LDAP): Syntaxes and Matching Rules", RFC 4517, June 2006,
<http://www.rfc-editor.org/info/rfc4517>.
[RFC4519] Sciberras, A., Ed., "Lightweight Directory Access Protocol
(LDAP): Schema for User Applications", RFC 4519, June
2006, <http://www.rfc-editor.org/info/rfc4519>.
[RFC4520] Zeilenga, K., "Internet Assigned Numbers Authority (IANA)
Considerations for the Lightweight Directory Access
Protocol (LDAP)", BCP 64, RFC 4520, June 2006,
<http://www.rfc-editor.org/info/rfc4520>.
[RFC4530] Zeilenga, K., "Lightweight Directory Access Protocol
(LDAP) entryUUID Operational Attribute", RFC 4530, June
2006, <http://www.rfc-editor.org/info/rfc4530>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008, <http://www.rfc-editor.org/info/rfc5226>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008,
<http://www.rfc-editor.org/info/rfc5234>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008,
<http://www.rfc-editor.org/info/rfc5246>.
[RFC5661] Shepler, S., Ed., Eisler, M., Ed., and D. Noveck, Ed.,
"Network File System (NFS) Version 4 Minor Version 1
Protocol", RFC 5661, 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, March 2015,
<http://www.rfc-editor.org/info/rfc7530>.
9.2. Informative References
[AFS] Howard, J., "An Overview of the Andrew File System",
Proceedings of the USENIX Winter Technical Conference ,
1988.
[MS-CIFS] Microsoft Corporation, "Common Internet File System (CIFS)
Protocol Specification", MS-CIFS 24.0, May 2014.
Lentini, et al. Standards Track [Page 62]RFC 7532 NSDB Protocol for Federated File Systems March 2015
[MS-SMB] Microsoft Corporation, "Server Message Block (SMB)
Protocol Specification", MS-SMB 43.0, May 2014.
[MS-SMB2] Microsoft Corporation, "Server Message Block (SMB) Version
2 Protocol Specification", MS-SMB2 46.0, May 2014.
[RFC1813] Callaghan, B., Pawlowski, B., and P. Staubach, "NFS
Version 3 Protocol Specification", RFC 1813, June 1995,
<http://www.rfc-editor.org/info/rfc1813>.
[RFC2224] Callaghan, B., "NFS URL Scheme", RFC 2224, October 1997,
<http://www.rfc-editor.org/info/rfc2224>.
[RFC3254] Alvestrand, H., "Definitions for talking about
directories", RFC 3254, April 2002,
<http://www.rfc-editor.org/info/rfc3254>.
[RFC5662] Shepler, S., Ed., Eisler, M., Ed., and D. Noveck, Ed.,
"Network File System (NFS) Version 4 Minor Version 1
External Data Representation Standard (XDR) Description",
RFC 5662, January 2010,
<http://www.rfc-editor.org/info/rfc5662>.
[RFC5716] Lentini, J., Everhart, C., Ellard, D., Tewari, R., and M.
Naik, "Requirements for Federated File Systems", RFC 5716,
January 2010, <http://www.rfc-editor.org/info/rfc5716>.
[RFC6641] Everhart, C., Adamson, W., and J. Zhang, "Using DNS SRV to
Specify a Global File Namespace with NFS Version 4", RFC
6641, June 2012, <http://www.rfc-editor.org/info/rfc6641>.
[RFC7533] Lentini, J., Tewari, R., and C. Lever, Ed.,
"Administration Protocol for Federated File Systems", RFC
7533, March 2015,
<http://www.rfc-editor.org/info/rfc7533>.
Lentini, et al. Standards Track [Page 63]RFC 7532 NSDB Protocol for Federated File Systems March 2015
Acknowledgments
Daniel Ellard contributed significant parts of this document.
The authors and editor would like to thank Craig Everhart and Manoj
Naik, who were co-authors of an earlier draft version of this
document. In addition, we would like to thank Andy Adamson, Paul
Lemahieu, Mario Wurzl, and Robert Thurlow for helping to author this
document.
We would like to thank George Amvrosiadis, Trond Myklebust, Howard
Chu, and Nicolas Williams for their comments and review.
The editor gratefully acknowledges the IESG reviewers, whose
constructive comments helped make this a much stronger document.
Finally, we would like to thank Andy Adamson, Rob Thurlow, and Tom
Haynes for helping to get this document out the door.
The extract.sh shell script and formatting conventions were first
described by the authors of the NFSv4.1 XDR specification [RFC5662].
Lentini, et al. Standards Track [Page 64]
RFC 7532 NSDB Protocol for Federated File Systems March 2015
Authors' Addresses
James Lentini
NetApp
1601 Trapelo Rd, Suite 16
Waltham, MA 02451
United States
Phone: +1 781-768-5359
EMail: jlentini@netapp.com
Renu Tewari
IBM Almaden
650 Harry Rd
San Jose, CA 95120
United States
EMail: tewarir@us.ibm.com
Charles Lever (editor)
Oracle Corporation
1015 Granger Avenue
Ann Arbor, MI 48104
United States
Phone: +1 248-614-5091
EMail: chuck.lever@oracle.com
Lentini, et al. Standards Track [Page 65]
