NFSv4 Working Group J. Lentini Internet-Draft C. Everhart Intended status: Standards Track NetApp Expires: January 11, 2010 D. Ellard BBN Technologies R. Tewari M. Naik IBM Almaden July 10, 2009 NSDB Protocol for Federated Filesystems draft-ietf-nfsv4-federated-fs-protocol-02 Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on January 11, 2010. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Lentini, et al. Expires January 11, 2010 [Page 1] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 Abstract This document describes a filesystem 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 filesystems physically hosted on and exported by the constituent fileservers. 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]. Lentini, et al. Expires January 11, 2010 [Page 2] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Overview of Features and Concepts . . . . . . . . . . . . . . 4 2.1. Namespace . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2. Fileset and Fileset Name (FSN) . . . . . . . . . . . . . . 5 2.3. Fileset Location (FSL) . . . . . . . . . . . . . . . . . . 6 2.3.1. Mutual Consistency across Fileset Locations . . . . . 7 2.3.2. Caching of Fileset Locations . . . . . . . . . . . . . 8 2.4. Namespace Database (NSDB) . . . . . . . . . . . . . . . . 8 2.5. Mount Points, Junctions and Referrals . . . . . . . . . . 9 2.6. Unified Namespace and the Root Fileset . . . . . . . . . . 10 2.7. Fileservers . . . . . . . . . . . . . . . . . . . . . . . 10 2.8. File-access Clients . . . . . . . . . . . . . . . . . . . 10 3. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.1. Creating a Fileset and its FSL(s) . . . . . . . . . . . . 11 3.1.1. Creating a Fileset and an FSN . . . . . . . . . . . . 11 3.1.2. Adding a Replica of a Fileset . . . . . . . . . . . . 12 3.2. Junction Resolution . . . . . . . . . . . . . . . . . . . 12 3.3. Example Use Case for Fileset Annotations . . . . . . . . . 12 4. Mapping the NSDB onto LDAP . . . . . . . . . . . . . . . . . . 13 4.1. Basic LDAP Configuration . . . . . . . . . . . . . . . . . 13 4.2. LDAP Schema . . . . . . . . . . . . . . . . . . . . . . . 14 4.2.1. LDAP Attributes . . . . . . . . . . . . . . . . . . . 14 4.2.2. LDAP Objects . . . . . . . . . . . . . . . . . . . . . 21 5. NSDB Operations . . . . . . . . . . . . . . . . . . . . . . . 24 5.1. NSDB Operations for Administrators . . . . . . . . . . . . 24 5.1.1. Create an FSN . . . . . . . . . . . . . . . . . . . . 25 5.1.2. Delete an FSN . . . . . . . . . . . . . . . . . . . . 26 5.1.3. Create an FSL . . . . . . . . . . . . . . . . . . . . 26 5.1.4. Delete an FSL . . . . . . . . . . . . . . . . . . . . 27 5.1.5. Update an FSL . . . . . . . . . . . . . . . . . . . . 27 5.2. NSDB Operations for Fileservers . . . . . . . . . . . . . 28 5.2.1. Lookup FSLs for an FSN . . . . . . . . . . . . . . . . 28 6. Security Considerations . . . . . . . . . . . . . . . . . . . 29 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29 7.1. LDAP Descriptor Registration . . . . . . . . . . . . . . . 30 8. Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 33 9.1. Normative References . . . . . . . . . . . . . . . . . . . 33 9.2. Informational References . . . . . . . . . . . . . . . . . 34 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 35 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 35 Lentini, et al. Expires January 11, 2010 [Page 3] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 1. Introduction A federated filesystem 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 filesystems. Each federated filesystem's namespace is composed of the filesystems physically hosted on and exported by the federation's fileservers. A federation MAY contain a common namespace across all its fileservers. A federation MAY project multiple namespaces and enable clients to traverse each one. A federation MAY contain an arbitrary number of namespace repositories, each belonging to a different administrative entity, and each rendering a part of the namespace. A federation MAY 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 filesystems. However, relying on vendor-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. The federated filesystem protocols in this document define how to construct a namespace accessible by an NFSv4 [RFC3530] or NFSv4.1 [NFSv4.1] client and have been designed to accommodate other file access protocols in the future. The requirements for federated filesystems are described in [FEDFS-REQTS]. A protocol for administering a fileserver's namespace is described in [FEDFS-ADMIN]. In the rest of the document, the term fileserver denotes a fileserver that is part of a federation. 2. Overview of Features and Concepts Lentini, et al. Expires January 11, 2010 [Page 4] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 2.1. Namespace The goal of a unified namespace is to make all managed data available to all clients via the same path in a common filesystem-like namespace. This should be achieved with minimal or zero client configuration. In particular, updates to the common namespace should not require configuration changes at the client. Filesets, which are the unit of data management, are a set of files and directories. From the perspective of the 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 definitions, fileset identifiers, the location of each fileset in the namespace, and the physical location of the implementation(s) of each fileset, 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. 2.2. Fileset and Fileset Name (FSN) A fileset is defined to be a container of data and is the basic unit of data management. Depending on the implementation, they may be anything between an individual directory of an exported filesystem to an entire exported filesystem at a fileserver. A fileset is uniquely represented by its fileset name (FSN). An FSN is considered unique across the federation. An FSN contains information sufficient to locate the namespace database (NSDB) that holds authoritative information about it and an identifier, called the FsnUuid, that identifies it on that NSDB. After an FSN is created, it is associated with a fileset location (FSL) on a fileserver. A fileset can be implemented by one or more FSLs. The attributes of an FSN are: NsdbName: the fully qualified domain name of an NSDB location that contains authoritative information for this FSN. FsnUuid: a 128-bit UUID (universally unique identifier), conforming to [RFC4122], that is used to uniquely identify an FSN. To minimize the probability of two UUIDs colliding, a consistent procedure for generating UUIDs SHOULD be used throughout the federation. Within the federation, UUIDs SHOULD be generated using the procedure described for version 1 of the UUID variant specified in [RFC4122]. An NSDB SHOULD ensure that no two FSNs it stores have the same FsnUuid. Lentini, et al. Expires January 11, 2010 [Page 5] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 2.3. Fileset Location (FSL) An FSL represents the location where the fileset data resides. Each FSL contains the host addresses of the fileserver storing the FSL and protocol specific information for accessing the FSL. Each location has an associated type that determines the protocol(s) that may be used to access its data. Type information can be used to decide the list of locations that will be returned to the client. Each FSL consists of: FslUuid: a 128-bit UUID, conforming to [RFC4122], that is used to uniquely identify an FSL. To minimize the probability of two UUIDs colliding, a consistent procedure for generating UUIDs SHOULD be used throughout the federation. Within the federation, UUIDs SHOULD be generated using the procedure described for version 1 of the UUID variant specified in [RFC4122]. An NSDB SHOULD ensure that no two FSLs it stores have the same FslUuid. FsnUuid: the 128-bit UUID of the FSL's FSN. NsdbName: the fully qualified domain name of an NSDB location that contains authoritative information for this FSL. FSL Host: the fully qualified domain name of the host fileserver storing the physical data FSL TTL: the time in seconds during which the FSL may be cached Annotations: optional 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: optional text descriptions. The semantics of this field are not defined by this document. In addition, an NFS FSL contains information suitable for an NFSv4 fs_locations [RFC3530] or NFSv4.1 fs_locations_info attribute [NFSv4.1]: Pathname: the exported pathname at that host fileserver Major Version: the NFS protocol major version (e.g. 4 for NFSv4.1) Lentini, et al. Expires January 11, 2010 [Page 6] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 Minor Version: the NFS protocol minor version (e.g. 1 for NFSv4.1) Currency: the time lag of this FSL represented as the number of time units it lags the latest version as defined by the NFSv4.1 fs_locations_server's fls_currency field. A currency value of 0 represents the latest version. Currency values are less than or equal to zero Info: as defined by the NFSv4.1 fl_locations_server's fls_info field. Flags: as defined by the NFSv4.1 fs_locations_info's fli_flags field. Valid For: as defined by the NFSv4.1 fs_locations_info's fli_valid_for field. A fileset MAY be accessible by protocols other than NFS. For each such protocol, a corresponding FSL subtype SHOULD be defined. The contents and format of such FSL subtypes are not defined in this document. 2.3.1. Mutual Consistency across Fileset Locations All of the FSLs that have the same FSN (thereby reference the same fileset) are equivalent from the point of view of client access; the different locations of a fileset represent the same data, though potentially at different points in time. Fileset locations are equivalent but not identical. Locations may either be read-only or read-write. Typically, multiple read-write locations are backed by a clustered filesystem while read-only locations are replicas created by a federation-initiated or external replication. 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, all locations exist at the same mount point in the namespace and, thus, one client may be referred to one location while another is directed to a different location. 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 protocol does not guarantee that the different locations are mutually consistent in terms of the currency of the Lentini, et al. Expires January 11, 2010 [Page 7] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 data. It relies on the client file-access protocol (i.e., NFSv4) to contain sufficient information to help the clients determine the currency of the data at each location in order to ensure that the clients do not revert back in time when switching locations. 2.3.2. Caching of Fileset Locations To resolve an FSN to a set of FSL records, the fileserver queries the appropriate NSDB for the FSL records. A fileserver MAY cache these FSL records for a limited period of time. The period of time, if any, during which FSL records are cached is indicated by the FSL's TTL field. The combination of FSL caching and FSL migration presents a challenge. For example, suppose there are three fileservers named A, B, and C and fileserver A contains a junction to fileset X stored on fileserver B. Now suppose that fileset X is migrated from fileserver B to fileserver C and the corresponding FSL information for fileset X in the appropriate NSDB is updated. If fileserver A has a cached FSL for fileset X, a user traversing the junction on fileserver A will be referred to fileserver B even though fileset X has migrated to fileserver C. If fileserver A was not caching FSL records, it would have obtained the correct location of fileset X from the NSDB. Administrators are advised to be aware of FSL caching when performing a migration. When migrating a fileset, administrators SHOULD create a junction at the fileset's old location referring back to the NSDB entry for the fileset. This junction will redirect any users who follow stale FSL information to the correct location. Thus, in the above example, fileserver A would direct clients to fileserver B, but fileserver B would in turn direct clients to fileserver C. Such supplemental junctions (on fileserver B in the example) would not be required to be in place forever. They need to stay in place only until cached FSL entries for the target fileset are invalidated. Each FSL contains a TTL field, a count in seconds of the time interval which is an upper bound for the lifetime of the cached information and a lower bound for the lifetime of the supplemental junctions. For example, suppose this field contains the value 3600 seconds (one hour). In such a case, administrators MUST keep the supplemental junctions in place for at least one hour after the fileset move has taken place, and FSL data MUST NOT be cached by a referring fileserver for more than one hour without a refresh. 2.4. Namespace Database (NSDB) The NSDB service is a federation-wide service that provides interfaces to define, update, and query FSN information and FSN to Lentini, et al. Expires January 11, 2010 [Page 8] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 FSL mapping information. An individual repository of namespace information is called an NSDB location. Each NSDB location is managed by a single administrative entity. A single admin entity can manage multiple NSDB locations. The difference between the NSDB service and an NSDB location is analogous to that between the DNS service and a particular DNS server. Each NSDB location 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 location is authoritative for the filesets that it defines. An NSDB location can cache information from a peer NSDB location. The fileserver can always contact a local NSDB location (if it has been defined) or directly contact any NSDB location to resolve a junction. Each NSDB location supports an LDAP [RFC4510] interface and can be accessed by an LDAP client. 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 LDAP implementations support replication. These features MAY be used to replicate the NSDB. 2.5. Mount Points, Junctions and Referrals A mount point is a directory in a parent fileset where a target fileset may be attached. If a client traverses the path leading from the root of the namespace to the mount point of a target fileset it should be able to access the data in that target fileset (assuming appropriate permissions). The directory where a fileset is mounted is represented by a junction in the underlying filesystem. 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 that is interpreted by the fileserver as a mount point, or by some other mechanism in the underlying filesystem. What data is used by the underlying filesystem to represent the junction is not defined by this protocol. The essential property is that the server must be able to find, given the junction, the FSN for the target fileset. The mechanism by which the server maps a junction to an FSN is outside the scope of this document. The FSN (as described earlier) contains both the the authoritative NSDB location and the FsnUuid (a UUID for the fileset). Lentini, et al. Expires January 11, 2010 [Page 9] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 When a client traversal reaches a junction, the client is referred to a list of FSLs associated with the FSN that was the target of the junction. The client can then redirect its connection to one of the FSLs. This act is called a referral. For NFSv4 and NFSv4.1 clients, the FSL information is returned in the fs_locations and fs_locations_info attributes respectively. 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. 2.6. 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 client mounts the root fileset from any of these designated fileservers it can view a common federation-wide namespace. The properties and schema definition of the root fileset and the protocol details that describe how to configure and replicate the root fileset are not defined in this document. 2.7. Fileservers Fileservers are servers that store the physical fileset data or refer the client to other fileservers. A fileserver can be implemented in a number of different ways, including a single system, a cluster of systems, or some other configuration. A fileserver access to a federated filesystem via NFSv4, NFSv4.1, or some other protocol. 2.8. File-access Clients File access clients are standard off-the-shelf NAS clients that access file data using the NFSv4 protocol, the NFSv4.1 protocol, or some other protocol. 3. Examples In this section we provide examples and discussion of the basic operations facilitated by the federated filesystem protocol: creating a fileset, adding a replica of a fileset, resolving a junction, and creating a junction. Lentini, et al. Expires January 11, 2010 [Page 10] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 3.1. Creating a Fileset and its FSL(s) A fileset is the abstraction of a set of files and their containing directory tree. 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(s) of the implementation of the fileset as FSL(s). 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. 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 1. Choose the NSDB node that will keep track of the FSL(s) and related information for the fileset. 2. Request that the NSDB node register a new FSN for the fileset. 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. Send the FSN, the hostname, the export path, the type, the currency, info, and annotations for the fileset to the NSDB node. The NSDB node records this info and creates the initial FSL for the fileset. Lentini, et al. Expires January 11, 2010 [Page 11] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 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 do not include methods for creating or managing replicas: this is assumed to be a platform- dependent operation (at least at this time). The only interface required is the ability to register or remove the registration of replicas for a fileset. 3.2. Junction Resolution A fileset may contain references to other filesets. These references are represented by junctions. If a client requests access to a fileset object that is a junction, the server resolves the junction to discover the FSL(s) that implements the referenced fileset. There are many possible variations to this procedure, depending on how the junctions are represented and how the information necessary to perform resolution is represented by the server. 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 server determines that the object being accessed is a junction. 2. The server does a local lookup to find the FSN of the target fileset. 3. Using the FSN, the server finds the NSDB node responsible for the target object. 4. The server contacts that NSDB node and asks for the set of FSLs that implement the target FSN. The NSDB node responds with a set of FSLs. 3.3. Example Use Case for Fileset Annotations The 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 snapshot or a weekly snapshot. The different snapshots are mounted at different locations in the namespace. The daily snapshots are Lentini, et al. Expires January 11, 2010 [Page 12] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 considered as a different fileset from the weekly ones but both are related to the source fileset. For this 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]. The federation protocol does not control or manage the relationship among filesets. It merely enables annotating the filesets with user- defined relationships. 4. Mapping the NSDB onto LDAP 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, the new object types, and specifies how the distinguished name (DN) of each object instance MUST be constructed. 4.1. Basic LDAP Configuration The base name (or suffix) of the NSDB directory information tree (DIT) is "o=fedfs". The DN of the privileged LDAP user is, by convention, "cn=admin,o=fedfs". This user is able to modify the contents of the LDAP database. It is permitted to use a different DN (or add additional privileged users) but if a different DN is used then every admin entity that needs to modify the contents of the database or view privileged information must be made aware of the new DN. It MUST be possible for the anonymous (unauthenticated) user to perform LDAP queries that access the NSDB data. All implementations SHOULD use the same schema, or, at minimum, a schema that includes all of the objects, with each of the attributes, named in the following sections. Lentini, et al. Expires January 11, 2010 [Page 13] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 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: #!/bin/sh grep '^ *///' | sed 's?^ */// ??' | sed 's?^ *///$??' 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: sh extract.sh < spec.txt > fedfs.schema The effect of the script is to remove leading white space from each line, plus a sentinel sequence of "///". 4.2.1. LDAP Attributes This section describes the required attributes of the NSDB LDAP schema. 4.2.1.1. fedfsUuid A fedfsUuid is the base type for all of the universally unique identifiers (UUIDs) used by the federated filesystem protocols. This SHOULD be defined in terms of the text representation of the standard UUID (as defined in [RFC4122]). It MAY also be useful, for purposes of debugging or annotation, to permit a fedfsUuid to include members of a more general class of strings. A fedfsUuid is a single-valued LDAP attribute. It is formally Lentini, et al. Expires January 11, 2010 [Page 14] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 defined as follows: /// /// attributetype ( /// 1.3.6.1.4.1.31103.1.1 NAME 'fedfsUuid' /// DESC 'A UUID used by NSDB' /// SUP name /// SINGLE-VALUE /// ) /// 4.2.1.2. fedfsNetAddr A fedfsNetAddr is the locative name of a network service. It MUST be a UTF-8 string and represent a network location in either IPv4, IPv6, or DNS host name notation. The format is the same as that specified for an fs_location4's server array elements in section 11.9 of [NFSv4.1]. This attribute is single-valued. It is formally defined as follows: /// /// attributetype ( /// 1.3.6.1.4.1.31103.1.2 NAME 'fedfsNetAddr' /// DESC 'The network name of a host or service' /// SUP name /// SINGLE-VALUE /// ) /// 4.2.1.3. fsnUuid A fsnUuid represents the fsnUuid component of an FSN. The fsnUuid is a subclass of fedfsUuid. This attribute is single-valued. /// /// attributetype ( /// 1.3.6.1.4.1.31103.1.3 NAME 'fsnUuid' /// DESC 'The FSN UUID component of an FSN' /// SUP fedfsUuid /// SINGLE-VALUE /// ) /// Lentini, et al. Expires January 11, 2010 [Page 15] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 4.2.1.4. nsdbName An nsdbName is the NSDB component of an FSN. The nsdbName attribute is a subclass of fedfsNetAddr. This attribute is single-valued. /// /// attributetype ( /// 1.3.6.1.4.1.31103.1.4 NAME 'nsdbName' /// DESC 'The NSDB location component of an FSN' /// SUP fedfsNetAddr /// SINGLE-VALUE /// ) /// 4.2.1.5. fslUuid Each FSL must have a UUID associated with it, which serves as part of its DN. The fslUuid attribute is a subclass of fedfsUuid. This attribute is single-valued. /// /// attributetype ( /// 1.3.6.1.4.1.31103.1.5 NAME 'fslUuid' /// DESC 'UUID of an FSL' /// SUP fedfsUuid /// SINGLE-VALUE /// ) /// 4.2.1.6. fslHost An fslHost is the hostname/port component of an FSL. The fslHost attribute is a subclass of fedfsNetAddr. This attribute is single-valued. Lentini, et al. Expires January 11, 2010 [Page 16] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 /// /// attributetype ( /// 1.3.6.1.4.1.31103.1.6 NAME 'fslHost' /// DESC 'Service location for a fileserver' /// SUP fedfsNetAddr /// SINGLE-VALUE /// ) /// 4.2.1.7. fslTTL An fslTTL is the amount of time in seconds an FSL SHOULD be cached by a fileserver. The numeric fslTTL value should be converted to a string and encoded as a UTF-8 string. This attribute is single-valued. /// /// attributetype ( /// 1.3.6.1.4.1.31103.1.7 NAME 'fslTTL' /// DESC 'Time to live of an FSL' /// SUP name /// SINGLE-VALUE /// ) /// 4.2.1.8. fslNfsPath The path component of an FSL encoded as a UTF-8 string. This attribute is single-valued. /// /// attributetype ( /// 1.3.6.1.4.1.31103.1.8 NAME 'fslNfsPath' /// DESC 'Server-local path to a fileset' /// SUP name /// SINGLE-VALUE /// ) /// 4.2.1.9. fslNfsMajorVer The NFS major version of the associated NFS FSL. The numeric fslTTL value should be converted to a string and encoded as a UTF-8 string. For example if the FSL was exported via NFS 4.1, the contents of this attribute would be the value 4. Lentini, et al. Expires January 11, 2010 [Page 17] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 This attribute is single-valued. /// /// attributetype ( /// 1.3.6.1.4.1.31103.1.9 NAME 'fslNfsMajorVer' /// DESC 'NFS major version' /// SUP name /// SINGLE-VALUE /// ) /// 4.2.1.10. fslNfsMinorVer The NFS minor version of the associated NFS FSL. The numeric fslTTL value should be converted to a string and encoded as a UTF-8 string. For example if the FSL was exported via NFS 4.1, the contents of this attribute would be the value 1. This attribute is single-valued. /// /// attributetype ( /// 1.3.6.1.4.1.31103.1.10 NAME 'fslNfsMinorVer' /// DESC 'NFS minor version' /// SUP name /// SINGLE-VALUE /// ) /// 4.2.1.11. fslNfsCurrency The currency of an FSL. The signed 32-bit numeric value should be converted to a string encoded as a UTF-8 string. This attribute is used to populate the NFSv4.1 fs_locations_server's currency field. This attribute is single-valued. /// /// attributetype ( /// 1.3.6.1.4.1.31103.1.11 NAME 'fslNfsCurrency' /// DESC 'up-to-date measure of the data' /// SUP name /// SINGLE-VALUE /// ) /// Lentini, et al. Expires January 11, 2010 [Page 18] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 4.2.1.12. fslNfsInfo Information about the FSL. The variable sized array of octets is stored directly in this attribute. This attribute is used to populate the NFSv4.1 fs_locations_server's info field. This attribute is single-valued. /// /// attributetype ( /// 1.3.6.1.4.1.31103.1.12 NAME 'fslNfsInfo' /// DESC 'Information about the FSL' /// EQUALITY octetStringMatch /// SYNTAX 1.3.6.1.4.1.1466.115.121.1.40 /// SINGLE-VALUE /// ) /// 1.3.6.1.4.1.1466.115.121.1.40 refers to the Octet String syntax [RFC4517]. 4.2.1.13. fslNfsFlags An NFS FSL's flags. The unsigned 32-bit numeric value should be converted to a string encoded as a UTF-8 string. This attribute is used to populate the NFSv4.1 fs_locations_info's fli_flags field. This attribute is single-valued. /// /// attributetype ( /// 1.3.6.1.4.1.31103.1.13 NAME 'fslNfsFlags' /// DESC 'Flags' /// SUP name /// SINGLE-VALUE /// ) /// 4.2.1.14. fslNfsValidFor An NFS FSL's "valid for" flag. The signed 32-bit numeric value should be converted to a string encoded as a UTF-8 string. This attribute is used to populate the NFSv4.1 fs_locations_info's Lentini, et al. Expires January 11, 2010 [Page 19] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 fli_valid_for field. This attribute is single-valued. /// /// attributetype ( /// 1.3.6.1.4.1.31103.1.14 NAME 'fslNfsValidFor' /// DESC 'Valid for time' /// SUP name /// SINGLE-VALUE /// ) /// 4.2.1.15. annotation An annotation of an object. This attribute is multi-valued; an object type that permits annotations may have any number of annotations per instance. /// /// attributetype ( /// 1.3.6.1.4.1.31103.1.15 NAME 'annotation' /// DESC 'Annotation of an object' /// SUP name /// ) /// An annotation attribute MUST be an UTF-8 string formatted as follows: "KEY" = "VAL" White space, defined as space, form-feed ('\f'), newline ('\n'), carriage return ('\r'), horizontal tab ('\t'), and vertical tab ('\v') characters, is ignored. KEY and VAL MAY may contain any UTF-8 characters. The following escape sequences are allowed: +-----------------+-------------+ | escape sequence | replacement | +-----------------+-------------+ | \\ | \ | | \" | " | +-----------------+-------------+ An annotation attribute that does not adhere to this format SHOULD be ignored. Lentini, et al. Expires January 11, 2010 [Page 20] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 The following are examples of valid annotation attributes: "key1" = "foo" "another key" = "x=3" "key-2" = "A string with \" and \\ characters." which correspond to the following key/value pairs: +-------------+-----------------------------------+ | key | value | +-------------+-----------------------------------+ | key1 | foo | | another key | x=3 | | key-2 | A string with " and \ characters. | +-------------+-----------------------------------+ 4.2.1.16. descr This attribute is used to store an object's description encoded as a UTF-8 string. This attribute is multi-valued which permits any number of descriptions per entry. /// /// attributetype ( /// 1.3.6.1.4.1.31103.1.16 NAME 'descr' /// DESC 'Description of an object' /// SUP name /// ) /// 4.2.2. LDAP Objects 4.2.2.1. fedfsFsn A fedfsFsn represents an FSN. The required attributes of a fedfsFsn are an nsdbName and fsnUuid. A fedfsFsn's annotation and descr attributes are OPTIONAL. The DN of an FSN is REQUIRED to take the following form: "fsnUuid=FSNUUID,o=fedfs", where FSNUUID is the UUID of the FSN. Since LDAP requires a DN to be unique, this ensures that each FSN entry has a unique UUID value within the LDAP directory. A fedfsFsn MAY also have additional attributes, but these attributes Lentini, et al. Expires January 11, 2010 [Page 21] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 MUST NOT be referenced by any part of this document. /// /// objectclass ( /// 1.3.6.1.4.1.31103.1.1001 NAME 'fedfsFsn' /// DESC 'Represents a fileset' /// SUP top STRUCTURAL /// MUST ( /// fsnUuid /// $ nsdbName /// ) /// MAY ( /// annotation /// $ descr /// )) /// 4.2.2.2. fedfsFsl The fedfsFsl object class represents an FSL. A fedfsFsl's required attributes are an fslUuid, fsnUuid, nsdbName, fslHost, and fslTTL. A fedfsFsl's annotation and descr attributes are OPTIONAL. 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 below is used to record an NFS FSL's location. Other subtypes MAY be defined for other protocols (e.g. CIFS). The DN of an FSL is REQUIRED to take the following form: "fslUuid=FSLUUID,fsnUuid=FSNUUID,o=fedfs" where FSLUUID and FSNUUID are the UUIDs of the FSL and its FSN respectively. Since LDAP requires a DN to be unique, this ensures that each FSL entry has a unique UUID value within the LDAP directory. Lentini, et al. Expires January 11, 2010 [Page 22] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 /// /// objectclass ( /// 1.3.6.1.4.1.31103.1.1002 NAME 'fedfsFsl' /// DESC 'A physical location of a fileset' /// SUP top ABSTRACT /// MUST ( /// fslUuid /// $ fsnUuid /// $ nsdbName /// $ fslHost /// $ fslTTL /// ) /// MAY ( /// annotation /// $ descr /// )) /// 4.2.2.3. 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: "fslUuid=FSLUUID,fsnUuid=FSNUUID,o=fedfs" where FSLUUID and FSNUUID are the UUIDs of the FSL and its FSN respectively. Since LDAP requires a DN to be unique, this ensures that each NFS FSL entry has a unique UUID value within the LDAP directory. /// /// objectclass ( /// 1.3.6.1.4.1.31103.1.1003 NAME 'fedfsNfsFsl' /// DESC 'A NFS location of a fileset' /// SUP fedfsFsl STRUCTURAL /// MUST ( /// fslNfsPath /// $ fslNfsMajorVer /// $ fslNfsMinorVer /// $ fslNfsCurrency /// $ fslNfsInfo /// $ fslNfsFlags /// $ fslNfsValidFor /// )) /// Lentini, et al. Expires January 11, 2010 [Page 23] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 5. NSDB Operations The operations defined by the protocol can be described as several sub-protocols that are used by entities within the federation to perform different roles. The first of these sub-protocols defines how the state of an NSDB location 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 location in order to perform resolution (or to find other information about the data stored within that NSDB location) and the responses returned by the NSDB location. 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 location 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 location implement a complete LDAP service, and therefore we define in these sections the minimum level of LDAP functionality required to implement an NSDB location. The NSDB sub-protocols are defined in the next two sub-sections. 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 ONC RPC protocols. The reason for using ONC RPC 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 [FEDFS-ADMIN]. 5.1. NSDB Operations for Administrators The admin entity initiates and controls the commands to manage fileset and namespace information. The admin entity, however, is stateless. All state is maintained at the NSDB locations or at the Lentini, et al. Expires January 11, 2010 [Page 24] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 fileserver. We require that each NSDB location be able to act as an LDAP server and that the protocol used for communicating between the admin entity and each NSDB location is LDAP. 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. In the description of the LDAP messages and LDIF, we use the following notation: constant strings and literal names are specified in lower or mixed case, while variables or values are specified in uppercase. 5.1.1. Create an FSN The administrator uses this operation to create a new FSN by requesting the NSDB to create a new fedfsFsn in its LDAP database with an fsnUuid value of FSNUUID and an NsdbName value of NSDBNAME. The NSDB location that receives the request SHOULD check that the NSDBNAME matches its own value and return an error if it does not. This is to ensure that an FSN is always created by the NSDB location encoded within the FSN as its owner. The NSDB location that receives the request SHOULD check all of the attributes for validity and consistency, but this is not generally possible for LDAP servers because the consistency requirements cannot be expressed in the LDAP schema (although many LDAP servers can be extended, via plug-ins or other mechanisms, to add functionality beyond the strict definition of LDAP). 5.1.1.1. LDAP Request The admin chooses the fsnUuid and NsdbName of the FSN. The fsnUuid is a UUID and should be chosen via a standard process for creating a UUID (described in [RFC4122]). The NsdbName is the name of the NSDB location that will serve as the source of definitive information about an FSN for the life of that FSN. In the example below, the admin server chooses a fsnUuid of FSNUUID and the NsdbName of NSDBNAME and then sends an LDAP ADD request, described by the LDIF below, to the NSDB location NSDBNAME. This will create a new fedfsFsn on that NSDB location with the given attributes in the LDAP database. Lentini, et al. Expires January 11, 2010 [Page 25] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 dn: fsnUuid=FSNUUID,o=fedfs changeType: add objectClass: fedfsFsn fsnUuid: FSNUUID nsdbName: NSDBNAME 5.1.2. Delete an FSN This operation deletes the given fileset name. 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 only removes the fileset from the namespace (by removing the records for that FSN from the NSDB location 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 client tries to resolve the target of a junction that refers to the deleted FSN and the NSDB returns an error. 5.1.2.1. LDAP Request The admin sends an LDAP DELETE request to the NSDB server to remove the fedfsFsn from the NSDB server. An example LDIF for the delete request is shown below. dn: fsnUuid=FSNUUID,o=fedfs changeType: delete 5.1.3. Create an FSL This operations creates a new Fileset location at the given location denoted by HOST and PATH for the given FSN. Normally an FSL is identified by the HOST:PATH pair. A UUID is an optional way to identify an FSL if it is recovered to a different HOST:PATH after a backup/restore. The FSL create command will result in the admin server sending an LDAP ADD request to create a new fedfsFsl at the NSDB maintaining the given FSN. The example LDIF is shown below. The PATH is the pathname where the fileset is located on the fileserver HOST. Lentini, et al. Expires January 11, 2010 [Page 26] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 5.1.3.1. LDAP Request The admin sends an LDAP ADD request to the NSDB server to add the FSL. An example LDIF for adding an NFS FSL is shown below. dn:fslUuid=UUID,fsnUuid=FSNUUID,o=fedfs changeType: add objectClass: fedfsNfsFsl fslUuid: UUID fsnUuid: FSNUUID nsdbName: NSDBNAME fslHost: HOST fslTTL: TTL fslNfsPath: PATH fslNfsMajorVer: MAJOR fslNfsMinorVer: MINOR fslNfsCurrency: CURRENCY fslNfsInfo: INFO fslNfsFlags: FLAGS fslNfsValidFor: TIME annotation: ANNOTATION descr: DESCR 5.1.4. Delete an FSL This operation deletes the given Fileset location. The admin requests the NSDB location storing the fedfsFsl to delete it from its database. This operation does not result in the fileset location's data being deleted at the fileserver. 5.1.4.1. LDAP Request The admin sends an LDAP DELETE request to the NSDB server to remove the FSL. dn: fslUuid=UUID,fsnUuid=FSNUUID,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 server maintaining this FSL. The attributes that must not change are the fslUuid and the fsnUuid of the fileset this FSL implements. Lentini, et al. Expires January 11, 2010 [Page 27] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 5.1.5.1. LDAP Request The admin sends an LDAP MODIFY request to the NSDB server to update the FSL. dn: fslUuid=UUID,fsnUuid=FSNUUID,o=fedfs changeType: modify replace: ATTRIBUTE-TYPE 5.2. NSDB Operations for Fileservers 5.2.1. Lookup FSLs for an FSN Using an LDAP search, the fileserver can obtain all of the FSLs for a given FSN. The FSN's fsnUuid is used as the search key. To obtain a list of all FSLs, the following search can be used: LDAP Request Search base: fsnUuid=FSNUUID, o=fedfs Search scope: onelevel Search filter: (objectClass=fedfsFsl) This search is for the children of the object with DN "fsnUuid=FSNUUID,o=fedfs" with a filter for "objectClass = fedfsFsl". (If you want to be doubly careful, you can also filter by the nsdbName.) The following search can be used to obtain only the NFS FSLs: LDAP Request Search base: fsnUuid=FSNUUID, o=fedfs Search scope: onelevel Search filter: (objectClass=fedfsNfsFsl) This also searches for the children of the object with DN "fsnUuid=FSNUUID,o=fedfs", but the filter for "objectClass = fedfsNfsFsl" restricts the results to only NFS FSLs. (If you want to be doubly careful, you can also filter by the nsdbName.) The fileserver can present the search results in a format useful to the type of the client on whose behalf the fileserver is performing the request. For an NFS client, the fileserver can use the search Lentini, et al. Expires January 11, 2010 [Page 28] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 results to construct an NFSv4 fs_locations list or NFSv4.1 fs_locations_info list. 6. Security Considerations Both LDAP and NFSv4/NFSv4.1 provide security mechanisms. When used in conjunction with the federated filesystem protocols described in this document, the use of these mechanisms is RECOMMENDED. Specifically, the use of RPCSEC_GSS [RFC2203] [RFC2743] is RECOMMENDED on all connections between a client and fileserver. For all LDAP connections established by the federated filesystem protocols, TLS [RFC5246] [RFC4513] is RECOMMENDED. Within a federation, there are two components that an attacker may be able to compromise: a fileserver and an NSDB. If an attacker compromises a fileserver, the attacker can interfere with the client's filesystem I/O operations (e.g. by returning fictitious data in the response to a read request) or fabricating a referral. The attacker's abilities are the same regardless of whether or not the federation protocols are in use. 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 which query it. It should be noted that the federation protocols do not directly provide access to filesystem data. The federation protocols only provide a mechanism for building a namespace. All data transfers occur between a client and server 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 file server to act as a proxy for a client. 7. IANA Considerations The LDAP attributes and object classes defined in this document are assigned object identifier (OID) values from the 1.3.6.1.4.1.31103.x range. This is an Internet Private Enterprise Numbers range and was assigned to the authors using the process described in [RFC2578]. In accordance with Section 3.4 and Section 4 of [RFC4520], the object identifier descriptors defined in this document (listed below) will be registered via the Expert Review process. Lentini, et al. Expires January 11, 2010 [Page 29] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 7.1. LDAP Descriptor Registration Subject: Request for LDAP Descriptor Registration Person & email address to contact for further information: See "Author/Change Controller" Specification: draft-ietf-nfsv4-federated-fs-protocol Author/Change Controller: [document authors] Object Identifier: 1.3.6.1.4.1.31103.1.1 Descriptor (short name): fedfsUuid Object Identifier: 1.3.6.1.4.1.31103.1.2 Descriptor (short name): fedfsNetAddr Object Identifier: 1.3.6.1.4.1.31103.1.3 Descriptor (short name): fsnUuid Object Identifier: 1.3.6.1.4.1.31103.1.4 Descriptor (short name): nsdbName Object Identifier: 1.3.6.1.4.1.31103.1.5 Descriptor (short name): fslUuid Object Identifier: 1.3.6.1.4.1.31103.1.6 Descriptor (short name): fslHost Object Identifier: 1.3.6.1.4.1.31103.1.7 Descriptor (short name): fslTTL Object Identifier: 1.3.6.1.4.1.31103.1.8 Descriptor (short name): fslNfsPath Object Identifier: 1.3.6.1.4.1.31103.1.9 Descriptor (short name): fslNfsMajorVer Object Identifier: 1.3.6.1.4.1.31103.1.10 Descriptor (short name): fslNfsMinorVer Object Identifier: 1.3.6.1.4.1.31103.1.11 Descriptor (short name): fslNfsCurrency Object Identifier: 1.3.6.1.4.1.31103.1.12 Descriptor (short name): fslNfsInfo Lentini, et al. Expires January 11, 2010 [Page 30] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 Object Identifier: 1.3.6.1.4.1.31103.1.13 Descriptor (short name): fslNfsFlags Object Identifier: 1.3.6.1.4.1.31103.1.14 Descriptor (short name): fslNfsValidFor Object Identifier: 1.3.6.1.4.1.31103.1.15 Descriptor (short name): annotation Object Identifier: 1.3.6.1.4.1.31103.1.16 Descriptor (short name): descr Object Identifier: 1.3.6.1.4.1.31103.1.1001 Descriptor (short name): fedfsFsn Object Identifier: 1.3.6.1.4.1.31103.1.1002 Descriptor (short name): fedfsFsl Object Identifier: 1.3.6.1.4.1.31103.1.1003 Descriptor (short name): fedfsNfsFsl 8. Glossary Administrator: 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. Client: Any client that accesses the fileserver data using a supported filesystem access protocol. Federation: A set of server collections and singleton servers that use a common set of interfaces and protocols in order to provide to their clients a federated namespace accessible through a filesystem access protocol. Fileserver: A server exporting a filesystem via a network filesystem access protocol. Fileset: The abstraction of a set of files and their containing directory tree. 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 filesystems. Lentini, et al. Expires January 11, 2010 [Page 31] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 Filesystem: 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 filesystem, nor at the export point for the filesystem. A single filesystem MAY implement more than one fileset, if the client protocol and the fileserver permit this. Filesystem access protocol: A network filesystem access protocol such as NFSv2 [RFC1094], NFSv3 [RFC1813], NFSv4 [RFC3530], or CIFS. FSL (Fileset location): The location of the implementation of a fileset at a particular moment in time. A FSL MUST be something that can be translated into a protocol-specific description of a resource that a client can access directly, such as a fs_location (for NFSv4), or share name (for CIFS). Note that not all FSLs need to be explicitly exported as long as they are contained within an exported path on the fileserver. 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 filesystem 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 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 info) that implement a given partition of the FSNs. Referral: A server response to a 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. Lentini, et al. Expires January 11, 2010 [Page 32] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 Replica: A replica is 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, and 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 [FEDFS-ADMIN] Lentini, J., Everhart, C., Ellard, D., Tewari, R., and M. Naik, "Administration Protocol for Federated Filesystems", draft-ietf-nfsv4-federated-fs-admin (Work In Progress), 2008. [FEDFS-REQTS] Lentini, J., Everhart, C., Ellard, D., Tewari, R., and M. Naik, "Requirements for Federated File Systems", draft-ietf-nfsv4-federated-fs-reqts (Work In Progress), 2008. [NFSv4.1] Shepler, S. and M. Eisler, "NFS Version 4 Minor Version 1", draft-ietf-nfsv4-minorversion1 (Work In Progress), 2008. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2203] Eisler, M., Chiu, A., and L. Ling, "RPCSEC_GSS Protocol Specification", RFC 2203, September 1997. Lentini, et al. Expires January 11, 2010 [Page 33] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 [RFC2578] McCloghrie, K., Ed., Perkins, D., Ed., and J. Schoenwaelder, Ed., "Structure of Management Information Version 2 (SMIv2)", STD 58, RFC 2578, April 1999. [RFC2743] Linn, J., "Generic Security Service Application Program Interface Version 2, Update 1", RFC 2743, January 2000. [RFC3530] Shepler, S., Callaghan, B., Robinson, D., Thurlow, R., Beame, C., Eisler, M., and D. Noveck, "Network File System (NFS) version 4 Protocol", RFC 3530, April 2003. [RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally Unique IDentifier (UUID) URN Namespace", RFC 4122, July 2005. [RFC4510] Zeilenga, K., "Lightweight Directory Access Protocol (LDAP): Technical Specification Road Map", RFC 4510, June 2006. [RFC4511] Sermersheim, J., "Lightweight Directory Access Protocol (LDAP): The Protocol", RFC 4511, June 2006. [RFC4512] Zeilenga, K., "Lightweight Directory Access Protocol (LDAP): Directory Information Models", RFC 4512, June 2006. [RFC4513] Harrison, R., "Lightweight Directory Access Protocol (LDAP): Authentication Methods and Security Mechanisms", RFC 4513, June 2006. [RFC4517] Legg, S., "Lightweight Directory Access Protocol (LDAP): Syntaxes and Matching Rules", RFC 4517, June 2006. [RFC4520] Zeilenga, K., "Internet Assigned Numbers Authority (IANA) Considerations for the Lightweight Directory Access Protocol (LDAP)", BCP 64, RFC 4520, June 2006. [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, August 2008. 9.2. Informational References [AFS] Howard, J., "An Overview of the Andrew File System", Proceeding of the USENIX Winter Technical Conference , 1988. [RFC1094] Nowicki, B., "NFS: Network File System Protocol specification", RFC 1094, March 1989. Lentini, et al. Expires January 11, 2010 [Page 34] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 [RFC1813] Callaghan, B., Pawlowski, B., and P. Staubach, "NFS Version 3 Protocol Specification", RFC 1813, June 1995. [RFC3254] Alvestrand, H., "Definitions for talking about directories", RFC 3254, April 2002. Appendix A. Acknowledgments We would like to thank Andy Adamson of NetApp, Paul Lemahieu of EMC, Robert Thurlow of Sun Microsystems, and Mario Wurzl of EMC for helping to author this document. We would also like to thank George Amvrosiadis for pointing out that several LDAP attributes were missing the SINGLE-VALUE keyword in a draft version of this document. Authors' Addresses James Lentini NetApp 1601 Trapelo Rd, Suite 16 Waltham, MA 02451 US Phone: +1 781-768-5359 Email: jlentini@netapp.com Craig Everhart NetApp 7301 Kit Creek Rd Research Triangle Park, NC 27709 US Phone: +1 919-476-5320 Email: everhart@netapp.com Lentini, et al. Expires January 11, 2010 [Page 35] Internet-Draft NSDB Protocol for Federated Filesystems July 2009 Daniel Ellard BBN Technologies 10 Moulton Street Cambridge, MA 02138 US Phone: +1 617-873-8000 Email: dellard@bbn.com Renu Tewari IBM Almaden 650 Harry Rd San Jose, CA 95120 US Email: tewarir@us.ibm.com Manoj Naik IBM Almaden 650 Harry Rd San Jose, CA 95120 US Email: manoj@almaden.ibm.com Lentini, et al. Expires January 11, 2010 [Page 36]