NFSv4 R. Tewari Internet Draft M. Naik Intended status: Standards Track IBM Expires: June 2008 D. Ellard C. Everhart Network Appliance December 12, 2007 Protocol for Federated Filesystems v1.0 draft-tewari-nfsv4-federated-fs-protocol-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. This document may not be modified, and derivative works of it may not be created, except to publish it as an RFC and to translate it into languages other than English. 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 June 12, 2008. Copyright Notice Copyright (C) The IETF Trust (2007). Tewari, et al. Expires June 12, 2008 [Page 1] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 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 and collections of 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. Expires June 12, 2008 [Page 2] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 1 Introduction.....................................................5 1.1 Protocol Goals.............................................5 2 Overview of Features and Concepts................................6 2.1 Namespace..................................................6 2.2 Fileset....................................................6 2.2.1 Fileset Location (FSL)...............................6 2.3 Namespace Repository (NSDB)................................8 2.4 Mount Points, Junctions and Referrals......................8 2.5 Federation Root FileServers................................9 2.6 Federation Root FileSet....................................9 2.7 Fileservers................................................9 2.8 File-access Clients........................................9 3 Interaction with NFSv4...........................................9 4 Finding the local NSDB...........................................10 5 Examples.........................................................10 5.1 Create a Fileset and its FSL(s)............................10 5.1.1 Creating a Fileset and a FSN.........................10 5.1.2 Adding a Replica of a Fileset........................11 5.2 Junction Resolution........................................11 5.3 Example use case for fileset annotations...................12 6 Error Definitions................................................12 7 Protocol Operations..............................................13 7.1 ADMINISTRATIVE NSDB OPERATIONS.............................14 7.1.1 FSN_CREATE............................................15 7.1.2 FSN_DELETE............................................16 7.1.3 FSN_MOUNT.............................................17 7.1.4 FSN_UNMOUNT...........................................18 7.1.5 FSL_CREATE ...........................................19 7.1.6 FSL_DELETE...........................................20 7.1.7 FSL_UPDATE...........................................20 7.1.8 FSL_STAT.............................................21 7.2 FILESERVER to NSDB OPERATIONS..............................21 7.2.1 FSN_GET_FSL..........................................21 7.3 ADMIN to FILESERVER OPERATIONS.............................22 7.3.1 FSL_FINDBYHOST, FSN_FINDBYHOST, FSL_FINDBYHOSTPATH,.......24 7.3.2 FSN_CREATE_JUNCTION.........................................24 7.3.3 FSN_CREATE_EXPORT....................................25 8 Security Considerations..........................................25 9 IANA Considerations..............................................25 10 Conclusions...................................................25 11 Glossary......................................................25 Appendix B. Namespace Schema Class Objects..........................28 12 References....................................................30 12.1 Normative References.......................................30 Expires June 12, 2008 [Page 3] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 Author's Addresses..................................................31 Intellectual Property Statement.....................................32 Disclaimer of Validity..............................................32 Expires June 12, 2008 [Page 4] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 RFC 2119 Keywords 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 RFC-2119 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 (and possibly across multiple enterprises) with reasonably good performance. The first requirement of a federated filesystem is the ability to traverse the data exported by different fileservers without requiring a static client configuration. The second requirement is that the location of the data should be dynamically discovered and the discovery process should be transparent to the clients. The third requirement is that it should be possible for all clients, with sufficient privilege, to view the same namespace regardless of the fileserver they connect to. Traditionally, fileserver collections are administered by a single entity. 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. Relying on vendor-proprietary tools does not work in larger enterprises or when collaborating across enterprises because it is likely that the system will contain fileservers running different software, each with their own interfaces, with no common protocol to manage the namespace or exchange namespace information. There may also be independently-administered singleton servers that export some or all of their filesystem resources. A filesystem federation protocol enables the interoperation across multi-vendor fileservers managed by the same administrative entity, across singleton independent fileservers, and across independent administrative entities that may manage a collection of fileservers. The scope of the filesystem federation protocol is limited to NFSv4 capable fileservers. The support for NFSv3 fileservers is optional. 1.1 Protocol Goals The objective of this draft is to specify a set of interfaces by which fileservers and collections of fileservers with different administrators can form a fileserver federation that provides a namespace composed of the filesystems physically hosted on and exported by the fileservers of the federation. It should be possible, using a system that implements the interfaces, to share a common namespace across all the fileservers in the federation. It should also be possible for different fileservers in the federation to project different namespaces and enable clients to traverse them. Such 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. Such a federation may also have an arbitrary number of administrative entities responsible for administering disjoint subsets of the fileservers. In the rest of the document the term fileserver implies a fileserver that is part of the federation. A fileserver not part of the federation is called an external fileserver. Expires June 12, 2008 [Page 5] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 2 Overview of Features and Concepts 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 accessible from a single mount. Depending on the implementation, they may be anything between an individual directory of an exported filesystem to an entire exported filesystem at a fileserver. From the perspective of the clients, the common namespace is constructed by logically 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 that should permit traversal into another namespace at defined junction points. 2.2 Fileset A fileset is defined to be a container of data and is the basic unit of data management. It is uniquely represented by the fileset name (FSN). An FSN is considered unique across the federation. An FSN contains information sufficient to locate the namespace repository (NSDB) that holds authoritative information about it and an identifier, called fsn_uuid, 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 RFC 4122, that is used to uniquely identify an FSN. 2.2.1 Fileset Location (FSL) An FSL represents the location where the fileset data resides. Each FSL maps to a host:path pair on a file server. An FSL may also have additional attributes. 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. It also has associated status information. Other attributes associated with an FSL are based on the NFSv4.1 fs_locations_info attribute[RFCTBD]. Expires June 12, 2008 [Page 6] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 struct FSL { utf8string host_fqdn; utf8string pathname; FSL_ATTR attrs; }; Each FSL consists of: host_fqdn: the name of the host fileserver storing the physical data pathname: the exported pathname at that host fileserver attrs: additional attributes for this FSL, as described in the FSL_ATTR structure struct FSL_ATTR { protocol_t type; int32_t currency; annotation_t annotations<>; fs_status_t status; opaque_t info<>; } The attributes associated with each FSL are: type: the protocol(s) supported by the fileserver hosting this FSL. 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_info attribute. A currency value of 0 represents the latest version. Currency values are <= 0. annotations: a list of name/value pairs that can be interpreted by an individual NSDB. The semantics of the name/value pair is not defined by this protocol and is intended to be used by higher-level administration protocols. status: fls_status as defined by the NFSv4.1 status attribute. info: as defined in NFSv4.1 fs_locations_info attribute. 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 Expires June 12, 2008 [Page 7] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 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 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. This raises a concern for NFSv3 fileservers, which the federation protocol may support, that may lack such control. 2.3 Namespace Repository (NSDB) The NSDB service is a federation-wide service that provides interfaces to define, update, and query FSN information and FSN to 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. The term local NSDB is shorthand for an NSDB location that is known a priori to a server. It is typically located within the same federation member as the server, but this is not required. A local NSDB is not required. 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 interface and can be accessed by an LDAP client. 2.4 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 fileset it should be able to access the data in that 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 file system. What data is used by the underlying file system 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 FSN (as described earlier) contains both the NSDB location of the authoritative NSDB location and the FsnUuid (a UUID for the fileset). Expires June 12, 2008 [Page 8] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 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 clients, the FSL information is returned in the fs_locations or fs_locations_info attributes. The federation-fs interfaces 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. 2.5 Federation Root FileServers A set of designated fileservers that render the common federation-wide namespace are called the federation root fileservers. The federation protocol does not mandate that federation root fileservers be defined. When a client mounts the root of the namespace from a root fileserver it can traverse the entire federation-wide namespace. It is not required for a client to mount from one of the root fileservers. If a client mounts from a non-root fileserver then it can traverse the part of the namespace that is visible starting from that fileserver. A client can mount multiple individual filesets from multiple non-root fileservers and chose to navigate the namespace in any manner. How the client discovers the root fileserver(s), if one is defined, is not in the scope of the federation protocol. Numerous external techniques such as DNS SRV records can be used for this. 2.6 Federation Root FileSet The root fileset is the optional, top-level fileset of the federation-wide namespace. The root of the namespace is the top level directory of this fileset. The fileset can contain an arbitrary number of virtual directories. The leaf directories of the root fileset serve as the mount points for other filesets. It is desirable that the leaf directories not contain data. The root fileset is a simple combination of internal nodes and leaf nodes where each leaf node is a junction to a target fileset. The root fileset is replicated at all the root fileservers. The recommended replication protocols for root fileset replication are: an external protocol such as rsync or NDMP. 2.7 Fileservers Fileservers are NFSv4 servers that store the physical fileset data or fileservers that refer the client to other fileservers. 2.8 File-access Clients File access clients are standard off-the-shelf NAS clients that access file data using the NFSv4 protocol. 3 Interaction with NFSv4 The federation protocol is compatible with the requirements of NFSv4 referral mechanisms as defined in RFC 3530. Expires June 12, 2008 [Page 9] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 4 Finding the local NSDB The local NSDB may be used for finding the mapping from the server's local representation of a junction to an FSN. How the mapping is resolved is implementation-specific. The fed-fs protocol does not mandate how and if a local NSDB is defined or located. A fileserver could choose to have a special configuration setup for defining the local or default NSDB in a manner similar to a resolv.conf file for DNS. 5 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. 5.1 Create 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. 5.1.1 Creating a Fileset and a 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 may either be chosen by the NSDB node or by the server. The latter case is used if the fileset is being restored, perhaps as part of disaster recovery, and the server wishes to specify the FSN in order to permit existing junctions that reference that FSN to work again. At this point, the FSN exists, but its location is unspecified. Expires June 12, 2008 [Page 10] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 3. Send the FSN, the local volume path, the export path, and the export options for the local implementation of the fileset to the NSDB node. Annotations about the FSN or the location may also be sent. The NSDB node records this info and creates the initial FSL for the fileset. 5.1.2 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 interfaces 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. 5.2 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. In this example, we assume that the only thing directly expressed by the junction is the junction key; its mapping to FSN can be kept local to the server hosting the junction. Step 5 is the only step that interacts directly with the federation interfaces. 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 determines the junction key for the junction. 3. Using the junction key, the server does a local lookup to find the FSN of the target fileset. 4. Using the FSN, the server finds the NSDB node responsible for the target object. 5. 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. Expires June 12, 2008 [Page 11] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 5.3 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 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 AFS model of mounting the read-only volume at a path in the namespace different from that of the read-write volume. The federation protocol does not control or manage the relationship among filesets. It merely enables annotating the filesets with user-defined relationships. 6 Error Definitions ERR_OK Indicates the operation completed successfully. ERR_ACCESS Permission denied. The caller does not have the correct permission to perform the requested operation. Contrast this with ERR_PERM, which restricts itself to owner or privileged user permission failures. ERR_BADCHAR A UTF-8 string contains a character which is not supported in the context in which it being used. ERR_BADNAME A name string in a request consists of valid UTF-8 characters supported by the server but the name is not supported by the server as a valid name for current operation. ERR_BADTYPE An attempt was made to create an object of a type not supported by the server. Expires June 12, 2008 [Page 12] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 ERR_DENIED An attempt to lock a file is denied. Since this may be a temporary condition, the client is encouraged to retry the lock request until the lock is accepted. ERR_EXIST Object exists. The object specified already exists. ERR_INVALID Invalid argument or unsupported argument for an operation. ERR_IO I/O error. A hard error (for example, a disk error) occurred while processing the requested operation. ERR_NAMETOOLONG The filename in an operation was too long. ERR_NOENT No such object. The object being accessed does not exist. ERR_NOTDIR Not a directory. The caller specified a non- directory in a directory operation. ERR_NOTEMPTY An attempt was made to remove an object that was not empty. An FSN which has FSLs still defined for it. ERR_NOTSUPP Operation is not supported. ERR_PERM Not owner. The operation was not allowed because the caller is either not a privileged user (root) or not the owner of the target of the operation. ERR_WRONGSEC The security mechanism being used by the client for the operation does not match the server's security policy. The client should change the security mechanism being used and retry the operation. ERR_WRONGNSDB The NSDB location is not the one to be used for this operation 7 Protocol 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. Expires June 12, 2008 [Page 13] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 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 find other information about the information stored within that NSDB location) and the responses returned by the NSDB location. The primary use of this sub-protocol is by a fileset server in order to perform resolution, but it may also be used by an administrator to query the state of the system. The third of these sub-protocols defines the queries or other requests that are sent to a fileset server in order to get information from it or to modify the state of the fileset server in a manner related to the federation protocols. The primary purpose of this for an administrator to create or delete a junction or fileset or discover related information about a particular fileset server. The first and second sub-protocols are defined as LDAP operations, using the schema defined in appendices A and B. 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 NSDB service, and therefore we define in these sections the minimum level of LDAP functionality required to implement an NSDB location. The third sub-protocol is defined as ONC/RPC operations. The reason for using a different RPC mechanism (instead of mapping these operations onto LDAP) is to minimize the changes required to the fileset server. The three sub-protocols are defined in the next three sub-sections. 7.1 ADMINISTRATIVE NSDB OPERATIONS 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 fileserver. We require that each NSDB location can act as an LDAP server and that the protocol used for communicating between the admin entity and each NSDB 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. One important exception to this Expires June 12, 2008 [Page 14] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 rule is that the names of the error codes follow the convention (used widely in other protocols, including NFS) of having names that are entirely uppercase. 7.1.1 FSN_CREATE Description The administrator uses this operation to create a new FSN by requesting the NSDB to create a new FsnObject in its LDAP database with an FsnUuid of FSNUUID and an NsdbName of NSDBNAME. The NSDB location that receives the request SHOULD check that the NSDBNAME matches its own value and return an ERR_WRONGNSDB error if 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). Errors ERR_OK ERR_EXIST ERR_NOMEM ERR_INVALID ERR_PERM ERR_WRONGNSDB LDAP Request The admin chooses the FsnUuid (also known as the junction key) and NsdbName of the FSN. The FsnUuid should be chosen via a standard process for creating a globally unique UUID (described in RFC 4122). 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 Expires June 12, 2008 [Page 15] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 by the LDIF below, to the NSDB location NSDBNAME. This will create a new FsnObject on that NSDB location with the given attributes in the LDAP database. dn: fsnUuid=FSNUUID,nsdbName=NSDBNAME,ou=fed-fs changeType: add objectClass: FsnObject fsnUuid: FSNUUID nsdbName: NSDBNAME The definition of the FsnObject class is given in Appendix B. Each FsnObject is uniquely defined by its distinguished name (DN) which is a combination of the FSN's UUID, NSDB location, and the LDAP database organizational units. 7.1.2 FSN_DELETE Description Deletes a Fileset with the given FSN. This assumes that all the FSLs related to that FSN have already been deleted. If FSL records for this FSN still exist in the database of the NSDB that receives this request, then this function MUST return with an ERR_NOTEMPTY error. 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 ERR_NOTFOUND. Errors ERR_OK ERR_NOTFOUND ERR_INVALID ERR_NOTEMPTY ERR_PERM Expires June 12, 2008 [Page 16] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 LDAP Request The admin then sends an LDAP DELETE request to the NSDB server to remove the FsnObject from the NSDB server. An example LDIF for the delete request is shown below. dn: fsnUuid=FSNUUID,nsdbName=NSDBNAME,ou=fed-fs changeType: delete We assume that there is a trivial mapping between an FSN and the LDAP DN of the FsnObject for the LDAP records that represent information about that FSN. If this is not true, then operations that require mapping an FSN to the DN of an FsnObject may need to perform an LDAP query in order to discover the DN. This process is described below. In case an FSN is to be deleted, e.g., using the "fsn_delete FSNUUID NSDBNAME" command, the admin server sends an LDAP Search command to the NSDB server to first verify if the object exists by using the following filter: Query: Base: dc=company,dc=com Filter "(&(objectClass=FsnObject)(fsnUuid=FSNUUID)" The above filter searches for all FsnObject entries in the NSDB location's LDAP database that have the fsnUuid set to FSNUUID. If the FsnObject is found the NSDB will return the corresponding FsnObject entry to the admin. An example entry returned is shown below. LDAP Response: Count: 1 (No of Entries) Entries: dn: fsnUuid=FSNUUID,nsdbName=NSDBNAME,ou=fed-fs objectClass: FsnObject fsnUuid: FSNUUID nsdbName: NSDBNAME 7.1.3 FSN_MOUNT Description The fsn_mount operation logically mounts a target FSN (target_fsn) at the given pathname (relative to the root) of the parent FSN (parent_fsn). If a ROOT FSN has Expires June 12, 2008 [Page 17] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 been defined, then the ROOT fileset's FSN may be used. The pathname may start from / to represent the path from the root of the common federation namespace. If the pathname does not start with / then it treated as a relative path starting from the root of the parent FSN's location in the namespace. The fsn_mount operation is purely a namespace operation. The fsn_mount operation creates the parent and target FSN relationship that is used later by junction_create operation between the admin and the fileserver. The parent_fsn's NSDB maintains the relationship information created on an fsn_mount. Errors ERR_OK ERR_NOTFOUND ERR_INVALID ERR_NAMETOOLONG ERR_PERM LDAP Request On fileset mount operation the admin will generate an LDAP ADD request to the NSDB server using the example LDIF below. This creates a new FsnJunctionObject that establishes the mount relationship between the parent and target FSNs. dn: mountPath=PATH,parentFsnUuid=PARENTFSNUUID,ou=fed-fs changeType: add objectClass: FsnJunctionObject parentFsnUuid: PARENTFSNUUID targetFsnUuid: TARGETFSNUUID targetNsdbName: TARGETNSDBNAME mountPath: PATH The definition of the FsnJunctionObject class is given in Appendix B. Each FsnJunctionObject is uniquely defined by its distinguished name (dn) which is a combination of the parentFsnUuid and the mountPath (path either relative or absolute) where the target FSN is. 7.1.4 FSN_UNMOUNT Description Detaches the targetFsn from the parentFsn at the given pathname. The pathname can be relative to the root of the parentFsn or from the root of the federation Expires June 12, 2008 [Page 18] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 namespace. The parentFsn's NSDB location handles the unmount and removes the relationship between the ParentFsn and the TargetFsn. Errors ERR_OK ERR_NOTFOUND ERR_INVALID ERR_PERM LDAP Request In case a target_FSN is to be unmmounted, the associated FSNJunctionObject is deleted from the NSDB maintaining the parent fileset. An example delete request is shown below. LDAP Delete Request: dn: pountPath=PATH,parentFsnUuid=PARENTFSNUUID,ou=fed-fs changeType: delete 7.1.5 FSL_CREATE Description Creates a new Fileset location at the given location denoted by HOST:PATH for the given FSN. An fsl_uuid may be provided as an optional UUID for the FSL. 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. If the FSL belongs to an FSN that has another FSN mounted under it then there would be a related junction_create operation. Errors ERR_OK ERR_EXIST ERR_NOTFOUND ERR_INVALID ERR_PERM LDAP Request The FSL create command will result in the admin server sending an LDAP ADD request to create a new FslObject at the NSDB maintaining the given FSN. The example LDIF is shown below. The FSL object definition is provided in Appendix B. The HOST must be a fully qualified DNS name, and the PATH is the pathname where the fileset is located on that host. dn:fsl=HOST:PATH,fsnUuid=FSNUUID,nsdbName=NSDBNAME,ou=fed-fs changeType: add Expires June 12, 2008 [Page 19] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 objectClass: FslObject fsnUuid: FSNUUID nsdbName: NSDBNAME fsl: HOST:PATH type: nfs4 version: VERSION 7.1.6 FSL_DELETE Description Deletes the given Fileset location. The admin requests the NSDB location storing the FslObject to delete it from its database. This operation does not result in the fileset location's data being deleted at the fileserver. Errors ERR_OK ERR_NOTFOUND ERR_INVALID ERR_PERM LDAP Request dn: fsl=HOST:PATH,fsnUuid=FSNUUID,nsdbName=NSDBNAME,ou=fed-fs changeType: delete 7.1.7 FSL_UPDATE Description Update the attributes of a given FSL. This command results in a change in the attributes of the FslObject at the NSDB server maintaining this FSL. The attributes that must not change are the FSL UUID (if assigned) and the FSN UUID of the fileset this FSL implements. Errors ERR_OK ERR_NOTFOUND Expires June 12, 2008 [Page 20] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 ERR_INVALID ERR_PERM LDAP Request dn: fsl=HOST:PATH,fsnUuid=FSNUUID,nsdbName=NSDBNAME,ou=fed-fs changeType: modify replace: ATTRIBUTE-TYPE 7.1.8 FSL_STAT Description Find all attributes of a given FSL from the FSLObject stored at the NSDB location. Errors ERR_OK ERR_NOTFOUND ERR_INVALID ERR_PERM 7.2 FILESERVER to NSDB OPERATIONS 7.2.1 FSN_GET_FSL Description Return the list of FSLs for the given FSN (fsn_foo) matching the filter. The fileserver will convert the list of FSLs to the NFSv4 fs_locations. The filter specify the type of protocol (v4, v3), or type of data access (ro, rw). Errors ERR_OK ERR_NOTFOUND Expires June 12, 2008 [Page 21] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 ERR_INVALID ERR_PERM LDAP Request Query: ((&objectClass=FslObject)(fsnUuid=FSNUUID)) Response: count: N entries: dn: fsl=HOST:PATH,fsnUuid=FSNUUID,nsdbName=NSDBNAME,ou=fed-fs fslHost: HOST fslPath: PATH type: NFSv4 The server can scan through the results and find results whose type corresponds to the type of the client on whose behalf the server is performing the request, extracting the fslHost and fslPath (and possibly additional attributes) and using them to create a list of fs_locations that the client can use. 7.3 ADMIN to FILESERVER OPERATIONS Because the fileserver is not required to act as an LDAP server, the protocol for the admin to communicate with the fileserver is not required to be LDAP. We define these message exchanges using XDR to describe SUNRPC calls by the admin and responses from the fileset server. 7.3.1 Basic Definitions We begin by defining basic constants and structs, in XDR notation, that will be used to specify the types of the RPCs described in the rest of this subsection. #define FEDFS_MAX_UUID_LEN 64 #define FEDFS_MAX_NSDBNAME_LEN 256 #define FEDFS_MAX_HOSTNAME_LEN 128 #define FEDFS_MAX_PATHNAME_LEN 1024 Expires June 12, 2008 [Page 22] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 typedef opaque FedFsFsnUuid; typedef opaque FedFsHostName; typedef opaque FedFsNsdbName; typedef opaque FedFsPathName; struct FedFsFsn { FedFsFsnUuid junctionKey; FedFsNsdbName nsdb; }; struct FedFsFsl { FedFsHostName host; FedFsPathName path; }; struct FedFsJunctionTarget { FedFsFsnUuid uuid; FedFsNsdbName nsdb; FedFsPathName path; }; union FedFsFslsRes switch (bool status) { case ERR_OK : FedFsFsl fsls<>; default : void; }; union FedFsFsnsRes switch (bool status) { case ERR_OK : FedFsFsn fsns<>; default : void; Expires June 12, 2008 [Page 23] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 }; program FEDFS_PROG { version FEDFS_VERSION { void FEDFS_NULL(void) = 0; FedFsFslsRes FEDFS_HOST_FSLS(FedFsHostName host) = 1; FedFsFsnsRes FEDFS_HOST_FSNS(FedFsHostName host) = 2; FedFsFslsRes FEDFS_HOSTPATH_FSLS(FedFsHostName host, FedFsPathName path) = 3; FedFsCreateJunctionRes FEDFS_CREATE_JUNCTION(FedFsFsn fsn, FedFsPathName path) = 4; FedFsCreateExportRes FEDFS_CREATE_EXPORT(FedFsPathName path, FedFsPathName exportPath) = 5; } = 1; } = 100205; 7.3.2 FEDFS_HOST_FSLS, FEDFS_HOST_FSNS, FEDFS_HOSTPATH_FSLS Function These functions return lists of FSLs or FSNs that are served by the host. For FEDFS_HOSTPATH_FSLS, only the FSLs associated with a specific path are returned. Return the list of matching FSLs or FSNs for a given host/path at a fileserver. If successful, the status is ERR_OK and the value of the fsls or fsns is a list of matching FSNs or FSLs. If unsuccessful, the status code indicates the cause of the failure. Description Find all FSL or FSNs for a given host or find the FSL given a host:path pair. Errors ERR_OK ERR_NOTFOUND ERR_INVALID ERR_NAMETOOLONG ERR_PERM 7.3.3 FEDFS_CREATE_JUNCTION Description Create a junction from the given path on the server to the given fsn. Note that how the fileserver represents or maintains the junction is not defined by the fed-fs protocol. Expires June 12, 2008 [Page 24] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 Errors ERR_OK ERR_NOTFOUND ERR_INVALID ERR_PERM 7.3.4 FEDFS_CREATE_EXPORT Description Export the fileset rooted at the given path as an FSL at the given export path. Errors ERR_OK ERR_NOTFOUND ERR_INVALID ERR_PERM 8 Security Considerations To be added. 9 IANA Considerations None 10 Conclusions The federated filesystem protocol manages multiple independently administered fileservers to share namespace and referral information to enable clients to traverse seamlessly across them. 11 Glossary Administrator: user with the necessary authority to initiate administrative tasks on one or more servers. Expires June 12, 2008 [Page 25] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 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. 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. Junction key: The key to lookup a junction within an NSDB node or a local table of information about junctions. 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 Expires June 12, 2008 [Page 26] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 (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. 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. Expires June 12, 2008 [Page 27] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 Appendix B. Namespace Schema Class Objects objectclass ( 1.3.6.1.4.1.4203.666.121.5 NAME 'FsnObject' DESC 'Representing a Fed-fs Fileset' STRUCTURAL SUP Base MUST ( fsnUuid $ nsdbName $ type ) MAY ( descr $ annotation ) ) objectclass ( 1.3.6.1.4.1.4203.666.121.7 NAME 'FslObject' DESC 'Represents a physical instance of a fileset' STRUCTURAL SUP Base MUST ( fsl $ fsnUuid $ nsdbName $ fslHost $ fslPath $ type $ state $ fsType ) MAY ( version $ exportOptions $ descr $ annotation ) ) objectclass ( 1.3.6.1.4.1.4203.666.121.9 NAME 'FSNJunctionObject' DESC 'Represents a mount point' STRUCTURAL SUP Base MUST ( parentFsnUuid $ targetFsnUuid $ Expires June 12, 2008 [Page 28] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 nsdbName $ mountPath ) MAY ( descr $ annotation ) ) Expires June 12, 2008 [Page 29] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 12 References 12.1 Normative References [draft-fed-fs-req] Ellard, D., et al., Requirements for Federated File Systems, Internet Draft, June 2007. [RFC1094] Nowicki, B., "NFS: Network File System Protocol specification", RFC 1094, March 1989. [RFC1813] Callaghan, B., Pawlowski, B., and P. Staubach, "NFS Version 3 Protocol Specification", RFC 1813, June 12995. [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. [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. [RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC Text on Security Considerations", BCP 72, RFC 3552, July 2003. [RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally Unique IDentifier (UUID) URN Namespace", RFC 4122, July 2005. [RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.1", RFC 4346, April 2006. [RFC4511] Sermersheim, J., "Lightweight Directory Access Protocol (LDAP): The Protocol", RFC 4511, June 2006. [RFC4513] Harrison, R., "Lightweight Directory Access Protocol (LDAP): Authentication Methods and Security Mechanisms", RFC 4513, June 2006. Expires June 12, 2008 [Page 30] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 Author's Addresses 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 Daniel Ellard Network Appliance, Inc. 1601 Trapelo Rd, Suite 16 Waltham, MA 02451 US Phone: +1 781-768-5421 Email: ellard@netapp.com Craig Everhart Network Appliance, Inc. 7301 Kit Creek Rd Research Triangle Park, NC 27709 US Phone: +1 919-476-5320 Email: everhart@netapp.com Expires June 12, 2008 [Page 31] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Expires June 12, 2008 [Page 32] Internet-Draft draft-tewari-nfsv4-federated-fs-protocol-00 December 2007 Expires June 12, 2008 [Page 33]