FedFsGlossary
From Linux NFS
Project: fedfs-utils
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Introduction
This article contains a glossary of terms related to FedFS.
Glossary
Partially derived from draft-ietf-nfsv4-federated-fs-protocol-13.
Administrative Client
A network host that performs domain administrative tasks remotely using the NSDB and ADMIN protocols.
Administrator
A user with the necessary authority to initiate administrative tasks on one or more servers in a FedFS domain.
Domain Root Directory
A domain root directory is the top-level directory of a FedFS domain.
Federation
A collection of independently administered fileservers that are linked together by a common namespace. Also known as a FedFS Domain.
FedFS
FedFS is short for Federated File System. It's a set of administrative protocols and techniques for creating a file name space that can cross multiple shares on multiple file servers, and is consistent no matter which client it is accessed from.
FedFS Domain
A FedFS domain is a file name space that can cross multiple shares on multiple file servers. A FedFS domain is typically a single administrative entity, and has a name that is similar to a DNS domain name.
File-access client
A file-access client accessed data stored on fileservers via a standard file-access protocol such as SMB or NFS.
File-access protocol
A network filesystem access protocol such as NFSv4 or CIFS.
Fileserver
A fileserver provides access to file storage via a standard file-access protocol such as NFS or SMB.
Fileset
A fileset is a collection of files and directories that are considered as a single administrative unit in a FedFS domain. Each fileset may reside at a single location, or it may be replicated to several locations. All files within a fileset are descendants of one directory. Filesets do not span filesystems.
Globally Useful Name
A Globally Useful Name is a pathname in the FedFS domain namespace which is the same no matter which client is used to access the file.
Junction
A junction is a link between two shared file systems. The two shared file systems may not reside on the same server. Junctions tie together separate shared file systems into a single FedFS domain namespace.
A junction's pathname is the path in a file server's local namespace where the junction resides. A junction's target is a list of locations.
A location is a pair consisting of a file server host and the export path of a file system on that host. Each location is a replica of the same file system data. A target may contain one or more location.
Currently there are two types of junctions:
- An NFS basic junction stores location information directly in each junction
- A FedFS junction stores location information on an LDAP server so it can be shared
Junction Resolution
The process where a file server converts a junction's target to data that can be used to respond to a file-access client during a referral event.
Location
Each replica of the linked-to file system is called a fileset location, or location, for short. A location is represented as an export path paired with a server name or IP address.
Namespace
A filename/directory tree that a sufficiently authorized client can observe.
Namespace Database
A Namespace Database, also known as an NSDB, is the central repository of FedFS domain namespace information that is shared among all file servers in a FedFS domain. It is accessed via the LDAP protocol.
Referral
A referral is a file server response that tells a file-access client to look elsewhere for the shared file system it wants. A referral event can occur, for example, when a file server reports to a client that the object the client is attempting to access has moved. The client responds by requesting a list of locations where it can find the object.
Replica
A replica is a copy of a fileset. Replicas are used to increase availability or performance. Updates to replicas appear to occur in the same order, but do not necessarily occur simultaneously.
