NFS Terminology

This section presents some of the basic terminology that must be understood to work with the NFS service. Expanded coverage of the NFS service is included in Chapter 16, Accessing Remote File Systems Reference.

NFS Servers and Clients

The terms client and server are used to describe the roles that a computer assumes when sharing file systems. If a file system resides on a computer's disk and that computer makes the file system available to other computers on the network, that computer acts as a server. The computers that are accessing that file system are said to be clients. The NFS service enables any computer to access any other computer's file systems, and at the same time, to provide access to its own file systems. A computer can assume the role of client, server, or both at any particular time on a network.

Clients access files on the server by mounting the server's shared file systems. When a client mounts a remote file system, it does not make a copy of the file system. Rather, the mounting process uses a series of remote procedure calls that enable the client to access the file system transparently on the server's disk. The mount resembles a local mount and users type commands as if the file systems were local. See "Mounting File Systems" for information about tasks that mount file systems.

After a file system has been shared on a server through an NFS operation, it can be accessed from a client. You can mount an NFS file system automatically with autofs. See "Automatic File-System Sharing" and "Autofs Administration Task Overview" for tasks that involve the share command and autofs.

NFS File Systems

The objects that can be shared with the NFS service include any whole or partial directory tree or a file hierarchy-including a single file. A computer cannot share a file hierarchy that overlaps a file hierarchy that is already shared. Peripheral devices such as modems and printers cannot be shared.

In most UNIX system environments, a file hierarchy that can be shared corresponds to a file system or to a portion of a file system. However, NFS support works across operating systems, and the concept of a file system might be meaningless in other, non-UNIX environments. Therefore, the term file system that is used throughout this guide refers to a file or file hierarchy that can be shared and mounted with NFS.