Technical data

NFS Server
20.1 Key Concepts
to select the correct file system for the application, and to ensure that your file
systems are adequately protected while granting access to users on remote hosts.
The following sections serve as a review only. If you are not familiar with NFS,
see the DIGITAL TCP/IP Services for OpenVMS Concepts and Planning manual
for more information.
20.1.1 Clients and Servers
NFS is a client/server environment that allows computers to share disk space
and allows users to work with their files from multiple computers without
copying them to their local system. The NFS server can make any of its file
systems available to the network by exporting the files and directories. Users
on authorized client hosts access the files by mounting the exported files and
directories. The NFS client systems accessing your server may be running UNIX,
OpenVMS, or other operating systems.
The NFS client identifies each file system by the name of its mount point on
the server. The mount point is the name of the device or directory at the top of
the file system hierarchy that you create on the server. An NFS device is always
named DNFSn. The NFS client makes file operation requests by contacting your
NFS server. The server then performs the requested operation.
20.1.2 NFS File Systems on OpenVMS
The OpenVMS system includes a hierarchy of devices, directories and files stored
on a Files–11 On-Disk Structure (ODS-2) formatted disk. OpenVMS and ODS-2
define a set of rules that govern files within the OpenVMS file system. These
rules define the way that files are named and catalogued within directories.
If you are not familiar with OpenVMS file systems, refer to the OpenVMS System
Manager’s Manual: Essentials to learn how to set up and initialize a Files–11
disk.
You can set up and export two different kinds of file systems: a traditional
OpenVMS file system or a UNIX style file system built on top of an OpenVMS file
system. This UNIX style file system is called a container file system.
Each file system is a multilevel directory hierarchy: on OpenVMS systems, the
top level of the directory structure is the master file directory (MFD). The MFD
is always named [000000] and contains all the top-level directories and reserved
system files. On UNIX systems or with a container file system, the top-level
directory is called the root.
20.1.2.1 Selecting a File System
You can set up and export either an OpenVMS file system or a container file
system. Which one you choose depends on your environment and the user needs
on the NFS client host.
You might use an OpenVMS file system if:
• Your environment calls for extensive file sharing between your OpenVMS
system and another OpenVMS host, or between your system and a UNIX
client.
• Users on the client need to maintain multiple versions of files.
Select the OpenVMS file system if you need to share files between users on
OpenVMS and users on NFS clients.
20–2 NFS Server