A client is a computer or process that requests services on the network. A server is a computer or process that responds to a request for service from a client. A user accesses a service, which allows the use of data or other resources.

Figure 1 illustrates the client-server relationship. The upper right portion of the figure shows the z/OS NFS server. The lower right portion of the figure shows the z/OS NFS client. The left portion of the figure shows various NFS clients and servers which can interact with the z/OS NFS server and client. The center of the figure shows the Transmission Control Protocol/Internet Protocol (TCP/IP) network used to communicate between the clients and servers.

Figure 1. NFS client-server relationship

With the z/OS NFS server, you can remotely access MVS z/OS® conventional data sets or z/OS UNIX files from workstations, personal computers, and other systems that run client software for the Sun NFS version 2, version 3, and version 4 protocols, and the WebNFS protocols over TCP/IP network.

The z/OS NFS server acts as an intermediary to read, write, create or delete z/OS UNIX files and multiple virtual storage (MVS™) data sets that are maintained on a z/OS host system. The remote MVS data sets or z/OS UNIX files are mounted from the host processor to appear as local directories and files on the client system. This server makes the strengths of an z/OS host processor (storage management, high-performance disk storage, security, and centralized data) available to the client platforms.

With the z/OS NFS client, you can allow basic sequential access method (BSAM), queued sequential access method (QSAM), virtual storage access method (VSAM), and z/OS UNIX users and applications transparent access to data on systems that support the Sun NFS version 2 protocols, the Sun NFS version 3 protocols, and the Sun NFS version 4 protocols. The remote NFS Server can be a z/OS, UNIX, AIX®, or other system. The z/OS NFS client is implemented on z/OS UNIX and implements the client portion of the Sun NFS version 2 protocols, the Sun NFS version 3 protocols, and the Sun NFS version 4 protocols.

The NFS uses the communication services provided by TCP/IP, a suite of protocols that includes the remote procedure call (RPC) and External Data Representation (XDR) protocols. RPC allows a program on one machine to start a procedure on another machine, as if the procedure is local. XDR resolves the differences in data representation of different machines.

The NFS, then, can be used for file sharing between platforms and file serving (as a data repository).

If you use NFS as a file server, the z/OS UNIX file system might be a better choice than using z/OS conventional MVS data sets, because of its UNIX-based features.