Overview of NFS Services

Network File System (NFS) provides transparent access to files from anywhere on the network. An NFS server makes a directory available to other hosts on the network by “exporting” the directory. An NFS client provides access to the NFS server’s directory by “mounting” the directory. To users on the NFS client, the directory looks like part of the local file system. For information on configuring and administering NFS, see Chapter 2 “Configuring and Administering NFS Services”.

Network Information Service (NIS) allows centralized management of common configuration files, like /etc/passwd, /etc/hosts, and /etc/services. An NIS “master server” holds master copies of the configuration files, or “maps”. The master server may distribute copies of the maps to NIS “slaves servers” to provide load balancing and reliability. An NIS client gets configuration information from the master server or a slave server instead of from its local configuration files. (Some local configuration files, like /etc/passwd and /etc/group, can be used in addition to the NIS maps.) For more information, see Chapter 4 “Configuring and Administering NIS”.

Network Information Service Plus (NIS+) is the next generation of NIS. Like NIS, it provides centralized management of common configuration files. Unlike NIS, it allows you to create multiple domains in a hierarchical structure called a “namespace.” It also has enhanced security features. It allows you to update the NIS+ databases from any client host in the network without having to log into the master server. For more information, see Chapter 5 “Configuring and Administering NIS+”.

Network Lock Manager and Network Status Monitor (rpc.lockd and rpc.statd) provide file locking and synchronized file access to files that are shared with NFS. Files may be locked with lockf or fcntl. For more information, see the following man pages: lockd(1M), statd(1M), lockf(2), and fcntl(2).

Remote Procedure Call (RPC) is the mechanism that allows NFS clients and NFS servers to communicate. You can write your own RPC applications, using rpcgen, an RPC compiler that simplifies RPC programming. On HP-UX 10.30 and later, Transport-Independent RPC (TI-RPC) is supported. For information on RPC and rpcgen, see Power Programming with RPC, by John Bloomer, published by O’Reilly and Associates, Inc.

Remote Execution Facility (REX) allows you to execute commands interactively on a remote host while your local environment is simulated on the remote host. To use REX, you issue the on command on your local host, supplying the command you want to execute remotely and the name of the remote host where you want the command to execute. Your current environment variables are then copied to the remote host, and your home directory is mounted on the remote host using NFS. For information on configuring, administering, and using REX, see Chapter 7 “Configuring and Using the Remote Execution Facility (REX)”

The rup command collects and displays status information about the hosts on the local network. All hosts running the rstatd daemon will respond to queries from the rup command. For more information, see the man pages rstatd(1M) and rup(1). For information on configuring rstatd, see “Configuring the Other NFS Daemons and Services”.

The rusers command collects and displays information about all users logged into the hosts on the local network. All hosts running the rusersd daemon will respond to queries from the rusers command. For more information, see the man pages rusersd(1M) and rusers(1). For information on configuring rusersd, see “Configuring the Other NFS Daemons and Services”.

The rwall program allows you to broadcast a message to all the users logged into a remote host. The rwall program sends a message to a specified host where the rwalld daemon is running. The rwalld daemon then writes the message to all the users logged into that host. For more information, see the man pages rwalld(1M) and rwall(1M). For information on configuring rwalld, see “Configuring the Other NFS Daemons and Services”.

The spray command sends a stream of packets to a specified host and then reports how many of the packets were received and what the transfer rate was. All hosts running the sprayd daemon will respond to packets sent by the spray command. For more information, see the man pages sprayd(1M) and spray(1M). For information on configuring sprayd, see “Configuring the Other NFS Daemons and Services”.

The quota command, which displays information about a user’s disk usage and limits, may be used to get information about a user on a remote host, if the rquotad daemon is running on the remote host. For more information, see the man pages rquotad(1M) and quota(1). For information on configuring rquotad, see “Configuring the Other NFS Daemons and Services”.