Chapter 11. Network File
NFS provides its services through a client-server
relationship. The computers that make their file systems,
directories, and other resources available for remote access are called
servers. The act of making file systems available is called exporting.
The computers, or the processes they run, that use a server's resources are
considered clients. Once a client mounts a file system that a server exports,
the client can access the individual server files (access to exported
directories can be restricted to specific clients).
The following are a list of terms that are used throughout this discussion:
- A computer that makes its file systems, directories,
and other resources available for remote access.
- The computers, or processes that use a server's
- The act of making file systems available to remote
- The act of a client accessing the file systems a
The major services provided by NFS are:
- From the /usr/sbin/rpc.mountd daemon on the server
and the /usr/sbin/mount command on the client. The mountd daemon is a
Remote Procedure Call (RPC) that answers a client request to mount a file
system. The mountd daemon finds out which file systems are available by reading
the /etc/xtab file. In addition, the mountd daemon provides a list of currently
mounted file systems and the clients on which they are mounted.
Remote File Access
- From the /usr/sbin/nfsd daemon on the server and the
/usr/sbin/biod daemon on the client. Handles client requests for files. The
biod daemon runs on all NFS client systems. When a user on a client wants to
read or write to a file on a server, the biod daemon sends this request to the
- From the /usr/sbin/rpc.rexd daemon on the server and
the /usr/bin/on command on the client.The rexd daemon executes
programs for remote machines when a client issues a request to execute a
program on a remote machine.
Remote System Statistics
- From the /usr/sbin/rpc.rstatd daemon on the server
and the /usr/bin/rup command on the client. The rstatd daemon is a
server that returns performance statistics obtained from the kernel.
Remote User Listing
- From the /usr/lib/netsvc/rusers/rpc.rusersd daemon on
the server and the /usr/bin/rusers command on the client. The rusersd
daemon is a server that responds to queries from the rusers command by
returning a list of users currently on the network.
- Provides boot parameters to SunOS diskless clients
from the /usr/sbin/rpc.bootparamd daemon on the server.
- From the /usr/lib/netsvc/rwall/rpc.rwalld daemon on
the server and the /usr/sbin/rwall command on the client. The rwalld
daemon handles requests from the rwall command. The rwall
command sends messages to all users on the network.
- Sends a one-way stream of Remote
Procedure Call (RPC) packets from the
/usr/lib/netsvc/spray/rpc.sprayd daemon on the server and the
/usr/sbin/spray command on the client.
- Provides a user authentication service for PC-NFS
from the /usr/sbin/rpc.pcnfsd daemon on the server.
An NFS server is stateless. That is, an NFS
server does not have to remember any transaction information about its clients.
In other words, NFS transactions are atomic: A single NFS
transaction corresponds to a single, complete file
operation. NFS requires the client to remember any information needed for later
Figure 101 is an illustration of the NFS configuration
discussed in this section.
Figure 101: A Typical NFS Environment
The environment illustrated in Figure 101 includes two
NFS servers and three clients where one system is both a server and a client.
The CRoom server exports its directories allowing all other systems to have
access to them. The Accounts server shares one directory that only Marketing
has access to. The following section recreates the scenario illustrated and
discusses any challenges and tasks that arise while administrating NFS in this
Installation, and Configuration of NFS