| Lesson 3 || Remote procedure calls |
| Objective || Explain the relationship between remote procedure calls and NFS. |
Remote Procedure Calls
Remote procedure calls (RPCs) enable NFS to transparently provide remote files to local computers. An RPC allows a client program to request a service from another computer without needing to know network details. Consequently, an RPC frees NFS from network-specific implementations and allows NFS to focus on providing network file access semantics.
File access semantics: When a file is opened, closed, read from, or written to, certain guidelines, or semantics must be in place. These semantics are "right-of-way" indicators, describing what happens when programs make conflicting requests.
For example, a read/write semantic would define who has the right-of-way when one program reads from a file that is being written to by another program.
The following SlideShow illustrates how RPC enables an NFS client to mount and access remote filesystems.
Remote Procedure Call Process
The NFS daemon (
rpc.nfsd) and RPC mounter (
rpc.mountd) do not need to run on the NFS client. Save some system memory and turn them off.
Listing registered RPC programs
When an RPC program such as
rpc.mountd starts, it must register itself with the portmapper program,
rpcinfo command, with the
-p parameter, lists all registered RPC programs.
For example, to list all registered programs on your local system, use
rpcinfo -p. To list all registered programs on a remote server, supply the hostname:
rpcinfo -p server.mycompany.com.
In the next lesson, you will learn how to configure a NFS server.
Nfs Rpc - Quiz
Before moving on to the next lesson, click the Quiz link below to answer some questions about NFS and RPC. Nfs Rpc - Quiz