Please Whitelist This Site?

I know everyone hates ads. But please understand that I am providing premium content for free that takes hundreds of hours of time to research and write. I don't want to go to a pay-only model like some sites, but when more and more people block ads, I end up working for free. And I have a family to support, just like you. :)

If you like The TCP/IP Guide, please consider the download version. It's priced very economically and you can read all of it in a convenient format without ads.

If you want to use this site for free, I'd be grateful if you could add the site to the whitelist for Adblock. To do so, just open the Adblock menu and select "Disable on tcpipguide.com". Or go to the Tools menu and select "Adblock Plus Preferences...". Then click "Add Filter..." at the bottom, and add this string: "@@||tcpipguide.com^$document". Then just click OK.

Thanks for your understanding!

Sincerely, Charles Kozierok
Author and Publisher, The TCP/IP Guide


NOTE: Using software to mass-download the site degrades the server and is prohibited.
If you want to read The TCP/IP Guide offline, please consider licensing it. Thank you.

The Book is Here... and Now On Sale!

Get The TCP/IP Guide for your own computer.
The TCP/IP Guide

Custom Search







Table Of Contents  The TCP/IP Guide
 9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)
      9  Network File and Resource Sharing Protocols and the TCP/IP Network File System (NFS)
           9  TCP/IP Network File System (NFS)

Previous Topic/Section
TCP/IP Network File System (NFS)
Previous Page
Pages in Current Topic/Section
1
2
3
Next Page
NFS Architecture and Components
Next Topic/Section

NFS Overview, History, Versions and Standards
(Page 2 of 3)

Overview of NFS Architecture and General Operation

NFS follows the classical TCP/IP client/server model of operation. A hard disk or a directory on a storage device of a particular computer can be set up by an administrator as a shared resource. This resource can then be accessed by client computers, which mount the shared drive or directory, causing it to appear like a local directory on the client machine. Some computers may act as only servers or only clients, while others may be both: sharing some of their own resources and accessing resources provided by others.

NFS uses an architecture that includes three main components that define its operation. The External Data Representation (XDR) standard defines how data is represented in exchanges between clients and servers. The Remote Procedure Call (RPC) protocol is used as a method of calling procedures on remote machines. Then, a set of NFS procedures and operations works using RPC to carry out various requests. The separate Mount protocol is used to mount resources as mentioned above.

One of the most important design goals of NFS was performance. Obviously, even if you set up a file on a distant machine as if it were local, the actual read and write operations have to travel across a network. Usually this takes more time than simply sending data within a computer, so the protocol itself needed to be as “lean and mean” as possible. This decision led to some interesting decisions, such as the use of the unreliable User Datagram Protocol (UDP) for transport in TCP/IP, instead of the reliable TCP like most file transfer protocols do. This in turn has interesting implications on how the protocol works as a whole.

Another key design goal for NFS was simplicity (which of course is related to performance). NFS servers are said to be stateless, which means that the protocol is designed so that servers do not need to keep track of which files have been opened by which clients. This allows requests to be made independently of each other, and allows a server to gracefully deal with events such as crashes without the need for complex recovery procedures. The protocol is also designed so that if requests are lost or duplicated, file corruption will not occur.

Key Concept: The Network File System (NFS) was created to allow client hosts to access files on remote servers as if they were local. It was designed primarily with the goals of performance, simplicity and cross-vendor compatibility.



Previous Topic/Section
TCP/IP Network File System (NFS)
Previous Page
Pages in Current Topic/Section
1
2
3
Next Page
NFS Architecture and Components
Next Topic/Section

If you find The TCP/IP Guide useful, please consider making a small Paypal donation to help the site, using one of the buttons below. You can also donate a custom amount using the far right button (not less than $1 please, or PayPal gets most/all of your money!) In lieu of a larger donation, you may wish to consider purchasing a download license of The TCP/IP Guide. Thanks for your support!
Donate $2
Donate $5
Donate $10
Donate $20
Donate $30
Donate: $



Home - Table Of Contents - Contact Us

The TCP/IP Guide (http://www.TCPIPGuide.com)
Version 3.0 - Version Date: September 20, 2005

© Copyright 2001-2005 Charles M. Kozierok. All Rights Reserved.
Not responsible for any loss resulting from the use of this site.