449 lines
20 KiB
HTML
449 lines
20 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<HTML>
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<HEAD>
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<META NAME="GENERATOR" CONTENT="SGML-Tools 1.0.9">
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<TITLE>Network Install HOWTO: Quick Guide </TITLE>
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<LINK HREF="Network-Install-HOWTO-4.html" REL=next>
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<LINK HREF="Network-Install-HOWTO-2.html" REL=previous>
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<LINK HREF="Network-Install-HOWTO.html#toc3" REL=contents>
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</HEAD>
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<BODY>
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<A HREF="Network-Install-HOWTO-4.html">Next</A>
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<A HREF="Network-Install-HOWTO-2.html">Previous</A>
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<A HREF="Network-Install-HOWTO.html#toc3">Contents</A>
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<HR>
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<H2><A NAME="quickguide"></A> <A NAME="s3">3. Quick Guide </A></H2>
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<P>
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<!--
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network install!Quick Guide
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-->
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This chapter gives some overview information about installing Linux over a
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network. All examples and information here can be considered generic between
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different Linux distributions. If you want more specific information for a
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particular distribution then please read one of the following relevant chapters.
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<P>
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<P>
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<H2><A NAME="ss3.1">3.1 Advantages & Disadvantages</A>
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</H2>
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<P>The following is a list of advantages and disadvantages of installing Linux over
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a network and the automatic installation features available with many
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distributions of Linux. The list is in no specific order:
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<P>
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<P>
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<H3>Advantages</H3>
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<P>
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<UL>
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<LI>Fastest installation (on a good network)</LI>
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<LI>Automatic configuration available (unattended installation)</LI>
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<LI>Very quick installation of many systems</LI>
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<LI>No need for physical installation media</LI>
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<LI>Customisable installation with packages not available from the standard distribution</LI>
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<LI>Once the install system is setup and working installations are very simple</LI>
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<LI>Multiple system configurations available for automatic installation with different config files</LI>
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<LI>Simultaneous installation from a single source</LI>
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<LI>No need for an install media library, space-saving</LI>
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<LI>Very easy to update</LI>
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<LI>No problems with reading install media</LI>
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</UL>
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<P>
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<P>
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<H3>Disadvantages</H3>
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<P>
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<UL>
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<LI>Slow installation (on a bad network)</LI>
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<LI>Added complexity of installation</LI>
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<LI>Time needed initially to set up an install server</LI>
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<LI>Relies on network and connectivity</LI>
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<LI>Uses network bandwidth</LI>
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<LI>A server machine is required (expensive)</LI>
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</UL>
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<P>
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<P>
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<H2><A NAME="ss3.2">3.2 Automatic vs Manual Installation</A>
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</H2>
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<P>This section briefly compares the differences between automatic (or unattended)
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installations with the more common manual installations available. This should
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give you a good idea of which system is right for your usage.
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<P>
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<P>
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<H3>Automatic Installation</H3>
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<P>Automated or unattended installation is probably less used and less well known
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for installing systems than manual installation. This instantly gives rise to
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the challenges of trying to educate people about what it is and how to use it.
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Once you understand the basics of networked installation then automatic
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installation is a natural next step to take when installing and configuring
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your systems.
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<P>Automatic installation has the major drawback of a longer setup period required
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at the start of your process. This is to set up the install server (which you
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need to do for any network install environment) but you must also make up one or
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more configuration files for your install client to read. It is this setup
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time and slight added complexity that you must weigh up before deciding whether
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to do manual or automatic installations. Basically, as a rule of thumb, the
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more machines you have to install, the more time will be saved by using
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automatic installation techniques.
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<P>Automated installations are very easy to perform once you have the initial setup
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completed. You boot your client system in any way shape or form you like
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(usually by floppy disk) but you also provide access to your configuration file
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to the client at install time (usually either on the floppy disk or over the
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network connection). The configuration file contains all the required
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information that your client will need for installation, from what
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mouse/keyboard to use right through to the packages that you want installed on
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your system.
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<P>Another large bonus point of using the automated installation techniques is that
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most Linux distributions also provide means to add customised packages to the
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system at install time. This means that you can install packages that are not
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provided by the particular Linux distribution you are installing. There are
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normally also further configuration steps available such as the ability to write
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scripts for your installation that will get performed before, during, or after
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the install is complete. This all adds up to providing much faster installation
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of a complete system that is already setup in a customised way for your
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particular environment.
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<P>
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<P>
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<H3>Manual Installation</H3>
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<P>This is the method of Operating System (OS) installation that most people are used
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to. Commonly we install our base OS using CDROM disks and boot from CDROM or
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floppy disk before proceeding through a program of menus that allow us to
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customise certain options. This is probably the greatest benefit of Manual
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Installation i.e. most people are familiar with the process. However, it can
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bring other benefits too such as a quick/easy/simple installation and this
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method of installation is used more (therefore tested more) than other
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methods of installation so it might just be more reliable too.
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<P>The problems with manual installation come when you update your system very
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regularly, you are installing a large number of systems, or you want to have a
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particularly customised setup. Manual installation will not allow you to add
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extra programs to your OS at install time, you will have to install the OS then
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boot it before configuring the programs you want in the way that you would like.
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Also, this method can be quite time consuming if you are installing lots of
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systems, particularly if you only have a few sets of CDs.
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<P>Manual installation can still be done using a networked install environment.
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You can do this on any compatible OS that allows you to boot your client
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machine ready for installation before loading your network drivers and
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contacting your install server. All the data that would otherwise have been
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copied from CD images is now sent over the network instead.
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<P>
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<P>
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<H2><A NAME="ss3.3">3.3 Hardware</A>
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</H2>
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<P>You do not require any special hardware in order to install Linux over a network
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in either manual or automated mode. The basic requirements are:
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<OL>
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<LI>That you have a server machine available to you that has enough storage
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space on it to hold the install image that you want to transfer over the
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network.</LI>
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<LI>Ensure that this server is powerful enough to cope with the load that is
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going to be placed upon it.</LI>
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<LI>A network connection between your server and the client you want to
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install.</LI>
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<LI>A client machine with the appropriate hardware for the installation that
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you are intending to do.</LI>
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</OL>
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<P>Some examples where you might require specific hardware may be if you have a
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specialised network or if you need to attach more storage to your server, for
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example. In the example of attaching storage to your server, it does not matter
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in any way to the installation process where the install image is held, it can
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be on a local hard disk, in a RAID array, on a distributed filesystem or anywhere
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that the server machine can access reliably and quickly.
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<P>It goes without saying that if you don't have a network or your network is
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unreliable or slow then do not attempt network installations as they may fail
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or take a very long time to complete.
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<P>
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<P>
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<H2><A NAME="ss3.4">3.4 Software/Services</A>
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</H2>
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<P>You will require a basic understanding of some of the services that run on a
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Linux based machine in order to setup your install server. These are services
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that make your install image available over your local network to the client
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machines that you want to install. In addition you will also need basic Linux
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administration skills in order to set up and maintain your server well.
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<P>Most Linux distributions have a network installation method that makes use of
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between one and three methods of transferring data cross a network. These
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services may or may not have an impact on the installation you are going to
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perform at the client end. The differences between the services will depend on
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the Linux distribution you are installing and any distinctions that this
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distribution makes between these services.
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<P>The three data transfer services are NFS (Network Filesystem), HTTP (Hypertext
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Transfer Protocol) and FTP (File Transfer Protocol). Each of these services
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is slightly different in the way that it operates, the function that it is
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designed for, and the way that you administrate it. Basic guidance is provided
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throughout this HOWTO about what these differences are but you are recommended
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to familiarise yourself with each of them so that you can manage your system
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responsibly and make informed choices about the services that you run.
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<P>
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<P>
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<H2><A NAME="ss3.5">3.5 Generic Server Setup Guide</A>
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</H2>
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<P>This section gives a brief run down of setting up an install server for a
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'general' Linux distribution. The terms and theory here are as general to all
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Linux distributions as they can be and are designed specifically to give you a
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very quick overview of what network installations involve. If you want to
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perform network installations on your own machines then you are advised to read
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the relevant sections of this HOWTO in full. If the HOWTO does not contain a
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section for the distribution that you want to install then you can either change
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the distribution you are installing over the network to match the HOWTO or use
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the following as a very rough guide on how to do it.
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<P>
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<P>
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<H3>Begin Setup</H3>
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<P>This section explains how to set up your server machine to be an install server
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for a generic Linux distribution. For most distributions you can use any other
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distribution as the install server. For example, you can install Redhat over
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your network using a server installed with SuSE.
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<P>This guide starts from the point where you have a machine installed with Linux
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which is already up and running and connected to your network. If you require
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help with installing Linux on your server then please consult the Further
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Information section of this HOWTO in
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<A HREF="Network-Install-HOWTO-10.html#AppendixA">Appendix A</A>.
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<P>
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<P>
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<H3>Setting Up Filespace</H3>
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<P>
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<!--
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network install!generic
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-->
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In order to set up an install server you will need to put on all the required
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data that will be needed to perform a full installation of the Linux
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distribution you are going to serve. For example, if you are used to installing
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Linux using CDs then you will need space on your server to copy <EM>ALL</EM>
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the contents of each CD onto your server.
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<P>So, before you even think about setting up your machine as an install server,
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you must check that you have the required space available. This sounds like a
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trivial thing to check but it is very important and easily forgotten when you're
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setting up.
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<P>
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<P>
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<H3>How much space will you need?</H3>
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<P>A guide for the amount of space that you will require will be the amount of
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space on your install media that you are intending to copy from later. This
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might be one of the following approximate examples:
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<UL>
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<LI>Number of CDs x 650Mb</LI>
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<LI>Number of ISO images x 650Mb</LI>
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</UL>
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<P>
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<P>
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<H3>How much space do you have?</H3>
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<P>You will need the appropriate amount of space available to your system on some
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local filesystem. It does not matter what form this takes, whether it's a RAID
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device, local disk (either SCSI or IDE), etc. Ensure that the space you intend
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to use is formatted with your chosen filesystem and is mounted.
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<P>You can check this space with the command:
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<PRE>
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df -h
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</PRE>
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<P>If this output shows you have enough space to copy your install media then
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great, you can continue installation. If not then it's time to think about an
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upgrade to your intended server machine!
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<P>
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<P>
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<H3>Copy Installation Media</H3>
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<P>Once you know you have enough space available it's time to start copying your
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install media to your chosen filesystem and directory. This might involve
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copying the entire contents of all your CDs to one install directory on your
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server or copying the data over the network by some method, etc.
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<P>
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<P>
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<H3>Enable Remote Access</H3>
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<P>Time to make your install data available to other machines on the network.
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Most distributions allow installation over the network using NFS, HTTP and FTP
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protocols. You can select which of these will be used at install time on the
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client. If one of the services is not setup on the machine then it will still
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be available for selection by the client but the install will not work.
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Therefore, it is either best to enable all three services on your server (so
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they all work on each client machine) or if you don't enable all three then
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advertise the fact very well and say which service should be used for your
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particular install server.
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<P>
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<P>
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<H3>NFS</H3>
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<P>To install over NFS you need to meet certain conditions on the server:
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<UL>
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<LI>Your install directory is exported</LI>
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<LI>NFS is installed and running</LI>
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<LI>Portmap is running</LI>
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</UL>
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<P>To export your install directory edit the <CODE>/etc/exports</CODE> file and add an
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entry for your installation target directory to it. If you are not sure about
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exporting filesystems then see your man page for the exports file at
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exports (5).
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<P>
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<P>
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<H3>FTP</H3>
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<P>To install over FTP you need to allow FTP access to the directory that you have
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setup on the server as the installation directory. This can be either anonymous
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FTP access or access through a named account with a password. Anonymous access
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is probably best unless you have a reason to protect your install server via
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a password.
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<P>If you want anonymous FTP to point to a different directory then you can use
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sym links to point to the directory that you have set up as the install
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directory on the server. This will allow FTP into a chrooted environment but
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still give you access to the install images in a different location.
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<P>
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<P>
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<H3>HTTP</H3>
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<P>If you have a web server running and want to enable HTTP access to your install
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server then add sym links from your document root to the install server
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directory and this will grant access. If you are not familiar with web servers
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or are not comfortable with this approach then leave out HTTP access from your
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install server as it provides no benefits over NFS or FTP installs which may
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be simpler to set up.
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<P>If you do choose to use HTTP then basically all you have to do is make the
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install directory visible to your web server by making it appear under the
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document root by some means.
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<P>
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<P>
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<H3>Basic Setup Complete</H3>
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<P>You have now completed the basic setup of your install server. Different
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distributions will grant you different options for further customisation
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techniques of the installation process. The most commonly found customisation
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is the option to install packages that do not come as standard with the
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distribution you are installing. However, there may be further customisations
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you want to do on your particular server or that are available for your
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particular Linux distribution.
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<P>
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<P>
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<H2><A NAME="ss3.6">3.6 Generic Client Install Guide</A>
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</H2>
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<P>This section gives a brief run down of setting up a client machine using your
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install server. The terms and theory here are as general to all Linux
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distributions as I can be and are designed specifically to give you a very
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quick overview of what network installations involve. If you want to perform
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network installations on your own machines then you are advised to read the
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relevant sections of this HOWTO in full. If the HOWTO does not contain a
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section for the distribution that you want to install then you can either
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change the distribution you are installing over the network to match the HOWTO
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or use the following as a very rough guide on how to do it.
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<P>
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<P>
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<H3>Create Config Files</H3>
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<P>You only need to read/follow this section if you are intending to use an
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automated install process, if you intend to do a manual installation over
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your network then skip this section. Here we go through the process of creating
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configuration files that the installer will read in order to create the
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configuration of our client machines we are installing during an unattended
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network installation.
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<P>
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<P>
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<H3>Configuration Program Installation</H3>
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<P>In order to start creating your config files you will need to install the
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relevant config file editor. Each distribution that is capable of installing
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in unattended mode over the network will provide some means of editing config
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files. Make sure you have these installed on some Linux machine that will
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allow you to create and save all the different configurations you might want
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to install on your network.
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<P>
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<P>
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<H3><A NAME="genericbasicconfig"></A> Create A Basic Config File </H3>
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<P>Once you have confirmed that you have the configuration program package
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installed, you can start to create configuration files. For most situations
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the basic configuration described here will be sufficient to perform your
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installations.
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<P>Start the configuration program that you have on your system. In most cases,
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you will now be presented with a window that allows you to configure most of
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your installation options as if you were installing a new machine or performing
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an upgrade. You can proceed through each menu, configuring your options for a
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particular system or set of similar systems that you wish to automatically
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install.
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<P>Once you have progressed through each configuration screen, you are ready to
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save out your configuration file to disk. Click the save button and choose a
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location on your system to store configuration files. If you are creating lots
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of different configurations then it might be worthwhile creating your own
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configuration repository - don't forget to name the files sensibly so you know
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which is which.
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<P>
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<P>
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<H3>Advanced Config File Setup</H3>
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<P>Before attempting advanced configuration please make sure that you have first
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created a valid basic configuration file as described
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<A HREF="#genericbasicconfig">above</A>.
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It is perfectly possible to create your own configuration files from scratch
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but it is far easier to use the tools provided to do the job for you!
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<P>Once you have your configuration file saved, you can open it in your favourite
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text editor. You can use or modify any of the existing tags in your file, just
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so long as the tags, options, and syntax you use are legal. Once you have
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edited the file manually then save it back out in text format again. The best
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use of editing the configuration file manually is probably for adding your own
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customised packages to the installation.
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<P>
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<P>
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<H3>Boot the Machine</H3>
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<P>The most common method of booting a client ready for installation over a network
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is to use a floppy disk.
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<OL>
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<LI>If you have not already created a boot floppy then do it now (you only
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need to do this step once, when you have a boot floppy you can install as many
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machines as you like with a single floppy):
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<UL>
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<LI>Locate the floppy image that you need to use.</LI>
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<LI>Copy the image to your floppy disk (make sure you have one
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inserted in the drive, but not mounted) using the following command:
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<PRE>
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dd if=your-file.img of=/dev/fd0
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</PRE>
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</LI>
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</UL>
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</LI>
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<LI>If you are doing an automated install (with the config file) then you
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should follow this step (otherwise skip to next step):
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<UL>
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<LI>Copy your config file to the root directory of the floppy</LI>
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</UL>
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</LI>
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<LI>Insert your floppy disk into the client machine that you want to install.
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Make sure that the floppy disk is in the boot list of your BIOS and turn on your
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machine to boot from the floppy.</LI>
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<LI>At the boot prompt:
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<UL>
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<LI>If you are doing an automated install then start the automated
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process</LI>
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<LI>If you're not using config files then press ENTER for the
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default installation</LI>
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</UL>
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</LI>
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<LI>Finish the installation.</LI>
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</OL>
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<P>Don't forget that some distributions will allow you to boot from other media as
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well as floppy images to perform network installations. Also, each distribution
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normally has a set of extra boot options that you can use if the above method
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does not work on your hardware. These extra configuration options are normally
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for less common hardware but are provided to make sure you can perform network
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installs.
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<P>
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<P>
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<P>
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<P>
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<HR>
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