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 <sect1 id="install-overview">
 <title>Overview of the Installation Process</title>
<para>

First, just a note about re-installations. With &debian;, a
circumstance that will require a complete re-installation of your
system is very rare; perhaps mechanical failure of the hard disk would
be the most common case.

</para><para>

Many common operating systems may require a complete installation to
be performed when critical failures take place or for upgrades to new
OS versions. Even if a completely new installation isn't required,
often the programs you use must be re-installed to operate properly in
the new OS.

</para><para>

Under &debian-gnu;, it is much more likely that your OS can be repaired
rather than replaced if things go wrong. Upgrades never require a
wholesale installation; you can always upgrade in-place. And the
programs are almost always compatible with successive OS releases.  If
a new program version requires newer supporting software, the &debian;
packaging system ensures that all the necessary software is
automatically identified and installed. The point is, much effort has
been put into avoiding the need for re-installation, so think of it as
your very last option. The installer is <emphasis>not</emphasis>
designed to re-install over an existing system.

</para><para>

Here's a road map for the steps you will take during the installation
process.

</para>

<orderedlist>
<listitem><para>

Back up any existing data or documents on the hard disk where you
plan to install.

</para></listitem>
<listitem><para>

Gather information about your computer and any needed documentation,
before starting the installation.

</para></listitem>
<listitem arch="not-x86"><para>

Create partitionable space for &debian; on your hard disk.

</para></listitem>
<listitem><para>

Locate and/or download the installer software and any specialized
driver or firmware files your machine requires.

</para></listitem>
<listitem><para>

Set up boot media such as CDs/DVDs/USB sticks or provide a network boot
infrastructure from which the installer can be booted.

</para></listitem>
<listitem><para>

Boot the installation system.

</para></listitem>
<listitem arch="not-s390"><para>

Select the installation language.

</para></listitem>
<listitem arch="not-s390"><para>

Activate the ethernet network connection, if available.

</para></listitem>

<listitem arch="s390"><para>

Configure one network interface.

</para></listitem>
<listitem arch="s390"><para>

Open an ssh connection to the new system.

</para></listitem>
<listitem arch="s390"><para>

Attach one or more DASDs (Direct Access Storage Device).

</para></listitem>

<listitem arch="x86"><para>
If necessary, resize existing partitions on your target harddisk to make
space for the installation.
</para></listitem>

<listitem><para>

Create and mount the partitions on which &debian; will be installed.

</para></listitem>
<listitem><para>

Watch the automatic download/install/setup of the
<firstterm>base system</firstterm>.

</para></listitem>
<listitem><para>

Select and install <firstterm>additional software</firstterm>.

</para></listitem>
<listitem><para>

Install a <firstterm>boot loader</firstterm>
which can start up &debian-gnu; and/or your existing system.

</para></listitem>
<listitem><para>

Load the newly installed system for the first time.

</para></listitem>
</orderedlist>

<para condition="gtk">

For &arch-title; you have the option of using
<phrase arch="any-x86">a</phrase>
<phrase arch="arm64">an experimental</phrase>
<phrase arch="powerpc">an experimental</phrase>
graphical version of the installation system. For more information about
this graphical installer, see <xref linkend="graphical"/>.

</para><para>

If you have problems during the installation, it helps to know which
packages are involved in which steps. Introducing the leading software
actors in this installation drama:

</para><para>

The installer software, <classname>debian-installer</classname>, is
the primary concern of this manual. It detects hardware and loads
appropriate drivers, uses <classname>dhcp-client</classname> to set up the
network connection, runs <classname>debootstrap</classname> to install
the base system packages, and runs <classname>tasksel</classname> to allow
you to install certain additional software.
Many more actors play smaller parts in this process,
but <classname>debian-installer</classname> has completed its task when
you load the new system for the first time.

</para><para>

To tune the system to your needs, <classname>tasksel</classname> allows you
to choose to install various predefined bundles of software like a Web
server or a Desktop environment.

</para><para>

One important option during the installation is whether or not to install
a graphical desktop environment, consisting of the X Window System and
one of the available graphical desktop environments.
If you choose not to select the <quote>Desktop environment</quote> task,
you will only have a relatively basic, command line driven system.
Installing the Desktop environment task is optional because in relation to a
text-mode-only system it requires a comparatively large amount of disk space
and because many &debian-gnu; systems are
servers which don't really have any need for a graphical user interface
to do their job.

</para><para arch="not-s390">

Just be aware that the X Window System is completely separate from
<classname>debian-installer</classname>, and in fact is much more
complicated. Troubleshooting of the X Window
System is not within the scope of this manual.

</para>
 </sect1>
