Exploring the Debian Installer

LXer Feature: 09-Mar-2007 Don Parris looks at the Debian Installer, providing something of an overview of the installation process, revealing one or two potential pain points and what the Debian Installer team is doing to improve it.

Contemplating a Debian Installation

Debian GNU/Linux used to have a reputation as the toughest GNU/Linux distribution to install, yet the easiest to maintain. In fact, Debian's package management system has played a huge role in the proliferation of projects based on Debian. Suffice it to say that anyone who can install their own operating system can generally install Debian Etch with little or no trouble. If you've never installed Debian before, it's fairly easy to walk through the default installation without realizing you have options.

Let's explore the Debian Installer, to find out just what options we do have. Our first stop should be at the Debian Installation Guide. Choose the appropriate version and keep it handy (if possible). When you first boot the Install system, you'll see a prompt (in the case of an x86 NetInstall CD, anyway) right below the Debian logo. Use the F1 key to get a list of optional boot parameters you can enter to modify the installation process.

Know Your Options

Debian's installer is actually a single program with three different front-ends (Text, Newt, and GTK), each of which is functionally identical, for the most part. With the exception of creating encrypted partitions - a feature currently only available through the Newt front-end (see References below) - each of the front-ends works the same way. Which front-end you prefer is a matter of your computer hardware and/or your own personal preferences. The various options are covered in Chapter 5, Section 2 of the Debian Installation Guide.

The text front-end is best for serial consoles, while the Newt front-end is the default for now, and the GTK front-end should work for most modern hardware. You can change the theme for the Newt and GTK front-ends if you're visually impaired by setting the theme: debian-installer theme=dark. This is also the opportunity to set the location of any preseed files/URLs or to disable the DHCP probe, USB probe and other potential trouble points. You can even let the installer know you're using a left-handed mouse configuration.

KDE fans should know that you can install KDE instead of GNOME by adding the boot parameter: tasks="standard, kde-desktop". If you want both, you can add desktop to that line. This sure beats the workaround howtos I've seen and used. According to Frans Pop, of the Debian Installer team, this will install KDE instead of Debian's default graphical desktop, GNOME. As of Debian Etch, users will be able to obtain images that offer a given graphical environment by default. The Installation Guide reveals several other options that might interest you, so check it out.

How Much Control Do You Want Today?

The default installation mode is the "standard" mode (referred to as "high priority"), which means that much of the installation process is automated. A user could actually go through the entire installation and never realize there is a full-fledged menu-driven installer operating behind the scenes. In other words, you can get a whole lot of control over the installation, if you like. All you have to do is change the mode or priority at the boot prompt.

The higher the priority, the less control you have over the installation process. Hence, a non-technical user could essentially install Debian Etch if they can answer questions about their language, country and keyboard layout, set the root password and follow the steps to create the first regular user. Well, there's a bit more to it than that, but you get the idea. The user will only see the installer menu if any errors occur.

Changing the priority at the boot prompt to "medium" will enable you to step through the components of the installer menu in turn. If you know you'll need to pass options to kernel modules as they are installed, then you'll want "Expert" mode, or "Low Priority". After having completed installations using the Expert and Standard modes, rest assured that the only reasons to use the Expert mode are:

• you really need those kernel module options (or certain other options)
• you're writing a research paper
• you're a serious control freak
• you're a glutton for punishment

You can also automate the installation, using "preseeding" (or pre-answering the questions). Additionally, if you have messed up your already-installed system, you can run in rescue mode to try and restore it. Incidentally, you can also start an installation using the target computer, and then use the SSH option to finish the installation from a remote computer. The installer lets you set a password to use when connecting from the remote computer later.

Stepping Through the Standard Installation

The Debian Installer takes you through what I consider to be four phases of questions. Phase I involves information about your language settings, as well as your host and domain name. Phase II is the hard disk partitioning phase. Phase III covers the time zone, root password and first user. Phase IV covers which software needs to be installed and from where.

You will need to know the following:

• Phase I
  • Your language
  • What country you're in
  • Which keyboard layout you need (i.e., American or British English)
  • The name of the computer (host name)
  • Your domain name
• Phase II
  • Whether to use Guided or manual partitioning, and whether to use the whole disk
  • Which disk to use
  • Which pre-configured partitioning scheme you want
  • Acknowledge the partition scheme
  • Confirm to write the changes to disk
• Phase III
  • What time zone you're in
  • the root user's password (since you're installing the system, just make up one)
  • What the regular user's name, userid, and password are (since this is likely yourself, you hopefully know all of this)
• Phase IV
  • whether to use a mirror (you really should choose the closest one to you)
  • whether you want to participate in the survey that polls your software to see what you're actually using.
  • which tasks (groups of packages) to install

At High Priority (standard mode), this process takes only as long as you need to type in the answers, with a short break in between each set of questions. However, the partitioning phase can quickly become a time killer if you do not accept the default values for the partition scheme. This is because the Debian Installer will not currently allow users to change all the settings for a given partition in one screen. You must choose the partition, then the setting, edit that one setting, and finally return to the screen for that partition to choose the next setting to edit.

The Debian Installer developers are well aware of the installer's shortcoming. When I suggested a way to setup the paritition configuration screen to allow the user to set the settings while viewing that screen, Frans Pop replied that it's not so simple. According to him, the debconf protocol limits what they can do. In fact, the directfb technology was only accepted into GTK a little over a year ago. There is an apparently stalled project to port gparted to the C programming language, which could then be used for partitioning, presumably in place of partman (at least as an option).

Wrapping Up The Installation Process

Once you have answered the questions and selected which tasks to install, the installer finishes grabbing the software from the installation source (CD, Internet, or local repository). By default, the installer ejects the CD once it has completed the installation, and waits for you to reboot the computer. You can change that default if, for example, you are using a USB key for the installation process, and don't need to worry about ejecting the CD. Once you reboot, you should see your shiny new Debian GNU/Linux system.

I have installed various versions of GNU/Linux since 1997. Yast is a great installation tool. Ubuntu and PCLinuxOS have comparable installation processes (different, but still fairly similar). The Debian installer is not, in my view, quite as easy as the current Ubuntu installer. Still, it is a fantastic, simple installer that is adaptable to a wide range of installation scenarios. If you have about an hour and can read, you really should consider giving Debian Etch a whirl.

References

partman-crypto's limited availability only affects the normal partitions, not the "Guided Encrypted LVM" option.

Thanks to Frans Pop for his willingness to answer my questions about the installer