MikeMcGrath/MedialessInstall

This is a Draft. It might kill your cat or offend your mother!

Introduction

This document describes a method of install that can be done without using local media such as a CD or DVD. Those with experience in PXE booting will find much of this document familiar.

Normal Installation

Typical installations rely on a CD or DVD and use the local media as an install source.

1. Insert boot media 1. Boot machine 1. CD Boot 1. Anaconda runs 1. Install complete 1. Reboot

{{{1}}}

Medialess Installation

Unlike a normal CD or DVD install a medialess installation does not require a CD/DVD or USB key. It does, however, require a current working system and a writeable drive. To understand how the medialess installion works one needs to understand what happens during a normal boot process.

1. power on 1. BIOS check / POST 1. Boot Loader (grub) 1. Kernel loads 1. Init is called and system is loaded.

In our case we just want grub to load a different kernel and have that kernel load the Anaconda install.

This method does have certain risks associated with it. During a normal install if something happens during the install, say a power outage or even a network outage the install may fail and have to be restarted by rebooting, and boot off of the CD again. If medialess install fails after anaconda has formatted the boot drive, that box cannot be rebooted into the install. If this happens just do a normal install

Checklist

Before a medialess install can be performed there is a checklist that must be met.

1. Network access 1. Local or remote install source (like http://download.fedora.redhat.com/pub/fedora/linux/core/development/i386/os/) 1. Access to the current system (remote or physical)

For the install source it is *HIGHLY* recommended to have a local reliable mirror to use as your install medium. If the chosen mirror is too overloaded it is quite possible an install will fail leaving the target box un-bootable.

Preparations

Preparing a box is fairly easy, we need to download the installation kernel and initrd file and configure grub to boot off of them.

Download Kernel and Initrd

Preferrably from your local mirror download using the following commands.

cd /boot
wget -O vmlinuz-install 'http://download.fedora.redhat.com/pub/fedora/linux/core/development/i386/os/images/pxeboot/vmlinuz'
wget -O initrd-install 'http://download.fedora.redhat.com/pub/fedora/linux/core/development/i386/os/images/pxeboot/initrd.img'

Edit Grub Config

Tell grub to boot off of the new kernel. You will need to alter this to match the format of your grub config (/boot/grub/grub.conf). For example, your root line might be different or you may need to provide a full path to your kernel and initrd images. When in doubt, duplicate what's already the file.

#/boot/grub/grub.conf
title Fedora Rawhide Install
root (hd0,0)
kernel /vmlinuz-install method=http://download.fedora.redhat.com/pub/fedora/linux/core/development/i386/os/
initrd /initrd-install

IP and kickstart configuration information can also be appended to the kernel portion here for those wanting a fully automated re-install without a DHCP server

Reboot

All thats left is a reboot. When the new grub screen comes up make sure to select the new Install option and it should boot and re-install completely without the need of a CD or DVD.

Search