While you've read about many troubleshooting scenarios throughout this book, it's the troubleshooting part of the Red Hat exams that I believe causes the most "fear and loathing" among Red Hat certification candidates.
Troubleshooting is a mindset based on experience and a systematic way of thinking. Troubleshooting strategies on the Red Hat exams are based on the simplest problems that you can check quickly, moving to more complex problems.
Red Hat has done excellent work addressing some problems that formerly led to unbootable systems. For example, flaws in the /etc/fstab file used to lead to an unbootable system. Now most users would hardly know the difference if this file is missing.
The most important troubleshooting tool is the linux rescue environment, which can bypass boot problems, from a missing GRUB boot loader to a missing kernel. In most cases, the first installation CD, booted into the linux rescue environment, can detect and mount even damaged installations of RHEL.
This chapter focuses on the Troubleshooting and System Maintenance section of the RHCT and RHCE exams, as defined in the Inside the Exam sidebar. It further focuses on troubleshooting skills, as they evoke more concern than regular system maintenance.
This chapter includes a number of exercises for which you'll need the help of a partner. When you start an exercise, let your partner have your computer and wait until your system begins to reboot. This chapter includes enough exercises to allow you and your partner to take turns working with the system.