RCHE Red Hat Certified Engineer Linux Study Guide[c] Exam (Rh302)

The following are some of the key points from the certification objectives in Chapter 3.

Installation Troubleshooting

• When you start in graphical mode, you're taken to the seventh virtual console, which you can access with the CTRL-ALT-F7 command. A bash shell is on the second virtual console, an installation message log is on the third, kernel messages are on the fourth, and the output of format commands on each filesystem is displayed. If you want to see other screens, press the following key sequences at any time:

• CTRL-ALT-F1 Installation display; if you're running the installation process in text mode, this is the main display.

• CTRL-ALT-F2 The bash shell gives you access to limited system information.

• CTRL-ALT-F3 The Installation message log is displayed.

• CTRL-ALT-F4 Displays all kernel messages.

• CTRL-ALT-F5 The installation displays partition formatting.

Postinstallation Validation

• The file /var/log/dmesg contains boot messages duplicated from the console output, as seen each time you boot Linux.

• The /root/install.log file contains a list of the installed packages.

• The installation program reboots your computer when it's done. If you configured a graphical login, Linux starts in runlevel 5. Alternatively, if you configured a text login, Linux starts in runlevel 3.

Boot Loaders: GRUB and LILO

• The original Intel motherboard design provided a mechanism to start most any operating system. It would load a boot program from the Master Boot Record of the first available disk.

• The new default Red Hat boot loader is GRUB, the GRand Unified Boot Loader.

• You can edit GRUB directly during the boot process or pass commands to the kernel. For example, at the GRUB screen, if you add the word single to the end of the kernel argument, Linux starts in single-user mode.

• Single-user mode is the most commonly used option. This is the system maintenance mode for experienced Linux administrators.

Partitioning Utilities

• The fdisk utility is universally available and should be one of the first tools you learn as a Linux administrator.

• Disk Druid is the alternative to fdisk that is available only during the Red Hat installation process.

RAID Configuration and Data Recovery

• Software-based RAID can be set up on any number of physical partitions. Hardware-based RAID requires separate physical drives for each partition.

• You can set up software-based RAID through the Red Hat Enterprise Linux installation program.

• RAID has several different levels. Only three are currently supported by Red Hat Linux: levels 0, 1, and 5. Only RAID levels 1 and 5 offer true data protection against the failure of a single hard drive.

• RAID 0 and 1 require two or more drives, while RAID 5 requires three or more drives.

Logical Volume Management: Configuration and Administration

• Logical Volume Management allows you to manage the effective size of your active partitions.

• Once properly configured through fdisk, you can collect LVM chunks known as Logical Extents into Logical Volumes.

• Once Logical Volumes are collected into a Volume Group, it functions as a partition that you can resize as needed.

Automated Installation with Kickstart

• Kickstart is Red Hat's solution for an automated simultaneous installation of Red Hat Enterprise Linux on several computers.

• Kickstart installations can be configured to take installation files from a CD-ROM or an NFS, FTP, or HTTP server.

• There are two ways to create a Kickstart file: from the configuration from when you installed Linux as documented in the /root/anaconda-ks.cfg file, or from what you can configure with the GUI Kickstart Configurator.