Two-Minute Drill


Here are some of the key points from the certification objectives in Chapter 8.

The Basics of the Kernel

  

The kernel lies at the heart of the operating system.

  

Modular kernels, with separate device modules, are more efficient than monolithic kernels, where device drivers are integrated into the kernel.

  

If you're going to update your kernel, you should keep a copy of your current working kernel.

  

Linux kernels and related files are stored in the /boot directory.

  

The /proc directory provides a window to what Linux sees in your computer.

  

The lsmod command lists currently loaded modules; important related commands are insmod, rmmod, and modprobe.

  

Basic RHEL modules can be loaded from the kernel-devel RPM.

New Kernels, the Easy Way

  

Kernel version numbers are organized in major.minor.patch format. Red Hat adds a build number to the Linux kernels that it builds from source code.

  

It's fairly easy to install a Red Hat kernel from RPM, as long as you remember to install and not upgrade. This allows you to return to the current working kernel if you have a problem.

  

Sometimes all you need is a kernel patch, which supports upgrades of one patch version number. Unfortunately, patches are not always the best option for Red Hat built kernels.

  

When you install a Red Hat kernel from RPM, the process should automatically update your GRUB boot loader.

Kernel Sources

  

Kernel sources can be loaded from the kernel source RPM or from a Linux kernel tarball downloaded from a site such as ftp.kernel.org.

  

Installing the Red Hat kernel source RPM requires the rpmbuild command.

  

Once installed, the kernel source tree is available through /usr/src/redhat/BUILD directory.

Recompiling a Kernel

  

To optimize the Linux kernel, it is a best practice to compile kernels with only needed elements and configure modules for most hardware.

  

Your current kernel configuration is stored in the config-`uname -r` file in the /boot directory.

  

You can modify kernel settings from the kernel source code directory with tools that you can open with one of the following commands: make config, make menuconfig, make xconfig, or make gconfig.

  

Once you've made the proper backups and boot disks and set the EXTRAVERSION variable in your Makefile, you're ready to customize your kernel.

  

Once you've settled on and saved your changes, run the make rpm command. It should compile your new kernel and create an RPM in the /usr/src/redhat/RPMS directory, which you can use to install your custom kernel.

Advanced Partitioning: Software RAID

  

Red Hat supports several levels of software RAID, including RAID 0, RAID 1, RAID 5, and RAID 6.

  

To make software RAID work, you need to designate the partition specifically as such in fdisk or parted.

  

RAID arrays as configured are shown in /proc/mdstat.

  

RAID arrays can be created and modified with the mdadm command.

Advanced Partitioning: Logical Volume Management

  

LVM is based on physical volumes, logical volumes, and volume groups.

  

You can create and add LVM systems with a wide variety of commands starting with pv*, lv*, and vg*.

  

The GUI LVM tool is an alternative for those who don't remember all of the commands required to manage logical volumes.



RHCE Red Hat Certified Engineer Linux Study Guide (Exam RH302)
Linux Patch Management: Keeping Linux Systems Up To Date
ISBN: 0132366754
EAN: 2147483647
Year: 2004
Pages: 227
Authors: Michael Jang

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