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Chapter 10. Installing kdump

In many cases, the kdump service is installed and activated by default on the new Red Hat Enterprise Linux installations. This section includes information about kdump.

10.1. What is kdump

kdump is a service providing a crash dumping mechanism. The service enables you to save the contents of the system’s memory for later analysis. kdump uses the kexec system call to boot into the second kernel (a capture kernel) without rebooting; and then captures the contents of the crashed kernel’s memory (a crash dump or a vmcore) and saves it. The second kernel resides in a reserved part of the system memory.

Important

A kernel crash dump can be the only information available in the event of a system failure (a critical bug). Therefore, ensuring that kdump is operational is important in mission-critical environments. Red Hat advise that system administrators regularly update and test kexec-tools in your normal kernel update cycle. This is especially important when new kernel features are implemented.

10.2. Performing kdump installation

In many cases, the kdump service is installed and activated by default on new Red Hat Enterprise Linux installations. This procedure provides information on how to install kdump when it is not enabled by default in some cases.

The Anaconda installer includes a screen for kdump configuration when performing an interactive installation using the graphical or text interface. The installer screen is titled as KDUMP and is available from the main Installation Summary screen and only allows limited configuration. You can only enable KDUMP and reserve the required amount of memory.

Enable kdump during RHEL installation

Some installation options, for example custom Kickstart installations, do not support installing or enabling kdump by default. In such scenarios, you can install kdump using the procedure described in this section.

Prerequisites

  • An active RHEL subscription
  • A repository containing the kexec-tools package for your system CPU architecture
  • Fulfilled requirements for kdump configurations and targets

Procedure

  1. Check the status of kdump installation on your system:

    # rpm -q kexec-tools

    Output if the package is installed:

    # kexec-tools-2.0.22-13.el9.x86_64

    Output if the package is not installed:

    # package kexec-tools is not installed
  2. Install kdump and other necessary packages:

    # yum install kexec-tools