Chapter 10. Installing kdump
In many cases, the
kdump service is installed and activated by default on the new Red Hat Enterprise Linux installations. The following sections brings information about
kdump and how to install
kdump when it is not enabled by default in some cases.
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.
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
The Anaconda installer provides a screen for
kdump configuration when performing an interactive installation using the graphical or text interface. The installer screen is titled
Kdump and is available from the main
Installation Summary screen, and only allows limited configuration - you can only select whether
kdump is enabled and how much memory is reserved.
Some installation options, such as custom Kickstart installations, in some cases do not install or enable
kdump by default. If this is the case on your system, follow the procedure below to install
- An active Red Hat Enterprise Linux subscription
- A repository containing the kexec-tools package for your system CPU architecture
Fulfilled requirements for
kdumpconfigurations and targets
Execute the following command to check whether
kdumpis installed on your system:
$ rpm -q kexec-tools
Output if the package is installed:
Output if the package is not installed:
package kexec-tools is not installed
kdumpand other necessary packages by:
# yum install kexec-tools
Starting with Red Hat Enterprise Linux 7.4 (kernel-3.10.0-693.el7) the
Intel IOMMU driver is supported with
kdump. For prior versions, Red Hat Enterprise Linux 7.3 (kernel-3.10.0-514[.XYZ].el7) and earlier, it is advised that
Intel IOMMU support is disabled, otherwise kdump kernel is likely to become unresponsive.