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Chapter 14. Installing kdump
The kdump service is installed and activated by default on the new versions of RHEL 8 installations.
14.1. What is kdump
kdump provides a crash dumping mechanism that generates a vmcore file containing system memory contents for analysis. It uses kexec to boot into a reserved second kernel without a reboot. The crashed kernel’s memory is captured accurately, as a result.
A kernel crash dump can be the only information available if a system failure occur. Therefore, operational kdump is important in mission-critical environments. Red Hat advises to regularly update and test kexec-tools in your normal kernel update cycle. This is important when you install new kernel features.
If you have multiple kernels on a machine, you can enable kdump for all installed kernels or for specified kernels only. When you install kdump, the system creates a default /etc/kdump.conf file. /etc/kdump.conf includes the default minimum kdump configuration, which you can edit to customize the kdump configuration.
14.2. Installing kdump using Anaconda
The Anaconda installer provides a graphical interface screen for kdump configuration during an interactive installation. You can enable kdump and reserve the required amount of memory.
Procedure
On the Anaconda installer, click KDUMP and enable
kdump:- In Kdump Memory Reservation, select Manual` if you must customize the memory reserve.
In KDUMP > Memory To Be Reserved (MB), set the required memory reserve for
kdump.
14.3. Installing kdump on the command line
Installation options such as custom Kickstart installations, in some cases does not install or enable kdump by default. The following procedure helps you enable kdump in this case.
Prerequisites
- An active RHEL subscription.
-
A repository containing the
kexec-toolspackage for your system CPU architecture. -
Fulfilled requirements for
kdumpconfigurations and targets. For details, see Supported kdump configurations and targets.
Procedure
Check if
kdumpis installed on your system:rpm -q kexec-tools
# rpm -q kexec-toolsCopy to Clipboard Copied! Toggle word wrap Toggle overflow Output if the package is installed:
kexec-tools-2.0.17-11.el8.x86_64
kexec-tools-2.0.17-11.el8.x86_64Copy to Clipboard Copied! Toggle word wrap Toggle overflow Output if the package is not installed:
package kexec-tools is not installed
package kexec-tools is not installedCopy to Clipboard Copied! Toggle word wrap Toggle overflow Install
kdumpand other necessary packages:dnf install kexec-tools
# dnf install kexec-toolsCopy to Clipboard Copied! Toggle word wrap Toggle overflow
From kernel-3.10.0-693.el7 onwards, the Intel IOMMU driver is supported for kdump. For kernel-3.10.0-514[.XYZ].el7 and early versions, you must ensure that Intel IOMMU is disabled to prevent an unresponsive capture kernel.
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