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
is a service that provides a crash dumping mechanism and generates a crash dump or a vmcore
dump file. vmcore
includes the contents of the system memory for analysis and troubleshooting. kdump
uses the kexec
system call to boot into the second kernel, capture kernel, without a reboot. This kernel captures the contents of the crashed kernel’s memory and saves it into a file. The second kernel is available in a reserved part of the system memory.
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-tools
package for your system CPU architecture. -
Fulfilled requirements for
kdump
configurations and targets. For details, see Supported kdump configurations and targets.
Procedure
Check if
kdump
is installed on your system:# rpm -q kexec-tools
Output if the package is installed:
kexec-tools-2.0.17-11.el8.x86_64
Output if the package is not installed:
package kexec-tools is not installed
Install
kdump
and other necessary packages:# dnf install kexec-tools
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.