Testing Kdump functionality in CentOS/RHEL 9 – The Ranjan.info


Kernel crashes are inevitable events in any operating system environment. When these accidents occur, it is essential to have mechanisms in place to collect critical diagnostic information for analysis and troubleshooting. In Red Hat Enterprise Linux (RHEL) 9, the Kdump utility serves as a powerful tool for capturing kernel crash data, aiding in the resolution of system failures.

Before relying on Kdump in a critical environment, it is necessary to verify that the service is enabled and functional. This can be done by executing the following command:

$ systemctl is-active kdump

A response of “Active” indicates that the Kdump service is up and running, ready to capture crash dumps when needed.

Once confirmed that Kdump is active, the next step is to perform a test to ensure that it can effectively capture kernel crash data. The steps to conduct a Kdump test are given below:

1. Enable SysRq: Kdump relies on the SysRq mechanism to trigger a kernel crash. Enable SysRq by executing the following command:

$ echo 1 > /proc/sys/kernel/sysrq

2. Trigger Kernel Crash: With SysRq enabled, use the following command to intentionally crash the kernel and initiate the Kdump process:

$ echo c > /proc/sysrq-trigger

Comment: Executing this command will crash the system, requiring a reboot.

Upon triggering a kernel crash, Kdump will begin action, capturing a vmcore file containing the necessary diagnostic information. The location where the vmcore file is saved can be specified in the Kdump configuration.

It is important to emphasize that this testing should only be performed in a controlled environment, as intentionally crashing the kernel will result in system downtime and require a reboot to resume normal operation.

In conclusion, testing Kdump functionality in RHEL 9 is an important step towards ensuring system reliability and resiliency. By following the steps outlined, administrators can verify that Kdump is properly configured and ready to capture kernel crash data when needed, thus facilitating efficient troubleshooting and resolution of system issues.

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By Ranjan