What is kdump?

blackrhino

Also see:
https://en.wikipedia.org/wiki/Kdump_(Linux)
kexec(8) - directly boot into a new kernel

kdump is used to obtain kernel crash dump (vmcore). kdump via kexec; boots linux into a capture kernel in the event of a crash, a memory dump is saved (vmcore) for debugging.

Redhat Note:

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.