Kdump is the Linux kernel crash-dump mechanism. Oracle recommends that you enable the Kdump feature. In the event of a system crash, Kdump creates a memory image (vmcore) that can help in determining the cause of the crash. Enabling Kdump requires you to reserve a portion of system memory for exclusive use by Kdump. This memory is unavailable for other uses.

Kdump uses kexec to boot into a second kernel whenever the system crashes. kexec is a fast-boot mechanism which allows a Linux kernel to boot from inside the context of a kernel that is already running without passing through the bootloader stage.