15.11. Running kdump on systems with encrypted disk

When you run a LUKS encrypted partition, systems require certain amount of available memory. If the system has less than the required amount of available memory, the cryptsetup utility fails to mount the partition. As a result, capturing the vmcore file to an encrypted target location fails in the second kernel (capture kernel).

The kdumpctl estimate command helps you estimate the amount of memory you need for kdump. kdumpctl estimate prints the crashkernel value, which is the most suitable memory size required for kdump.

The crashkernel value is calculated based on the current kernel size, kernel module, initramfs, and the LUKS encrypted target memory requirement.

If you are using the custom crashkernel= option, kdumpctl estimate prints the LUKS required size value. The value is the memory size required for LUKS encrypted target.