Hi Michael,
the warning message means that Kdump integration is enabled for the host, but the host doesn't contain proper kdump configuration. This can happen due to following reasons:
1. Kdump integration was enabled, but host was not reinstalled after that
- every time you enable/disable kdump integration for the host you need to reinstall the host by moving the host to Maintenance and executing Reinstall
2. There was some error during kdump integration configuration during host installation
- details about the error can be found in proper host installation log (it's displayed in Events tab), all existing logs can be found on engine machine in /var/log/ovirt-engine/host-deploy directory
More details about Kdump integration can be found at [1] or [2].
Thanks
Martin Perina