As per https://github.com/prometheus/node_exporter/pull/1429#discussion_r304210103
we want to fetch all devices and all fs types.
Currently, this is done by setting empty string which breaks most queries which rely on it.
This fixes it by setting the appropriate selector instead of empty string.
Signed-off-by: Sergiusz Urbaniak <sergiusz.urbaniak@gmail.com>
This addresses the blissful scenario where single-node failures are
unproblematic. No reason to wake somebody up if a node is about to
screw itself up by filling the disk.
Signed-off-by: beorn7 <beorn@grafana.com>
