it would be nice to have a feature to ignore hosts that are down, at the moment
(atleast hosts that need to be walked) give out a warning and appear as void in
the graphs. and as the graph is drawn from the void data it appears that the
host had for example the same load while it was down. which is not true.

This might be good for hosts that aren't in the same network, but it's not a
good thing for hosts that tend to be down now and then.

the right way to deal with this would be to dump 0 as the value when a host is
down.