The reason for this is that rrdtool changed its behavior between 1.4
and 1.5. It used to include timestamps in the xport command, and now
it does not by default. You can add --showtime to rrdtool xport to
restore the previous behavior. In ganglia, this ends up being in
/usr/share/ganglia-webfrontend/graph.php on line 1089:
--------------
// This command will export values for the specified format in XML
$command = $rrdtool .
" xport --start '" . $rrdtool_graph_start .
"' --end '" . $rrdtool_graph_end . "' --showtime"
--------
Modifying it as above fixes the bug. I think this should be patched in
debian 9 as it is low impact and only fixes a bug.
See: https://sourceforge.net/p/ganglia/mailman/message/35440616/
and: https://github.com/oetiker/rrdtool-1.x/issues/672
--
-Alex
