I'm using standard df plugin, and one of the filesystems is named "root".
This makes munin_get_keypath fail and thus, munin-graph can't find a proper file:
2010/03/06 16:34:09 [DEBUG] RRD name / filename: root / /usr/local/var/munin/--g.rrd
Though it is strange, that munin-update doesn't complain:
2010/03/06 16:48:20 [DEBUG] Made rrd filename: /usr/local/var/munin/kadlubek/kadlubek-df-root_usr-g.rrd.
I guess that's because munin update uses following way of composing filename:
my $file = sprintf("%s-%s-%s-%s.rrd",
$path,
$service,
$ds_name,
$type_id);
And munin-graph the following one:
$filename = munin_get_rrd_filename($field, $path);
And munin_get_rrd_filename calls munin_get_filename, which calls munin_get_keypath, which has a line (923 in Utils.pm - http://munin.projects.linpro.no/browser/trunk/master/lib/Munin/Master/Utils.pm?rev=3236#L923):
last if $name eq 'root';
Commenting this line is not a solution, as it will break other filename creation.
As a workaround I have set filepath on this field in munin.conf:
df.root.filename /usr/local/var/munin/kadlubek/kadlubek-df-root-g.rrd
